add utils.path.ensure_dir_exists

Ensures that a directory exists,
and protects against a common race condition when multiple
processes try to create the same directory.

IPython/core/application.py

@@ -1,392 +1,390 b''
 # encoding: utf-8
 """
 An application for IPython.
 
 All top-level applications should use the classes in this module for
 handling configuration and creating configurables.
 
 The job of an :class:`Application` is to create the master configuration
 object and then create the configurable objects, passing the config to them.
 
 Authors:
 
 * Brian Granger
 * Fernando Perez
 * Min RK
 
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import atexit
 import errno
 import glob
 import logging
 import os
 import shutil
 import sys
 
 from IPython.config.application import Application, catch_config_error
 from IPython.config.loader import ConfigFileNotFound
 from IPython.core import release, crashhandler
 from IPython.core.profiledir import ProfileDir, ProfileDirError
-from IPython.utils.path import get_ipython_dir, get_ipython_package_dir
+from IPython.utils.path import get_ipython_dir, get_ipython_package_dir, ensure_dir_exists
 from IPython.utils import py3compat
 from IPython.utils.traitlets import List, Unicode, Type, Bool, Dict, Set, Instance
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
 
 #-----------------------------------------------------------------------------
 # Base Application Class
 #-----------------------------------------------------------------------------
 
 # aliases and flags
 
 base_aliases = {
     'profile-dir' : 'ProfileDir.location',
     'profile' : 'BaseIPythonApplication.profile',
     'ipython-dir' : 'BaseIPythonApplication.ipython_dir',
     'log-level' : 'Application.log_level',
     'config' : 'BaseIPythonApplication.extra_config_file',
 }
 
 base_flags = dict(
     debug = ({'Application' : {'log_level' : logging.DEBUG}},
             "set log level to logging.DEBUG (maximize logging output)"),
     quiet = ({'Application' : {'log_level' : logging.CRITICAL}},
             "set log level to logging.CRITICAL (minimize logging output)"),
     init = ({'BaseIPythonApplication' : {
                     'copy_config_files' : True,
                     'auto_create' : True}
             }, """Initialize profile with default config files.  This is equivalent
             to running `ipython profile create <profile>` prior to startup.
             """)
 )
 
 
 class BaseIPythonApplication(Application):
 
     name = Unicode(u'ipython')
     description = Unicode(u'IPython: an enhanced interactive Python shell.')
     version = Unicode(release.version)
 
     aliases = Dict(base_aliases)
     flags = Dict(base_flags)
     classes = List([ProfileDir])
 
     # Track whether the config_file has changed,
     # because some logic happens only if we aren't using the default.
     config_file_specified = Set()
 
     config_file_name = Unicode()
     def _config_file_name_default(self):
         return self.name.replace('-','_') + u'_config.py'
     def _config_file_name_changed(self, name, old, new):
         if new != old:
             self.config_file_specified.add(new)
 
     # The directory that contains IPython's builtin profiles.
     builtin_profile_dir = Unicode(
         os.path.join(get_ipython_package_dir(), u'config', u'profile', u'default')
     )
 
     config_file_paths = List(Unicode)
     def _config_file_paths_default(self):
         return [py3compat.getcwd()]
 
     extra_config_file = Unicode(config=True,
     help="""Path to an extra config file to load.
     
     If specified, load this config file in addition to any other IPython config.
     """)
     def _extra_config_file_changed(self, name, old, new):
         try:
             self.config_files.remove(old)
         except ValueError:
             pass
         self.config_file_specified.add(new)
         self.config_files.append(new)
 
     profile = Unicode(u'default', config=True,
         help="""The IPython profile to use."""
     )
 
     def _profile_changed(self, name, old, new):
         self.builtin_profile_dir = os.path.join(
                 get_ipython_package_dir(), u'config', u'profile', new
         )
 
     ipython_dir = Unicode(config=True,
         help="""
         The name of the IPython directory. This directory is used for logging
         configuration (through profiles), history storage, etc. The default
         is usually $HOME/.ipython. This options can also be specified through
         the environment variable IPYTHONDIR.
         """
     )
     def _ipython_dir_default(self):
         d = get_ipython_dir()
         self._ipython_dir_changed('ipython_dir', d, d)
         return d
     
     _in_init_profile_dir = False
     profile_dir = Instance(ProfileDir)
     def _profile_dir_default(self):
         # avoid recursion
         if self._in_init_profile_dir:
             return
         # profile_dir requested early, force initialization
         self.init_profile_dir()
         return self.profile_dir
 
     overwrite = Bool(False, config=True,
         help="""Whether to overwrite existing config files when copying""")
     auto_create = Bool(False, config=True,
         help="""Whether to create profile dir if it doesn't exist""")
 
     config_files = List(Unicode)
     def _config_files_default(self):
         return [self.config_file_name]
 
     copy_config_files = Bool(False, config=True,
         help="""Whether to install the default config files into the profile dir.
         If a new profile is being created, and IPython contains config files for that
         profile, then they will be staged into the new directory.  Otherwise,
         default config files will be automatically generated.
         """)
     
     verbose_crash = Bool(False, config=True,
         help="""Create a massive crash report when IPython encounters what may be an
         internal error.  The default is to append a short message to the
         usual traceback""")
 
     # The class to use as the crash handler.
     crash_handler_class = Type(crashhandler.CrashHandler)
 
     @catch_config_error
     def __init__(self, **kwargs):
         super(BaseIPythonApplication, self).__init__(**kwargs)
         # ensure current working directory exists
         try:
             directory = py3compat.getcwd()
         except:
             # raise exception
             self.log.error("Current working directory doesn't exist.")
             raise
 
     #-------------------------------------------------------------------------
     # Various stages of Application creation
     #-------------------------------------------------------------------------
 
     def init_crash_handler(self):
         """Create a crash handler, typically setting sys.excepthook to it."""
         self.crash_handler = self.crash_handler_class(self)
         sys.excepthook = self.excepthook
         def unset_crashhandler():
             sys.excepthook = sys.__excepthook__
         atexit.register(unset_crashhandler)
     
     def excepthook(self, etype, evalue, tb):
         """this is sys.excepthook after init_crashhandler
         
         set self.verbose_crash=True to use our full crashhandler, instead of
         a regular traceback with a short message (crash_handler_lite)
         """
         
         if self.verbose_crash:
             return self.crash_handler(etype, evalue, tb)
         else:
             return crashhandler.crash_handler_lite(etype, evalue, tb)
     
     def _ipython_dir_changed(self, name, old, new):
         str_old = py3compat.cast_bytes_py2(os.path.abspath(old),
             sys.getfilesystemencoding()
         )
         if str_old in sys.path:
             sys.path.remove(str_old)
         str_path = py3compat.cast_bytes_py2(os.path.abspath(new),
             sys.getfilesystemencoding()
         )
         sys.path.append(str_path)
-        if not os.path.isdir(new):
-            os.makedirs(new, mode=0o777)
+        ensure_dir_exists(new)
         readme = os.path.join(new, 'README')
         readme_src = os.path.join(get_ipython_package_dir(), u'config', u'profile', 'README')
         if not os.path.exists(readme) and os.path.exists(readme_src):
             shutil.copy(readme_src, readme)
         for d in ('extensions', 'nbextensions'):
             path = os.path.join(new, d)
-            if not os.path.exists(path):
                 try:
-                    os.mkdir(path)
-                except OSError as e:
-                    if e.errno != errno.EEXIST:
+                ensure_dir_exists(path)
+            except OSError:
+                # this will not be EEXIST
                         self.log.error("couldn't create path %s: %s", path, e)
         self.log.debug("IPYTHONDIR set to: %s" % new)
 
     def load_config_file(self, suppress_errors=True):
         """Load the config file.
 
         By default, errors in loading config are handled, and a warning
         printed on screen. For testing, the suppress_errors option is set
         to False, so errors will make tests fail.
         """
         self.log.debug("Searching path %s for config files", self.config_file_paths)
         base_config = 'ipython_config.py'
         self.log.debug("Attempting to load config file: %s" %
                        base_config)
         try:
             Application.load_config_file(
                 self,
                 base_config,
                 path=self.config_file_paths
             )
         except ConfigFileNotFound:
             # ignore errors loading parent
             self.log.debug("Config file %s not found", base_config)
             pass
         
         for config_file_name in self.config_files:
             if not config_file_name or config_file_name == base_config:
                 continue
             self.log.debug("Attempting to load config file: %s" %
                            self.config_file_name)
             try:
                 Application.load_config_file(
                     self,
                     config_file_name,
                     path=self.config_file_paths
                 )
             except ConfigFileNotFound:
                 # Only warn if the default config file was NOT being used.
                 if config_file_name in self.config_file_specified:
                     msg = self.log.warn
                 else:
                     msg = self.log.debug
                 msg("Config file not found, skipping: %s", config_file_name)
             except:
                 # For testing purposes.
                 if not suppress_errors:
                     raise
                 self.log.warn("Error loading config file: %s" %
                               self.config_file_name, exc_info=True)
 
     def init_profile_dir(self):
         """initialize the profile dir"""
         self._in_init_profile_dir = True
         if self.profile_dir is not None:
             # already ran
             return
         if 'ProfileDir.location' not in self.config:
             # location not specified, find by profile name
             try:
                 p = ProfileDir.find_profile_dir_by_name(self.ipython_dir, self.profile, self.config)
             except ProfileDirError:
                 # not found, maybe create it (always create default profile)
                 if self.auto_create or self.profile == 'default':
                     try:
                         p = ProfileDir.create_profile_dir_by_name(self.ipython_dir, self.profile, self.config)
                     except ProfileDirError:
                         self.log.fatal("Could not create profile: %r"%self.profile)
                         self.exit(1)
                     else:
                         self.log.info("Created profile dir: %r"%p.location)
                 else:
                     self.log.fatal("Profile %r not found."%self.profile)
                     self.exit(1)
             else:
                 self.log.info("Using existing profile dir: %r"%p.location)
         else:
             location = self.config.ProfileDir.location
             # location is fully specified
             try:
                 p = ProfileDir.find_profile_dir(location, self.config)
             except ProfileDirError:
                 # not found, maybe create it
                 if self.auto_create:
                     try:
                         p = ProfileDir.create_profile_dir(location, self.config)
                     except ProfileDirError:
                         self.log.fatal("Could not create profile directory: %r"%location)
                         self.exit(1)
                     else:
                         self.log.info("Creating new profile dir: %r"%location)
                 else:
                     self.log.fatal("Profile directory %r not found."%location)
                     self.exit(1)
             else:
                 self.log.info("Using existing profile dir: %r"%location)
             # if profile_dir is specified explicitly, set profile name
             dir_name = os.path.basename(p.location)
             if dir_name.startswith('profile_'):
                 self.profile = dir_name[8:]
 
         self.profile_dir = p
         self.config_file_paths.append(p.location)
         self._in_init_profile_dir = False
 
     def init_config_files(self):
         """[optionally] copy default config files into profile dir."""
         # copy config files
         path = self.builtin_profile_dir
         if self.copy_config_files:
             src = self.profile
 
             cfg = self.config_file_name
             if path and os.path.exists(os.path.join(path, cfg)):
                 self.log.warn("Staging %r from %s into %r [overwrite=%s]"%(
                         cfg, src, self.profile_dir.location, self.overwrite)
                 )
                 self.profile_dir.copy_config_file(cfg, path=path, overwrite=self.overwrite)
             else:
                 self.stage_default_config_file()
         else:
             # Still stage *bundled* config files, but not generated ones
             # This is necessary for `ipython profile=sympy` to load the profile
             # on the first go
             files = glob.glob(os.path.join(path, '*.py'))
             for fullpath in files:
                 cfg = os.path.basename(fullpath)
                 if self.profile_dir.copy_config_file(cfg, path=path, overwrite=False):
                     # file was copied
                     self.log.warn("Staging bundled %s from %s into %r"%(
                             cfg, self.profile, self.profile_dir.location)
                     )
 
 
     def stage_default_config_file(self):
         """auto generate default config file, and stage it into the profile."""
         s = self.generate_config_file()
         fname = os.path.join(self.profile_dir.location, self.config_file_name)
         if self.overwrite or not os.path.exists(fname):
             self.log.warn("Generating default config file: %r"%(fname))
             with open(fname, 'w') as f:
                 f.write(s)
 
     @catch_config_error
     def initialize(self, argv=None):
         # don't hook up crash handler before parsing command-line
         self.parse_command_line(argv)
         self.init_crash_handler()
         if self.subapp is not None:
             # stop here if subapp is taking over
             return
         cl_config = self.config
         self.init_profile_dir()
         self.init_config_files()
         self.load_config_file()
         # enforce cl-opts override configfile opts:
         self.update_config(cl_config)
 

IPython/core/extensions.py

@@ -1,189 +1,175 b''
 # encoding: utf-8
-"""A class for managing IPython extensions.
+"""A class for managing IPython extensions."""
 
-Authors:
-
-* Brian Granger
-"""
-
-#-----------------------------------------------------------------------------
-#  Copyright (C) 2010-2011  The IPython Development Team
-#
-#  Distributed under the terms of the BSD License.  The full license is in
-#  the file COPYING, distributed as part of this software.
-#-----------------------------------------------------------------------------
-
-#-----------------------------------------------------------------------------
-# Imports
-#-----------------------------------------------------------------------------
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
 
 import os
 from shutil import copyfile
 import sys
 
 from IPython.config.configurable import Configurable
+from IPython.utils.path import ensure_dir_exists
 from IPython.utils.traitlets import Instance
 from IPython.utils.py3compat import PY3
 if PY3:
     from imp import reload
 
 #-----------------------------------------------------------------------------
 # Main class
 #-----------------------------------------------------------------------------
 
 class ExtensionManager(Configurable):
     """A class to manage IPython extensions.
 
     An IPython extension is an importable Python module that has
     a function with the signature::
 
         def load_ipython_extension(ipython):
             # Do things with ipython
 
     This function is called after your extension is imported and the
     currently active :class:`InteractiveShell` instance is passed as
     the only argument.  You can do anything you want with IPython at
     that point, including defining new magic and aliases, adding new
     components, etc.
     
     You can also optionally define an :func:`unload_ipython_extension(ipython)`
     function, which will be called if the user unloads or reloads the extension.
     The extension manager will only call :func:`load_ipython_extension` again
     if the extension is reloaded.
 
     You can put your extension modules anywhere you want, as long as
     they can be imported by Python's standard import mechanism.  However,
     to make it easy to write extensions, you can also put your extensions
     in ``os.path.join(self.ipython_dir, 'extensions')``.  This directory
     is added to ``sys.path`` automatically.
     """
 
     shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
 
     def __init__(self, shell=None, **kwargs):
         super(ExtensionManager, self).__init__(shell=shell, **kwargs)
         self.shell.on_trait_change(
             self._on_ipython_dir_changed, 'ipython_dir'
         )
         self.loaded = set()
 
     def __del__(self):
         self.shell.on_trait_change(
             self._on_ipython_dir_changed, 'ipython_dir', remove=True
         )
 
     @property
     def ipython_extension_dir(self):
         return os.path.join(self.shell.ipython_dir, u'extensions')
 
     def _on_ipython_dir_changed(self):
-        if not os.path.isdir(self.ipython_extension_dir):
-            os.makedirs(self.ipython_extension_dir, mode = 0o777)
+        ensure_dir_exists(self.ipython_extension_dir)
 
     def load_extension(self, module_str):
         """Load an IPython extension by its module name.
 
         Returns the string "already loaded" if the extension is already loaded,
         "no load function" if the module doesn't have a load_ipython_extension
         function, or None if it succeeded.
         """
         if module_str in self.loaded:
             return "already loaded"
         
         from IPython.utils.syspathcontext import prepended_to_syspath
         
         with self.shell.builtin_trap:
             if module_str not in sys.modules:
                 with prepended_to_syspath(self.ipython_extension_dir):
                     __import__(module_str)
             mod = sys.modules[module_str]
             if self._call_load_ipython_extension(mod):
                 self.loaded.add(module_str)
             else:
                 return "no load function"
 
     def unload_extension(self, module_str):
         """Unload an IPython extension by its module name.
 
         This function looks up the extension's name in ``sys.modules`` and
         simply calls ``mod.unload_ipython_extension(self)``.
         
         Returns the string "no unload function" if the extension doesn't define
         a function to unload itself, "not loaded" if the extension isn't loaded,
         otherwise None.
         """
         if module_str not in self.loaded:
             return "not loaded"
         
         if module_str in sys.modules:
             mod = sys.modules[module_str]
             if self._call_unload_ipython_extension(mod):
                 self.loaded.discard(module_str)
             else:
                 return "no unload function"
 
     def reload_extension(self, module_str):
         """Reload an IPython extension by calling reload.
 
         If the module has not been loaded before,
         :meth:`InteractiveShell.load_extension` is called. Otherwise
         :func:`reload` is called and then the :func:`load_ipython_extension`
         function of the module, if it exists is called.
         """
         from IPython.utils.syspathcontext import prepended_to_syspath
 
         if (module_str in self.loaded) and (module_str in sys.modules):
             self.unload_extension(module_str)
             mod = sys.modules[module_str]
             with prepended_to_syspath(self.ipython_extension_dir):
                 reload(mod)
             if self._call_load_ipython_extension(mod):
                 self.loaded.add(module_str)
         else:
             self.load_extension(module_str)
 
     def _call_load_ipython_extension(self, mod):
         if hasattr(mod, 'load_ipython_extension'):
             mod.load_ipython_extension(self.shell)
             return True
 
     def _call_unload_ipython_extension(self, mod):
         if hasattr(mod, 'unload_ipython_extension'):
             mod.unload_ipython_extension(self.shell)
             return True
 
     def install_extension(self, url, filename=None):
         """Download and install an IPython extension. 
 
         If filename is given, the file will be so named (inside the extension
         directory). Otherwise, the name from the URL will be used. The file must
         have a .py or .zip extension; otherwise, a ValueError will be raised.
 
         Returns the full path to the installed file.
         """
         # Ensure the extension directory exists
-        if not os.path.isdir(self.ipython_extension_dir):
-            os.makedirs(self.ipython_extension_dir, mode = 0o777)
+        ensure_dir_exists(self.ipython_extension_dir)
 
         if os.path.isfile(url):
             src_filename = os.path.basename(url)
             copy = copyfile
         else:
             # Deferred imports
             try:
                 from urllib.parse import urlparse  # Py3
                 from urllib.request import urlretrieve
             except ImportError:
                 from urlparse import urlparse
                 from urllib import urlretrieve
             src_filename = urlparse(url).path.split('/')[-1]
             copy = urlretrieve
 
         if filename is None:
             filename = src_filename
         if os.path.splitext(filename)[1] not in ('.py', '.zip'):
             raise ValueError("The file must have a .py or .zip extension", filename)
 
         filename = os.path.join(self.ipython_extension_dir, filename)
         copy(url, filename)
         return filename

IPython/core/interactiveshell.py

@@ -1,3224 +1,3223 b''
 # -*- coding: utf-8 -*-
 """Main IPython class."""
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2001 Janko Hauser <[e-mail]>
 #  Copyright (C) 2001-2007 Fernando Perez. <[e-mail]>
 #  Copyright (C) 2008-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 from __future__ import absolute_import
 from __future__ import print_function
 
 import __future__
 import abc
 import ast
 import atexit
 import functools
 import os
 import re
 import runpy
 import sys
 import tempfile
 import types
 import subprocess
 from io import open as io_open
 
 from IPython.config.configurable import SingletonConfigurable
 from IPython.core import debugger, oinspect
 from IPython.core import magic
 from IPython.core import page
 from IPython.core import prefilter
 from IPython.core import shadowns
 from IPython.core import ultratb
 from IPython.core.alias import AliasManager, AliasError
 from IPython.core.autocall import ExitAutocall
 from IPython.core.builtin_trap import BuiltinTrap
 from IPython.core.events import EventManager, available_events
 from IPython.core.compilerop import CachingCompiler, check_linecache_ipython
 from IPython.core.display_trap import DisplayTrap
 from IPython.core.displayhook import DisplayHook
 from IPython.core.displaypub import DisplayPublisher
 from IPython.core.error import UsageError
 from IPython.core.extensions import ExtensionManager
 from IPython.core.formatters import DisplayFormatter
 from IPython.core.history import HistoryManager
 from IPython.core.inputsplitter import IPythonInputSplitter, ESC_MAGIC, ESC_MAGIC2
 from IPython.core.logger import Logger
 from IPython.core.macro import Macro
 from IPython.core.payload import PayloadManager
 from IPython.core.prefilter import PrefilterManager
 from IPython.core.profiledir import ProfileDir
 from IPython.core.prompts import PromptManager
 from IPython.lib.latextools import LaTeXTool
 from IPython.testing.skipdoctest import skip_doctest
 from IPython.utils import PyColorize
 from IPython.utils import io
 from IPython.utils import py3compat
 from IPython.utils import openpy
 from IPython.utils.decorators import undoc
 from IPython.utils.io import ask_yes_no
 from IPython.utils.ipstruct import Struct
-from IPython.utils.path import get_home_dir, get_ipython_dir, get_py_filename, unquote_filename
+from IPython.utils.path import get_home_dir, get_ipython_dir, get_py_filename, unquote_filename, ensure_dir_exists
 from IPython.utils.pickleshare import PickleShareDB
 from IPython.utils.process import system, getoutput
 from IPython.utils.py3compat import (builtin_mod, unicode_type, string_types,
                                      with_metaclass, iteritems)
 from IPython.utils.strdispatch import StrDispatch
 from IPython.utils.syspathcontext import prepended_to_syspath
 from IPython.utils.text import (format_screen, LSString, SList,
                                 DollarFormatter)
 from IPython.utils.traitlets import (Integer, CBool, CaselessStrEnum, Enum,
                                      List, Unicode, Instance, Type)
 from IPython.utils.warn import warn, error
 import IPython.core.hooks
 
 #-----------------------------------------------------------------------------
 # Globals
 #-----------------------------------------------------------------------------
 
 # compiled regexps for autoindent management
 dedent_re = re.compile(r'^\s+raise|^\s+return|^\s+pass')
 
 #-----------------------------------------------------------------------------
 # Utilities
 #-----------------------------------------------------------------------------
 
 @undoc
 def softspace(file, newvalue):
     """Copied from code.py, to remove the dependency"""
 
     oldvalue = 0
     try:
         oldvalue = file.softspace
     except AttributeError:
         pass
     try:
         file.softspace = newvalue
     except (AttributeError, TypeError):
         # "attribute-less object" or "read-only attributes"
         pass
     return oldvalue
 
 @undoc
 def no_op(*a, **kw): pass
 
 @undoc
 class NoOpContext(object):
     def __enter__(self): pass
     def __exit__(self, type, value, traceback): pass
 no_op_context = NoOpContext()
 
 class SpaceInInput(Exception): pass
 
 @undoc
 class Bunch: pass
 
 
 def get_default_colors():
     if sys.platform=='darwin':
         return "LightBG"
     elif os.name=='nt':
         return 'Linux'
     else:
         return 'Linux'
 
 
 class SeparateUnicode(Unicode):
     r"""A Unicode subclass to validate separate_in, separate_out, etc.
 
     This is a Unicode based trait that converts '0'->'' and ``'\\n'->'\n'``.
     """
 
     def validate(self, obj, value):
         if value == '0': value = ''
         value = value.replace('\\n','\n')
         return super(SeparateUnicode, self).validate(obj, value)
 
 
 class ReadlineNoRecord(object):
     """Context manager to execute some code, then reload readline history
     so that interactive input to the code doesn't appear when pressing up."""
     def __init__(self, shell):
         self.shell = shell
         self._nested_level = 0
 
     def __enter__(self):
         if self._nested_level == 0:
             try:
                 self.orig_length = self.current_length()
                 self.readline_tail = self.get_readline_tail()
             except (AttributeError, IndexError):   # Can fail with pyreadline
                 self.orig_length, self.readline_tail = 999999, []
         self._nested_level += 1
 
     def __exit__(self, type, value, traceback):
         self._nested_level -= 1
         if self._nested_level == 0:
             # Try clipping the end if it's got longer
             try:
                 e = self.current_length() - self.orig_length
                 if e > 0:
                     for _ in range(e):
                         self.shell.readline.remove_history_item(self.orig_length)
 
                 # If it still doesn't match, just reload readline history.
                 if self.current_length() != self.orig_length \
                     or self.get_readline_tail() != self.readline_tail:
                     self.shell.refill_readline_hist()
             except (AttributeError, IndexError):
                 pass
         # Returning False will cause exceptions to propagate
         return False
 
     def current_length(self):
         return self.shell.readline.get_current_history_length()
 
     def get_readline_tail(self, n=10):
         """Get the last n items in readline history."""
         end = self.shell.readline.get_current_history_length() + 1
         start = max(end-n, 1)
         ghi = self.shell.readline.get_history_item
         return [ghi(x) for x in range(start, end)]
 
 
 @undoc
 class DummyMod(object):
     """A dummy module used for IPython's interactive module when
     a namespace must be assigned to the module's __dict__."""
     pass
 
 #-----------------------------------------------------------------------------
 # Main IPython class
 #-----------------------------------------------------------------------------
 
 class InteractiveShell(SingletonConfigurable):
     """An enhanced, interactive shell for Python."""
 
     _instance = None
     
     ast_transformers = List([], config=True, help=
         """
         A list of ast.NodeTransformer subclass instances, which will be applied
         to user input before code is run.
         """
     )
 
     autocall = Enum((0,1,2), default_value=0, config=True, help=
         """
         Make IPython automatically call any callable object even if you didn't
         type explicit parentheses. For example, 'str 43' becomes 'str(43)'
         automatically. The value can be '0' to disable the feature, '1' for
         'smart' autocall, where it is not applied if there are no more
         arguments on the line, and '2' for 'full' autocall, where all callable
         objects are automatically called (even if no arguments are present).
         """
     )
     # TODO: remove all autoindent logic and put into frontends.
     # We can't do this yet because even runlines uses the autoindent.
     autoindent = CBool(True, config=True, help=
         """
         Autoindent IPython code entered interactively.
         """
     )
     automagic = CBool(True, config=True, help=
         """
         Enable magic commands to be called without the leading %.
         """
     )
     cache_size = Integer(1000, config=True, help=
         """
         Set the size of the output cache.  The default is 1000, you can
         change it permanently in your config file.  Setting it to 0 completely
         disables the caching system, and the minimum value accepted is 20 (if
         you provide a value less than 20, it is reset to 0 and a warning is
         issued).  This limit is defined because otherwise you'll spend more
         time re-flushing a too small cache than working
         """
     )
     color_info = CBool(True, config=True, help=
         """
         Use colors for displaying information about objects. Because this
         information is passed through a pager (like 'less'), and some pagers
         get confused with color codes, this capability can be turned off.
         """
     )
     colors = CaselessStrEnum(('NoColor','LightBG','Linux'),
                              default_value=get_default_colors(), config=True,
         help="Set the color scheme (NoColor, Linux, or LightBG)."
     )
     colors_force = CBool(False, help=
         """
         Force use of ANSI color codes, regardless of OS and readline
         availability.
         """
         # FIXME: This is essentially a hack to allow ZMQShell to show colors
         # without readline on Win32. When the ZMQ formatting system is
         # refactored, this should be removed.
     )
     debug = CBool(False, config=True)
     deep_reload = CBool(False, config=True, help=
         """
         Enable deep (recursive) reloading by default. IPython can use the
         deep_reload module which reloads changes in modules recursively (it
         replaces the reload() function, so you don't need to change anything to
         use it). deep_reload() forces a full reload of modules whose code may
         have changed, which the default reload() function does not.  When
         deep_reload is off, IPython will use the normal reload(), but
         deep_reload will still be available as dreload().
         """
     )
     disable_failing_post_execute = CBool(False, config=True,
         help="Don't call post-execute functions that have failed in the past."
     )
     display_formatter = Instance(DisplayFormatter)
     displayhook_class = Type(DisplayHook)
     display_pub_class = Type(DisplayPublisher)
     data_pub_class = None
 
     exit_now = CBool(False)
     exiter = Instance(ExitAutocall)
     def _exiter_default(self):
         return ExitAutocall(self)
     # Monotonically increasing execution counter
     execution_count = Integer(1)
     filename = Unicode("<ipython console>")
     ipython_dir= Unicode('', config=True) # Set to get_ipython_dir() in __init__
 
     # Input splitter, to transform input line by line and detect when a block
     # is ready to be executed.
     input_splitter = Instance('IPython.core.inputsplitter.IPythonInputSplitter',
                               (), {'line_input_checker': True})
     
     # This InputSplitter instance is used to transform completed cells before
     # running them. It allows cell magics to contain blank lines.
     input_transformer_manager = Instance('IPython.core.inputsplitter.IPythonInputSplitter',
                                          (), {'line_input_checker': False})
     
     logstart = CBool(False, config=True, help=
         """
         Start logging to the default log file.
         """
     )
     logfile = Unicode('', config=True, help=
         """
         The name of the logfile to use.
         """
     )
     logappend = Unicode('', config=True, help=
         """
         Start logging to the given file in append mode.
         """
     )
     object_info_string_level = Enum((0,1,2), default_value=0,
                                     config=True)
     pdb = CBool(False, config=True, help=
         """
         Automatically call the pdb debugger after every exception.
         """
     )
     multiline_history = CBool(sys.platform != 'win32', config=True,
         help="Save multi-line entries as one entry in readline history"
     )
 
     # deprecated prompt traits:
     
     prompt_in1 = Unicode('In [\\#]: ', config=True,
         help="Deprecated, use PromptManager.in_template")
     prompt_in2 = Unicode('   .\\D.: ', config=True,
         help="Deprecated, use PromptManager.in2_template")
     prompt_out = Unicode('Out[\\#]: ', config=True,
         help="Deprecated, use PromptManager.out_template")
     prompts_pad_left = CBool(True, config=True,
         help="Deprecated, use PromptManager.justify")
     
     def _prompt_trait_changed(self, name, old, new):
         table = {
             'prompt_in1' : 'in_template',
             'prompt_in2' : 'in2_template',
             'prompt_out' : 'out_template',
             'prompts_pad_left' : 'justify',
         }
         warn("InteractiveShell.{name} is deprecated, use PromptManager.{newname}".format(
                 name=name, newname=table[name])
         )
         # protect against weird cases where self.config may not exist:
         if self.config is not None:
             # propagate to corresponding PromptManager trait
             setattr(self.config.PromptManager, table[name], new)
     
     _prompt_in1_changed = _prompt_trait_changed
     _prompt_in2_changed = _prompt_trait_changed
     _prompt_out_changed = _prompt_trait_changed
     _prompt_pad_left_changed = _prompt_trait_changed
     
     show_rewritten_input = CBool(True, config=True,
         help="Show rewritten input, e.g. for autocall."
     )
     
     quiet = CBool(False, config=True)
 
     history_length = Integer(10000, config=True)
 
     # The readline stuff will eventually be moved to the terminal subclass
     # but for now, we can't do that as readline is welded in everywhere.
     readline_use = CBool(True, config=True)
     readline_remove_delims = Unicode('-/~', config=True)
     readline_delims = Unicode() # set by init_readline()
     # don't use \M- bindings by default, because they
     # conflict with 8-bit encodings. See gh-58,gh-88
     readline_parse_and_bind = List([
             'tab: complete',
             '"\C-l": clear-screen',
             'set show-all-if-ambiguous on',
             '"\C-o": tab-insert',
             '"\C-r": reverse-search-history',
             '"\C-s": forward-search-history',
             '"\C-p": history-search-backward',
             '"\C-n": history-search-forward',
             '"\e[A": history-search-backward',
             '"\e[B": history-search-forward',
             '"\C-k": kill-line',
             '"\C-u": unix-line-discard',
         ], allow_none=False, config=True)
 
     ast_node_interactivity = Enum(['all', 'last', 'last_expr', 'none'],
                                   default_value='last_expr', config=True, 
                                   help="""
         'all', 'last', 'last_expr' or 'none', specifying which nodes should be
         run interactively (displaying output from expressions).""")
 
     # TODO: this part of prompt management should be moved to the frontends.
     # Use custom TraitTypes that convert '0'->'' and '\\n'->'\n'
     separate_in = SeparateUnicode('\n', config=True)
     separate_out = SeparateUnicode('', config=True)
     separate_out2 = SeparateUnicode('', config=True)
     wildcards_case_sensitive = CBool(True, config=True)
     xmode = CaselessStrEnum(('Context','Plain', 'Verbose'),
                             default_value='Context', config=True)
 
     # Subcomponents of InteractiveShell
     alias_manager = Instance('IPython.core.alias.AliasManager')
     prefilter_manager = Instance('IPython.core.prefilter.PrefilterManager')
     builtin_trap = Instance('IPython.core.builtin_trap.BuiltinTrap')
     display_trap = Instance('IPython.core.display_trap.DisplayTrap')
     extension_manager = Instance('IPython.core.extensions.ExtensionManager')
     payload_manager = Instance('IPython.core.payload.PayloadManager')
     history_manager = Instance('IPython.core.history.HistoryManager')
     magics_manager = Instance('IPython.core.magic.MagicsManager')
 
     profile_dir = Instance('IPython.core.application.ProfileDir')
     @property
     def profile(self):
         if self.profile_dir is not None:
             name = os.path.basename(self.profile_dir.location)
             return name.replace('profile_','')
 
 
     # Private interface
     _post_execute = Instance(dict)
 
     # Tracks any GUI loop loaded for pylab
     pylab_gui_select = None
 
     def __init__(self, ipython_dir=None, profile_dir=None,
                  user_module=None, user_ns=None,
                  custom_exceptions=((), None), **kwargs):
 
         # This is where traits with a config_key argument are updated
         # from the values on config.
         super(InteractiveShell, self).__init__(**kwargs)
         self.configurables = [self]
 
         # These are relatively independent and stateless
         self.init_ipython_dir(ipython_dir)
         self.init_profile_dir(profile_dir)
         self.init_instance_attrs()
         self.init_environment()
         
         # Check if we're in a virtualenv, and set up sys.path.
         self.init_virtualenv()
 
         # Create namespaces (user_ns, user_global_ns, etc.)
         self.init_create_namespaces(user_module, user_ns)
         # This has to be done after init_create_namespaces because it uses
         # something in self.user_ns, but before init_sys_modules, which
         # is the first thing to modify sys.
         # TODO: When we override sys.stdout and sys.stderr before this class
         # is created, we are saving the overridden ones here. Not sure if this
         # is what we want to do.
         self.save_sys_module_state()
         self.init_sys_modules()
 
         # While we're trying to have each part of the code directly access what
         # it needs without keeping redundant references to objects, we have too
         # much legacy code that expects ip.db to exist.
         self.db = PickleShareDB(os.path.join(self.profile_dir.location, 'db'))
 
         self.init_history()
         self.init_encoding()
         self.init_prefilter()
 
         self.init_syntax_highlighting()
         self.init_hooks()
         self.init_events()
         self.init_pushd_popd_magic()
         # self.init_traceback_handlers use to be here, but we moved it below
         # because it and init_io have to come after init_readline.
         self.init_user_ns()
         self.init_logger()
         self.init_builtins()
 
         # The following was in post_config_initialization
         self.init_inspector()
         # init_readline() must come before init_io(), because init_io uses
         # readline related things.
         self.init_readline()
         # We save this here in case user code replaces raw_input, but it needs
         # to be after init_readline(), because PyPy's readline works by replacing
         # raw_input.
         if py3compat.PY3:
             self.raw_input_original = input
         else:
             self.raw_input_original = raw_input
         # init_completer must come after init_readline, because it needs to
         # know whether readline is present or not system-wide to configure the
         # completers, since the completion machinery can now operate
         # independently of readline (e.g. over the network)
         self.init_completer()
         # TODO: init_io() needs to happen before init_traceback handlers
         # because the traceback handlers hardcode the stdout/stderr streams.
         # This logic in in debugger.Pdb and should eventually be changed.
         self.init_io()
         self.init_traceback_handlers(custom_exceptions)
         self.init_prompts()
         self.init_display_formatter()
         self.init_display_pub()
         self.init_data_pub()
         self.init_displayhook()
         self.init_latextool()
         self.init_magics()
         self.init_alias()
         self.init_logstart()
         self.init_pdb()
         self.init_extension_manager()
         self.init_payload()
         self.init_comms()
         self.hooks.late_startup_hook()
         self.events.trigger('shell_initialized', self)
         atexit.register(self.atexit_operations)
 
     def get_ipython(self):
         """Return the currently running IPython instance."""
         return self
 
     #-------------------------------------------------------------------------
     # Trait changed handlers
     #-------------------------------------------------------------------------
 
     def _ipython_dir_changed(self, name, new):
-        if not os.path.isdir(new):
-            os.makedirs(new, mode = 0o777)
+        ensure_dir_exists(new)
 
     def set_autoindent(self,value=None):
         """Set the autoindent flag, checking for readline support.
 
         If called with no arguments, it acts as a toggle."""
 
         if value != 0 and not self.has_readline:
             if os.name == 'posix':
                 warn("The auto-indent feature requires the readline library")
             self.autoindent = 0
             return
         if value is None:
             self.autoindent = not self.autoindent
         else:
             self.autoindent = value
 
     #-------------------------------------------------------------------------
     # init_* methods called by __init__
     #-------------------------------------------------------------------------
 
     def init_ipython_dir(self, ipython_dir):
         if ipython_dir is not None:
             self.ipython_dir = ipython_dir
             return
 
         self.ipython_dir = get_ipython_dir()
 
     def init_profile_dir(self, profile_dir):
         if profile_dir is not None:
             self.profile_dir = profile_dir
             return
         self.profile_dir =\
             ProfileDir.create_profile_dir_by_name(self.ipython_dir, 'default')
 
     def init_instance_attrs(self):
         self.more = False
 
         # command compiler
         self.compile = CachingCompiler()
 
         # Make an empty namespace, which extension writers can rely on both
         # existing and NEVER being used by ipython itself.  This gives them a
         # convenient location for storing additional information and state
         # their extensions may require, without fear of collisions with other
         # ipython names that may develop later.
         self.meta = Struct()
 
         # Temporary files used for various purposes.  Deleted at exit.
         self.tempfiles = []
         self.tempdirs = []
 
         # Keep track of readline usage (later set by init_readline)
         self.has_readline = False
 
         # keep track of where we started running (mainly for crash post-mortem)
         # This is not being used anywhere currently.
         self.starting_dir = py3compat.getcwd()
 
         # Indentation management
         self.indent_current_nsp = 0
 
         # Dict to track post-execution functions that have been registered
         self._post_execute = {}
 
     def init_environment(self):
         """Any changes we need to make to the user's environment."""
         pass
 
     def init_encoding(self):
         # Get system encoding at startup time.  Certain terminals (like Emacs
         # under Win32 have it set to None, and we need to have a known valid
         # encoding to use in the raw_input() method
         try:
             self.stdin_encoding = sys.stdin.encoding or 'ascii'
         except AttributeError:
             self.stdin_encoding = 'ascii'
 
     def init_syntax_highlighting(self):
         # Python source parser/formatter for syntax highlighting
         pyformat = PyColorize.Parser().format
         self.pycolorize = lambda src: pyformat(src,'str',self.colors)
 
     def init_pushd_popd_magic(self):
         # for pushd/popd management
         self.home_dir = get_home_dir()
 
         self.dir_stack = []
 
     def init_logger(self):
         self.logger = Logger(self.home_dir, logfname='ipython_log.py',
                              logmode='rotate')
 
     def init_logstart(self):
         """Initialize logging in case it was requested at the command line.
         """
         if self.logappend:
             self.magic('logstart %s append' % self.logappend)
         elif self.logfile:
             self.magic('logstart %s' % self.logfile)
         elif self.logstart:
             self.magic('logstart')
 
     def init_builtins(self):
         # A single, static flag that we set to True.  Its presence indicates
         # that an IPython shell has been created, and we make no attempts at
         # removing on exit or representing the existence of more than one
         # IPython at a time.
         builtin_mod.__dict__['__IPYTHON__'] = True
 
         # In 0.11 we introduced '__IPYTHON__active' as an integer we'd try to
         # manage on enter/exit, but with all our shells it's virtually
         # impossible to get all the cases right.  We're leaving the name in for
         # those who adapted their codes to check for this flag, but will
         # eventually remove it after a few more releases.
         builtin_mod.__dict__['__IPYTHON__active'] = \
                                           'Deprecated, check for __IPYTHON__'
 
         self.builtin_trap = BuiltinTrap(shell=self)
 
     def init_inspector(self):
         # Object inspector
         self.inspector = oinspect.Inspector(oinspect.InspectColors,
                                             PyColorize.ANSICodeColors,
                                             'NoColor',
                                             self.object_info_string_level)
 
     def init_io(self):
         # This will just use sys.stdout and sys.stderr. If you want to
         # override sys.stdout and sys.stderr themselves, you need to do that
         # *before* instantiating this class, because io holds onto
         # references to the underlying streams.
         if (sys.platform == 'win32' or sys.platform == 'cli') and self.has_readline:
             io.stdout = io.stderr = io.IOStream(self.readline._outputfile)
         else:
             io.stdout = io.IOStream(sys.stdout)
             io.stderr = io.IOStream(sys.stderr)
 
     def init_prompts(self):
         self.prompt_manager = PromptManager(shell=self, parent=self)
         self.configurables.append(self.prompt_manager)
         # Set system prompts, so that scripts can decide if they are running
         # interactively.
         sys.ps1 = 'In : '
         sys.ps2 = '...: '
         sys.ps3 = 'Out: '
 
     def init_display_formatter(self):
         self.display_formatter = DisplayFormatter(parent=self)
         self.configurables.append(self.display_formatter)
 
     def init_display_pub(self):
         self.display_pub = self.display_pub_class(parent=self)
         self.configurables.append(self.display_pub)
 
     def init_data_pub(self):
         if not self.data_pub_class:
             self.data_pub = None
             return
         self.data_pub = self.data_pub_class(parent=self)
         self.configurables.append(self.data_pub)
 
     def init_displayhook(self):
         # Initialize displayhook, set in/out prompts and printing system
         self.displayhook = self.displayhook_class(
             parent=self,
             shell=self,
             cache_size=self.cache_size,
         )
         self.configurables.append(self.displayhook)
         # This is a context manager that installs/revmoes the displayhook at
         # the appropriate time.
         self.display_trap = DisplayTrap(hook=self.displayhook)
 
     def init_latextool(self):
         """Configure LaTeXTool."""
         cfg = LaTeXTool.instance(parent=self)
         if cfg not in self.configurables:
             self.configurables.append(cfg)
 
     def init_virtualenv(self):
         """Add a virtualenv to sys.path so the user can import modules from it.
         This isn't perfect: it doesn't use the Python interpreter with which the
         virtualenv was built, and it ignores the --no-site-packages option. A
         warning will appear suggesting the user installs IPython in the
         virtualenv, but for many cases, it probably works well enough.
         
         Adapted from code snippets online.
         
         http://blog.ufsoft.org/2009/1/29/ipython-and-virtualenv
         """
         if 'VIRTUAL_ENV' not in os.environ:
             # Not in a virtualenv
             return
         
         # venv detection:
         # stdlib venv may symlink sys.executable, so we can't use realpath.
         # but others can symlink *to* the venv Python, so we can't just use sys.executable.
         # So we just check every item in the symlink tree (generally <= 3)
         p = sys.executable
         paths = [p]
         while os.path.islink(p):
             p = os.path.join(os.path.dirname(p), os.readlink(p))
             paths.append(p)
         if any(p.startswith(os.environ['VIRTUAL_ENV']) for p in paths):
             # Running properly in the virtualenv, don't need to do anything
             return
         
         warn("Attempting to work in a virtualenv. If you encounter problems, please "
              "install IPython inside the virtualenv.")
         if sys.platform == "win32":
             virtual_env = os.path.join(os.environ['VIRTUAL_ENV'], 'Lib', 'site-packages') 
         else:
             virtual_env = os.path.join(os.environ['VIRTUAL_ENV'], 'lib',
                        'python%d.%d' % sys.version_info[:2], 'site-packages')
         
         import site
         sys.path.insert(0, virtual_env)
         site.addsitedir(virtual_env)
 
     #-------------------------------------------------------------------------
     # Things related to injections into the sys module
     #-------------------------------------------------------------------------
 
     def save_sys_module_state(self):
         """Save the state of hooks in the sys module.
 
         This has to be called after self.user_module is created.
         """
         self._orig_sys_module_state = {}
         self._orig_sys_module_state['stdin'] = sys.stdin
         self._orig_sys_module_state['stdout'] = sys.stdout
         self._orig_sys_module_state['stderr'] = sys.stderr
         self._orig_sys_module_state['excepthook'] = sys.excepthook
         self._orig_sys_modules_main_name = self.user_module.__name__
         self._orig_sys_modules_main_mod = sys.modules.get(self.user_module.__name__)
 
     def restore_sys_module_state(self):
         """Restore the state of the sys module."""
         try:
             for k, v in iteritems(self._orig_sys_module_state):
                 setattr(sys, k, v)
         except AttributeError:
             pass
         # Reset what what done in self.init_sys_modules
         if self._orig_sys_modules_main_mod is not None:
             sys.modules[self._orig_sys_modules_main_name] = self._orig_sys_modules_main_mod
 
     #-------------------------------------------------------------------------
     # Things related to hooks
     #-------------------------------------------------------------------------
 
     def init_hooks(self):
         # hooks holds pointers used for user-side customizations
         self.hooks = Struct()
 
         self.strdispatchers = {}
 
         # Set all default hooks, defined in the IPython.hooks module.
         hooks = IPython.core.hooks
         for hook_name in hooks.__all__:
             # default hooks have priority 100, i.e. low; user hooks should have
             # 0-100 priority
             self.set_hook(hook_name,getattr(hooks,hook_name), 100, _warn_deprecated=False)
 
     def set_hook(self,name,hook, priority=50, str_key=None, re_key=None,
                  _warn_deprecated=True):
         """set_hook(name,hook) -> sets an internal IPython hook.
 
         IPython exposes some of its internal API as user-modifiable hooks.  By
         adding your function to one of these hooks, you can modify IPython's
         behavior to call at runtime your own routines."""
 
         # At some point in the future, this should validate the hook before it
         # accepts it.  Probably at least check that the hook takes the number
         # of args it's supposed to.
 
         f = types.MethodType(hook,self)
 
         # check if the hook is for strdispatcher first
         if str_key is not None:
             sdp = self.strdispatchers.get(name, StrDispatch())
             sdp.add_s(str_key, f, priority )
             self.strdispatchers[name] = sdp
             return
         if re_key is not None:
             sdp = self.strdispatchers.get(name, StrDispatch())
             sdp.add_re(re.compile(re_key), f, priority )
             self.strdispatchers[name] = sdp
             return
 
         dp = getattr(self.hooks, name, None)
         if name not in IPython.core.hooks.__all__:
             print("Warning! Hook '%s' is not one of %s" % \
                   (name, IPython.core.hooks.__all__ ))
 
         if _warn_deprecated and (name in IPython.core.hooks.deprecated):
             alternative = IPython.core.hooks.deprecated[name]
             warn("Hook {} is deprecated. Use {} instead.".format(name, alternative))
 
         if not dp:
             dp = IPython.core.hooks.CommandChainDispatcher()
 
         try:
             dp.add(f,priority)
         except AttributeError:
             # it was not commandchain, plain old func - replace
             dp = f
 
         setattr(self.hooks,name, dp)
 
     #-------------------------------------------------------------------------
     # Things related to events
     #-------------------------------------------------------------------------
 
     def init_events(self):
         self.events = EventManager(self, available_events)
 
     def register_post_execute(self, func):
         """DEPRECATED: Use ip.events.register('post_run_cell', func)
         
         Register a function for calling after code execution.
         """
         warn("ip.register_post_execute is deprecated, use "
              "ip.events.register('post_run_cell', func) instead.")
         self.events.register('post_run_cell', func)
     
     #-------------------------------------------------------------------------
     # Things related to the "main" module
     #-------------------------------------------------------------------------
 
     def new_main_mod(self, filename, modname):
         """Return a new 'main' module object for user code execution.
         
         ``filename`` should be the path of the script which will be run in the
         module. Requests with the same filename will get the same module, with
         its namespace cleared.
         
         ``modname`` should be the module name - normally either '__main__' or
         the basename of the file without the extension.
         
         When scripts are executed via %run, we must keep a reference to their
         __main__ module around so that Python doesn't
         clear it, rendering references to module globals useless.
 
         This method keeps said reference in a private dict, keyed by the
         absolute path of the script. This way, for multiple executions of the
         same script we only keep one copy of the namespace (the last one),
         thus preventing memory leaks from old references while allowing the
         objects from the last execution to be accessible.
         """
         filename = os.path.abspath(filename)
         try:
             main_mod = self._main_mod_cache[filename]
         except KeyError:
             main_mod = self._main_mod_cache[filename] = types.ModuleType(modname,
                         doc="Module created for script run in IPython")
         else:
             main_mod.__dict__.clear()
             main_mod.__name__ = modname
         
         main_mod.__file__ = filename
         # It seems pydoc (and perhaps others) needs any module instance to
         # implement a __nonzero__ method
         main_mod.__nonzero__ = lambda : True
         
         return main_mod
 
     def clear_main_mod_cache(self):
         """Clear the cache of main modules.
 
         Mainly for use by utilities like %reset.
 
         Examples
         --------
 
         In [15]: import IPython
 
         In [16]: m = _ip.new_main_mod(IPython.__file__, 'IPython')
 
         In [17]: len(_ip._main_mod_cache) > 0
         Out[17]: True
 
         In [18]: _ip.clear_main_mod_cache()
 
         In [19]: len(_ip._main_mod_cache) == 0
         Out[19]: True
         """
         self._main_mod_cache.clear()
 
     #-------------------------------------------------------------------------
     # Things related to debugging
     #-------------------------------------------------------------------------
 
     def init_pdb(self):
         # Set calling of pdb on exceptions
         # self.call_pdb is a property
         self.call_pdb = self.pdb
 
     def _get_call_pdb(self):
         return self._call_pdb
 
     def _set_call_pdb(self,val):
 
         if val not in (0,1,False,True):
             raise ValueError('new call_pdb value must be boolean')
 
         # store value in instance
         self._call_pdb = val
 
         # notify the actual exception handlers
         self.InteractiveTB.call_pdb = val
 
     call_pdb = property(_get_call_pdb,_set_call_pdb,None,
                         'Control auto-activation of pdb at exceptions')
 
     def debugger(self,force=False):
         """Call the pydb/pdb debugger.
 
         Keywords:
 
           - force(False): by default, this routine checks the instance call_pdb
             flag and does not actually invoke the debugger if the flag is false.
             The 'force' option forces the debugger to activate even if the flag
             is false.
         """
 
         if not (force or self.call_pdb):
             return
 
         if not hasattr(sys,'last_traceback'):
             error('No traceback has been produced, nothing to debug.')
             return
 
         # use pydb if available
         if debugger.has_pydb:
             from pydb import pm
         else:
             # fallback to our internal debugger
             pm = lambda : self.InteractiveTB.debugger(force=True)
 
         with self.readline_no_record:
             pm()
 
     #-------------------------------------------------------------------------
     # Things related to IPython's various namespaces
     #-------------------------------------------------------------------------
     default_user_namespaces = True
 
     def init_create_namespaces(self, user_module=None, user_ns=None):
         # Create the namespace where the user will operate.  user_ns is
         # normally the only one used, and it is passed to the exec calls as
         # the locals argument.  But we do carry a user_global_ns namespace
         # given as the exec 'globals' argument,  This is useful in embedding
         # situations where the ipython shell opens in a context where the
         # distinction between locals and globals is meaningful.  For
         # non-embedded contexts, it is just the same object as the user_ns dict.
 
         # FIXME. For some strange reason, __builtins__ is showing up at user
         # level as a dict instead of a module. This is a manual fix, but I
         # should really track down where the problem is coming from. Alex
         # Schmolck reported this problem first.
 
         # A useful post by Alex Martelli on this topic:
         # Re: inconsistent value from __builtins__
         # Von: Alex Martelli <[e-mail]>
         # Datum: Freitag 01 Oktober 2004 04:45:34 nachmittags/abends
         # Gruppen: comp.lang.python
 
         # Michael Hohn <[e-mail]> wrote:
         # > >>> print type(builtin_check.get_global_binding('__builtins__'))
         # > <type 'dict'>
         # > >>> print type(__builtins__)
         # > <type 'module'>
         # > Is this difference in return value intentional?
 
         # Well, it's documented that '__builtins__' can be either a dictionary
         # or a module, and it's been that way for a long time. Whether it's
         # intentional (or sensible), I don't know. In any case, the idea is
         # that if you need to access the built-in namespace directly, you
         # should start with "import __builtin__" (note, no 's') which will
         # definitely give you a module. Yeah, it's somewhat confusing:-(.
 
         # These routines return a properly built module and dict as needed by
         # the rest of the code, and can also be used by extension writers to
         # generate properly initialized namespaces.
         if (user_ns is not None) or (user_module is not None):
             self.default_user_namespaces = False
         self.user_module, self.user_ns = self.prepare_user_module(user_module, user_ns)
 
         # A record of hidden variables we have added to the user namespace, so
         # we can list later only variables defined in actual interactive use.
         self.user_ns_hidden = {}
 
         # Now that FakeModule produces a real module, we've run into a nasty
         # problem: after script execution (via %run), the module where the user
         # code ran is deleted.  Now that this object is a true module (needed
         # so docetst and other tools work correctly), the Python module
         # teardown mechanism runs over it, and sets to None every variable
         # present in that module.  Top-level references to objects from the
         # script survive, because the user_ns is updated with them.  However,
         # calling functions defined in the script that use other things from
         # the script will fail, because the function's closure had references
         # to the original objects, which are now all None.  So we must protect
         # these modules from deletion by keeping a cache.
         #
         # To avoid keeping stale modules around (we only need the one from the
         # last run), we use a dict keyed with the full path to the script, so
         # only the last version of the module is held in the cache.  Note,
         # however, that we must cache the module *namespace contents* (their
         # __dict__).  Because if we try to cache the actual modules, old ones
         # (uncached) could be destroyed while still holding references (such as
         # those held by GUI objects that tend to be long-lived)>
         #
         # The %reset command will flush this cache.  See the cache_main_mod()
         # and clear_main_mod_cache() methods for details on use.
 
         # This is the cache used for 'main' namespaces
         self._main_mod_cache = {}
 
         # A table holding all the namespaces IPython deals with, so that
         # introspection facilities can search easily.
         self.ns_table = {'user_global':self.user_module.__dict__,
                          'user_local':self.user_ns,
                          'builtin':builtin_mod.__dict__
                          }
     
     @property
     def user_global_ns(self):
         return self.user_module.__dict__
 
     def prepare_user_module(self, user_module=None, user_ns=None):
         """Prepare the module and namespace in which user code will be run.
         
         When IPython is started normally, both parameters are None: a new module
         is created automatically, and its __dict__ used as the namespace.
         
         If only user_module is provided, its __dict__ is used as the namespace.
         If only user_ns is provided, a dummy module is created, and user_ns
         becomes the global namespace. If both are provided (as they may be
         when embedding), user_ns is the local namespace, and user_module
         provides the global namespace.
 
         Parameters
         ----------
         user_module : module, optional
             The current user module in which IPython is being run. If None,
             a clean module will be created.
         user_ns : dict, optional
             A namespace in which to run interactive commands.
 
         Returns
         -------
         A tuple of user_module and user_ns, each properly initialised.
         """
         if user_module is None and user_ns is not None:
             user_ns.setdefault("__name__", "__main__")
             user_module = DummyMod()
             user_module.__dict__ = user_ns
             
         if user_module is None:
             user_module = types.ModuleType("__main__",
                 doc="Automatically created module for IPython interactive environment")
         
         # We must ensure that __builtin__ (without the final 's') is always
         # available and pointing to the __builtin__ *module*.  For more details:
         # http://mail.python.org/pipermail/python-dev/2001-April/014068.html
         user_module.__dict__.setdefault('__builtin__', builtin_mod)
         user_module.__dict__.setdefault('__builtins__', builtin_mod)
         
         if user_ns is None:
             user_ns = user_module.__dict__
 
         return user_module, user_ns
 
     def init_sys_modules(self):
         # We need to insert into sys.modules something that looks like a
         # module but which accesses the IPython namespace, for shelve and
         # pickle to work interactively. Normally they rely on getting
         # everything out of __main__, but for embedding purposes each IPython
         # instance has its own private namespace, so we can't go shoving
         # everything into __main__.
 
         # note, however, that we should only do this for non-embedded
         # ipythons, which really mimic the __main__.__dict__ with their own
         # namespace.  Embedded instances, on the other hand, should not do
         # this because they need to manage the user local/global namespaces
         # only, but they live within a 'normal' __main__ (meaning, they
         # shouldn't overtake the execution environment of the script they're
         # embedded in).
 
         # This is overridden in the InteractiveShellEmbed subclass to a no-op.
         main_name = self.user_module.__name__
         sys.modules[main_name] = self.user_module
 
     def init_user_ns(self):
         """Initialize all user-visible namespaces to their minimum defaults.
 
         Certain history lists are also initialized here, as they effectively
         act as user namespaces.
 
         Notes
         -----
         All data structures here are only filled in, they are NOT reset by this
         method.  If they were not empty before, data will simply be added to
         therm.
         """
         # This function works in two parts: first we put a few things in
         # user_ns, and we sync that contents into user_ns_hidden so that these
         # initial variables aren't shown by %who.  After the sync, we add the
         # rest of what we *do* want the user to see with %who even on a new
         # session (probably nothing, so theye really only see their own stuff)
 
         # The user dict must *always* have a __builtin__ reference to the
         # Python standard __builtin__ namespace,  which must be imported.
         # This is so that certain operations in prompt evaluation can be
         # reliably executed with builtins.  Note that we can NOT use
         # __builtins__ (note the 's'),  because that can either be a dict or a
         # module, and can even mutate at runtime, depending on the context
         # (Python makes no guarantees on it).  In contrast, __builtin__ is
         # always a module object, though it must be explicitly imported.
 
         # For more details:
         # http://mail.python.org/pipermail/python-dev/2001-April/014068.html
         ns = dict()
         
         # make global variables for user access to the histories
         ns['_ih'] = self.history_manager.input_hist_parsed
         ns['_oh'] = self.history_manager.output_hist
         ns['_dh'] = self.history_manager.dir_hist
 
         ns['_sh'] = shadowns
 
         # user aliases to input and output histories.  These shouldn't show up
         # in %who, as they can have very large reprs.
         ns['In']  = self.history_manager.input_hist_parsed
         ns['Out'] = self.history_manager.output_hist
 
         # Store myself as the public api!!!
         ns['get_ipython'] = self.get_ipython
         
         ns['exit'] = self.exiter
         ns['quit'] = self.exiter
 
         # Sync what we've added so far to user_ns_hidden so these aren't seen
         # by %who
         self.user_ns_hidden.update(ns)
 
         # Anything put into ns now would show up in %who.  Think twice before
         # putting anything here, as we really want %who to show the user their
         # stuff, not our variables.
 
         # Finally, update the real user's namespace
         self.user_ns.update(ns)
     
     @property
     def all_ns_refs(self):
         """Get a list of references to all the namespace dictionaries in which
         IPython might store a user-created object.
         
         Note that this does not include the displayhook, which also caches
         objects from the output."""
         return [self.user_ns, self.user_global_ns, self.user_ns_hidden] + \
                [m.__dict__ for m in self._main_mod_cache.values()]
 
     def reset(self, new_session=True):
         """Clear all internal namespaces, and attempt to release references to
         user objects.
 
         If new_session is True, a new history session will be opened.
         """
         # Clear histories
         self.history_manager.reset(new_session)
         # Reset counter used to index all histories
         if new_session:
             self.execution_count = 1
 
         # Flush cached output items
         if self.displayhook.do_full_cache:
             self.displayhook.flush()
 
         # The main execution namespaces must be cleared very carefully,
         # skipping the deletion of the builtin-related keys, because doing so
         # would cause errors in many object's __del__ methods.
         if self.user_ns is not self.user_global_ns:
             self.user_ns.clear()
         ns = self.user_global_ns
         drop_keys = set(ns.keys())
         drop_keys.discard('__builtin__')
         drop_keys.discard('__builtins__')
         drop_keys.discard('__name__')
         for k in drop_keys:
             del ns[k]
         
         self.user_ns_hidden.clear()
         
         # Restore the user namespaces to minimal usability
         self.init_user_ns()
 
         # Restore the default and user aliases
         self.alias_manager.clear_aliases()
         self.alias_manager.init_aliases()
 
         # Flush the private list of module references kept for script
         # execution protection
         self.clear_main_mod_cache()
 
     def del_var(self, varname, by_name=False):
         """Delete a variable from the various namespaces, so that, as
         far as possible, we're not keeping any hidden references to it.
 
         Parameters
         ----------
         varname : str
             The name of the variable to delete.
         by_name : bool
             If True, delete variables with the given name in each
             namespace. If False (default), find the variable in the user
             namespace, and delete references to it.
         """
         if varname in ('__builtin__', '__builtins__'):
             raise ValueError("Refusing to delete %s" % varname)
 
         ns_refs = self.all_ns_refs
         
         if by_name:                    # Delete by name
             for ns in ns_refs:
                 try:
                     del ns[varname]
                 except KeyError:
                     pass
         else:                         # Delete by object
             try:
                 obj = self.user_ns[varname]
             except KeyError:
                 raise NameError("name '%s' is not defined" % varname)
             # Also check in output history
             ns_refs.append(self.history_manager.output_hist)
             for ns in ns_refs:
                 to_delete = [n for n, o in iteritems(ns) if o is obj]
                 for name in to_delete:
                     del ns[name]
 
             # displayhook keeps extra references, but not in a dictionary
             for name in ('_', '__', '___'):
                 if getattr(self.displayhook, name) is obj:
                     setattr(self.displayhook, name, None)
 
     def reset_selective(self, regex=None):
         """Clear selective variables from internal namespaces based on a
         specified regular expression.
 
         Parameters
         ----------
         regex : string or compiled pattern, optional
             A regular expression pattern that will be used in searching
             variable names in the users namespaces.
         """
         if regex is not None:
             try:
                 m = re.compile(regex)
             except TypeError:
                 raise TypeError('regex must be a string or compiled pattern')
             # Search for keys in each namespace that match the given regex
             # If a match is found, delete the key/value pair.
             for ns in self.all_ns_refs:
                 for var in ns:
                     if m.search(var):
                         del ns[var]
 
     def push(self, variables, interactive=True):
         """Inject a group of variables into the IPython user namespace.
 
         Parameters
         ----------
         variables : dict, str or list/tuple of str
             The variables to inject into the user's namespace.  If a dict, a
             simple update is done.  If a str, the string is assumed to have
             variable names separated by spaces.  A list/tuple of str can also
             be used to give the variable names.  If just the variable names are
             give (list/tuple/str) then the variable values looked up in the
             callers frame.
         interactive : bool
             If True (default), the variables will be listed with the ``who``
             magic.
         """
         vdict = None
 
         # We need a dict of name/value pairs to do namespace updates.
         if isinstance(variables, dict):
             vdict = variables
         elif isinstance(variables, string_types+(list, tuple)):
             if isinstance(variables, string_types):
                 vlist = variables.split()
             else:
                 vlist = variables
             vdict = {}
             cf = sys._getframe(1)
             for name in vlist:
                 try:
                     vdict[name] = eval(name, cf.f_globals, cf.f_locals)
                 except:
                     print('Could not get variable %s from %s' %
                            (name,cf.f_code.co_name))
         else:
             raise ValueError('variables must be a dict/str/list/tuple')
 
         # Propagate variables to user namespace
         self.user_ns.update(vdict)
 
         # And configure interactive visibility
         user_ns_hidden = self.user_ns_hidden
         if interactive:
             for name in vdict:
                 user_ns_hidden.pop(name, None)
         else:
             user_ns_hidden.update(vdict)
     
     def drop_by_id(self, variables):
         """Remove a dict of variables from the user namespace, if they are the
         same as the values in the dictionary.
         
         This is intended for use by extensions: variables that they've added can
         be taken back out if they are unloaded, without removing any that the
         user has overwritten.
         
         Parameters
         ----------
         variables : dict
           A dictionary mapping object names (as strings) to the objects.
         """
         for name, obj in iteritems(variables):
             if name in self.user_ns and self.user_ns[name] is obj:
                 del self.user_ns[name]
                 self.user_ns_hidden.pop(name, None)
 
     #-------------------------------------------------------------------------
     # Things related to object introspection
     #-------------------------------------------------------------------------
 
     def _ofind(self, oname, namespaces=None):
         """Find an object in the available namespaces.
 
         self._ofind(oname) -> dict with keys: found,obj,ospace,ismagic
 
         Has special code to detect magic functions.
         """
         oname = oname.strip()
         #print '1- oname: <%r>' % oname  # dbg
         if not oname.startswith(ESC_MAGIC) and \
             not oname.startswith(ESC_MAGIC2) and \
             not py3compat.isidentifier(oname, dotted=True):
             return dict(found=False)
 
         alias_ns = None
         if namespaces is None:
             # Namespaces to search in:
             # Put them in a list. The order is important so that we
             # find things in the same order that Python finds them.
             namespaces = [ ('Interactive', self.user_ns),
                            ('Interactive (global)', self.user_global_ns),
                            ('Python builtin', builtin_mod.__dict__),
                            ]
 
         # initialize results to 'null'
         found = False; obj = None;  ospace = None;  ds = None;
         ismagic = False; isalias = False; parent = None
 
         # We need to special-case 'print', which as of python2.6 registers as a
         # function but should only be treated as one if print_function was
         # loaded with a future import.  In this case, just bail.
         if (oname == 'print' and not py3compat.PY3 and not \
             (self.compile.compiler_flags & __future__.CO_FUTURE_PRINT_FUNCTION)):
             return {'found':found, 'obj':obj, 'namespace':ospace,
                     'ismagic':ismagic, 'isalias':isalias, 'parent':parent}
 
         # Look for the given name by splitting it in parts.  If the head is
         # found, then we look for all the remaining parts as members, and only
         # declare success if we can find them all.
         oname_parts = oname.split('.')
         oname_head, oname_rest = oname_parts[0],oname_parts[1:]
         for nsname,ns in namespaces:
             try:
                 obj = ns[oname_head]
             except KeyError:
                 continue
             else:
                 #print 'oname_rest:', oname_rest  # dbg
                 for part in oname_rest:
                     try:
                         parent = obj
                         obj = getattr(obj,part)
                     except:
                         # Blanket except b/c some badly implemented objects
                         # allow __getattr__ to raise exceptions other than
                         # AttributeError, which then crashes IPython.
                         break
                 else:
                     # If we finish the for loop (no break), we got all members
                     found = True
                     ospace = nsname
                     break  # namespace loop
 
         # Try to see if it's magic
         if not found:
             obj = None
             if oname.startswith(ESC_MAGIC2):
                 oname = oname.lstrip(ESC_MAGIC2)
                 obj = self.find_cell_magic(oname)
             elif oname.startswith(ESC_MAGIC):
                 oname = oname.lstrip(ESC_MAGIC)
                 obj = self.find_line_magic(oname)
             else:
                 # search without prefix, so run? will find %run?
                 obj = self.find_line_magic(oname)
                 if obj is None:
                     obj = self.find_cell_magic(oname)
             if obj is not None:
                 found = True
                 ospace = 'IPython internal'
                 ismagic = True
 
         # Last try: special-case some literals like '', [], {}, etc:
         if not found and oname_head in ["''",'""','[]','{}','()']:
             obj = eval(oname_head)
             found = True
             ospace = 'Interactive'
 
         return {'found':found, 'obj':obj, 'namespace':ospace,
                 'ismagic':ismagic, 'isalias':isalias, 'parent':parent}
 
     def _ofind_property(self, oname, info):
         """Second part of object finding, to look for property details."""
         if info.found:
             # Get the docstring of the class property if it exists.
             path = oname.split('.')
             root = '.'.join(path[:-1])
             if info.parent is not None:
                 try:
                     target = getattr(info.parent, '__class__')
                     # The object belongs to a class instance.
                     try:
                         target = getattr(target, path[-1])
                         # The class defines the object.
                         if isinstance(target, property):
                             oname = root + '.__class__.' + path[-1]
                             info = Struct(self._ofind(oname))
                     except AttributeError: pass
                 except AttributeError: pass
 
         # We return either the new info or the unmodified input if the object
         # hadn't been found
         return info
 
     def _object_find(self, oname, namespaces=None):
         """Find an object and return a struct with info about it."""
         inf = Struct(self._ofind(oname, namespaces))
         return Struct(self._ofind_property(oname, inf))
 
     def _inspect(self, meth, oname, namespaces=None, **kw):
         """Generic interface to the inspector system.
 
         This function is meant to be called by pdef, pdoc & friends."""
         info = self._object_find(oname, namespaces)
         if info.found:
             pmethod = getattr(self.inspector, meth)
             formatter = format_screen if info.ismagic else None
             if meth == 'pdoc':
                 pmethod(info.obj, oname, formatter)
             elif meth == 'pinfo':
                 pmethod(info.obj, oname, formatter, info, **kw)
             else:
                 pmethod(info.obj, oname)
         else:
             print('Object `%s` not found.' % oname)
             return 'not found'  # so callers can take other action
 
     def object_inspect(self, oname, detail_level=0):
         with self.builtin_trap:
             info = self._object_find(oname)
             if info.found:
                 return self.inspector.info(info.obj, oname, info=info,
                             detail_level=detail_level
                 )
             else:
                 return oinspect.object_info(name=oname, found=False)
 
     #-------------------------------------------------------------------------
     # Things related to history management
     #-------------------------------------------------------------------------
 
     def init_history(self):
         """Sets up the command history, and starts regular autosaves."""
         self.history_manager = HistoryManager(shell=self, parent=self)
         self.configurables.append(self.history_manager)
 
     #-------------------------------------------------------------------------
     # Things related to exception handling and tracebacks (not debugging)
     #-------------------------------------------------------------------------
 
     def init_traceback_handlers(self, custom_exceptions):
         # Syntax error handler.
         self.SyntaxTB = ultratb.SyntaxTB(color_scheme='NoColor')
 
         # The interactive one is initialized with an offset, meaning we always
         # want to remove the topmost item in the traceback, which is our own
         # internal code. Valid modes: ['Plain','Context','Verbose']
         self.InteractiveTB = ultratb.AutoFormattedTB(mode = 'Plain',
                                                      color_scheme='NoColor',
                                                      tb_offset = 1,
                                    check_cache=check_linecache_ipython)
 
         # The instance will store a pointer to the system-wide exception hook,
         # so that runtime code (such as magics) can access it.  This is because
         # during the read-eval loop, it may get temporarily overwritten.
         self.sys_excepthook = sys.excepthook
 
         # and add any custom exception handlers the user may have specified
         self.set_custom_exc(*custom_exceptions)
 
         # Set the exception mode
         self.InteractiveTB.set_mode(mode=self.xmode)
 
     def set_custom_exc(self, exc_tuple, handler):
         """set_custom_exc(exc_tuple,handler)
 
         Set a custom exception handler, which will be called if any of the
         exceptions in exc_tuple occur in the mainloop (specifically, in the
         run_code() method).
 
         Parameters
         ----------
 
         exc_tuple : tuple of exception classes
             A *tuple* of exception classes, for which to call the defined
             handler.  It is very important that you use a tuple, and NOT A
             LIST here, because of the way Python's except statement works.  If
             you only want to trap a single exception, use a singleton tuple::
 
                 exc_tuple == (MyCustomException,)
 
         handler : callable
             handler must have the following signature::
 
                 def my_handler(self, etype, value, tb, tb_offset=None):
                     ...
                     return structured_traceback
 
             Your handler must return a structured traceback (a list of strings),
             or None.
 
             This will be made into an instance method (via types.MethodType)
             of IPython itself, and it will be called if any of the exceptions
             listed in the exc_tuple are caught. If the handler is None, an
             internal basic one is used, which just prints basic info.
 
             To protect IPython from crashes, if your handler ever raises an
             exception or returns an invalid result, it will be immediately
             disabled.
 
         WARNING: by putting in your own exception handler into IPython's main
         execution loop, you run a very good chance of nasty crashes.  This
         facility should only be used if you really know what you are doing."""
 
         assert type(exc_tuple)==type(()) , \
                "The custom exceptions must be given AS A TUPLE."
 
         def dummy_handler(self,etype,value,tb,tb_offset=None):
             print('*** Simple custom exception handler ***')
             print('Exception type :',etype)
             print('Exception value:',value)
             print('Traceback      :',tb)
             #print 'Source code    :','\n'.join(self.buffer)
         
         def validate_stb(stb):
             """validate structured traceback return type
             
             return type of CustomTB *should* be a list of strings, but allow
             single strings or None, which are harmless.
             
             This function will *always* return a list of strings,
             and will raise a TypeError if stb is inappropriate.
             """
             msg = "CustomTB must return list of strings, not %r" % stb
             if stb is None:
                 return []
             elif isinstance(stb, string_types):
                 return [stb]
             elif not isinstance(stb, list):
                 raise TypeError(msg)
             # it's a list
             for line in stb:
                 # check every element
                 if not isinstance(line, string_types):
                     raise TypeError(msg)
             return stb
 
         if handler is None:
             wrapped = dummy_handler
         else:
             def wrapped(self,etype,value,tb,tb_offset=None):
                 """wrap CustomTB handler, to protect IPython from user code
                 
                 This makes it harder (but not impossible) for custom exception
                 handlers to crash IPython.
                 """
                 try:
                     stb = handler(self,etype,value,tb,tb_offset=tb_offset)
                     return validate_stb(stb)
                 except:
                     # clear custom handler immediately
                     self.set_custom_exc((), None)
                     print("Custom TB Handler failed, unregistering", file=io.stderr)
                     # show the exception in handler first
                     stb = self.InteractiveTB.structured_traceback(*sys.exc_info())
                     print(self.InteractiveTB.stb2text(stb), file=io.stdout)
                     print("The original exception:", file=io.stdout)
                     stb = self.InteractiveTB.structured_traceback(
                                             (etype,value,tb), tb_offset=tb_offset
                     )
                 return stb
 
         self.CustomTB = types.MethodType(wrapped,self)
         self.custom_exceptions = exc_tuple
 
     def excepthook(self, etype, value, tb):
       """One more defense for GUI apps that call sys.excepthook.
 
       GUI frameworks like wxPython trap exceptions and call
       sys.excepthook themselves.  I guess this is a feature that
       enables them to keep running after exceptions that would
       otherwise kill their mainloop. This is a bother for IPython
       which excepts to catch all of the program exceptions with a try:
       except: statement.
 
       Normally, IPython sets sys.excepthook to a CrashHandler instance, so if
       any app directly invokes sys.excepthook, it will look to the user like
       IPython crashed.  In order to work around this, we can disable the
       CrashHandler and replace it with this excepthook instead, which prints a
       regular traceback using our InteractiveTB.  In this fashion, apps which
       call sys.excepthook will generate a regular-looking exception from
       IPython, and the CrashHandler will only be triggered by real IPython
       crashes.
 
       This hook should be used sparingly, only in places which are not likely
       to be true IPython errors.
       """
       self.showtraceback((etype,value,tb),tb_offset=0)
 
     def _get_exc_info(self, exc_tuple=None):
         """get exc_info from a given tuple, sys.exc_info() or sys.last_type etc.
         
         Ensures sys.last_type,value,traceback hold the exc_info we found,
         from whichever source.
         
         raises ValueError if none of these contain any information
         """
         if exc_tuple is None:
             etype, value, tb = sys.exc_info()
         else:
             etype, value, tb = exc_tuple
 
         if etype is None:
             if hasattr(sys, 'last_type'):
                 etype, value, tb = sys.last_type, sys.last_value, \
                                    sys.last_traceback
         
         if etype is None:
             raise ValueError("No exception to find")
         
         # Now store the exception info in sys.last_type etc.
         # WARNING: these variables are somewhat deprecated and not
         # necessarily safe to use in a threaded environment, but tools
         # like pdb depend on their existence, so let's set them.  If we
         # find problems in the field, we'll need to revisit their use.
         sys.last_type = etype
         sys.last_value = value
         sys.last_traceback = tb
         
         return etype, value, tb
     
     def show_usage_error(self, exc):
         """Show a short message for UsageErrors
         
         These are special exceptions that shouldn't show a traceback.
         """
         self.write_err("UsageError: %s" % exc)
     
     def showtraceback(self,exc_tuple = None,filename=None,tb_offset=None,
                       exception_only=False):
         """Display the exception that just occurred.
 
         If nothing is known about the exception, this is the method which
         should be used throughout the code for presenting user tracebacks,
         rather than directly invoking the InteractiveTB object.
 
         A specific showsyntaxerror() also exists, but this method can take
         care of calling it if needed, so unless you are explicitly catching a
         SyntaxError exception, don't try to analyze the stack manually and
         simply call this method."""
 
         try:
             try:
                 etype, value, tb = self._get_exc_info(exc_tuple)
             except ValueError:
                 self.write_err('No traceback available to show.\n')
                 return
             
             if issubclass(etype, SyntaxError):
                 # Though this won't be called by syntax errors in the input
                 # line, there may be SyntaxError cases with imported code.
                 self.showsyntaxerror(filename)
             elif etype is UsageError:
                 self.show_usage_error(value)
             else:
                 if exception_only:
                     stb = ['An exception has occurred, use %tb to see '
                            'the full traceback.\n']
                     stb.extend(self.InteractiveTB.get_exception_only(etype,
                                                                      value))
                 else:
                     try:
                         # Exception classes can customise their traceback - we
                         # use this in IPython.parallel for exceptions occurring
                         # in the engines. This should return a list of strings.
                         stb = value._render_traceback_()
                     except Exception:
                         stb = self.InteractiveTB.structured_traceback(etype,
                                             value, tb, tb_offset=tb_offset)
 
                     self._showtraceback(etype, value, stb)
                     if self.call_pdb:
                         # drop into debugger
                         self.debugger(force=True)
                     return
 
                 # Actually show the traceback
                 self._showtraceback(etype, value, stb)
 
         except KeyboardInterrupt:
             self.write_err("\nKeyboardInterrupt\n")
 
     def _showtraceback(self, etype, evalue, stb):
         """Actually show a traceback.
 
         Subclasses may override this method to put the traceback on a different
         place, like a side channel.
         """
         print(self.InteractiveTB.stb2text(stb), file=io.stdout)
 
     def showsyntaxerror(self, filename=None):
         """Display the syntax error that just occurred.
 
         This doesn't display a stack trace because there isn't one.
 
         If a filename is given, it is stuffed in the exception instead
         of what was there before (because Python's parser always uses
         "<string>" when reading from a string).
         """
         etype, value, last_traceback = self._get_exc_info()
 
         if filename and issubclass(etype, SyntaxError):
             try:
                 value.filename = filename
             except:
                 # Not the format we expect; leave it alone
                 pass
         
         stb = self.SyntaxTB.structured_traceback(etype, value, [])
         self._showtraceback(etype, value, stb)
 
     # This is overridden in TerminalInteractiveShell to show a message about
     # the %paste magic.
     def showindentationerror(self):
         """Called by run_cell when there's an IndentationError in code entered
         at the prompt.
 
         This is overridden in TerminalInteractiveShell to show a message about
         the %paste magic."""
         self.showsyntaxerror()
 
     #-------------------------------------------------------------------------
     # Things related to readline
     #-------------------------------------------------------------------------
 
     def init_readline(self):
         """Command history completion/saving/reloading."""
 
         if self.readline_use:
             import IPython.utils.rlineimpl as readline
 
         self.rl_next_input = None
         self.rl_do_indent = False
 
         if not self.readline_use or not readline.have_readline:
             self.has_readline = False
             self.readline = None
             # Set a number of methods that depend on readline to be no-op
             self.readline_no_record = no_op_context
             self.set_readline_completer = no_op
             self.set_custom_completer = no_op
             if self.readline_use:
                 warn('Readline services not available or not loaded.')
         else:
             self.has_readline = True
             self.readline = readline
             sys.modules['readline'] = readline
 
             # Platform-specific configuration
             if os.name == 'nt':
                 # FIXME - check with Frederick to see if we can harmonize
                 # naming conventions with pyreadline to avoid this
                 # platform-dependent check
                 self.readline_startup_hook = readline.set_pre_input_hook
             else:
                 self.readline_startup_hook = readline.set_startup_hook
 
             # Load user's initrc file (readline config)
             # Or if libedit is used, load editrc.
             inputrc_name = os.environ.get('INPUTRC')
             if inputrc_name is None:
                 inputrc_name = '.inputrc'
                 if readline.uses_libedit:
                     inputrc_name = '.editrc'
                 inputrc_name = os.path.join(self.home_dir, inputrc_name)
             if os.path.isfile(inputrc_name):
                 try:
                     readline.read_init_file(inputrc_name)
                 except:
                     warn('Problems reading readline initialization file <%s>'
                          % inputrc_name)
 
             # Configure readline according to user's prefs
             # This is only done if GNU readline is being used.  If libedit
             # is being used (as on Leopard) the readline config is
             # not run as the syntax for libedit is different.
             if not readline.uses_libedit:
                 for rlcommand in self.readline_parse_and_bind:
                     #print "loading rl:",rlcommand  # dbg
                     readline.parse_and_bind(rlcommand)
 
             # Remove some chars from the delimiters list.  If we encounter
             # unicode chars, discard them.
             delims = readline.get_completer_delims()
             if not py3compat.PY3:
                 delims = delims.encode("ascii", "ignore")
             for d in self.readline_remove_delims:
                 delims = delims.replace(d, "")
             delims = delims.replace(ESC_MAGIC, '')
             readline.set_completer_delims(delims)
             # Store these so we can restore them if something like rpy2 modifies
             # them.
             self.readline_delims = delims
             # otherwise we end up with a monster history after a while:
             readline.set_history_length(self.history_length)
 
             self.refill_readline_hist()
             self.readline_no_record = ReadlineNoRecord(self)
 
         # Configure auto-indent for all platforms
         self.set_autoindent(self.autoindent)
 
     def refill_readline_hist(self):
         # Load the last 1000 lines from history
         self.readline.clear_history()
         stdin_encoding = sys.stdin.encoding or "utf-8"
         last_cell = u""
         for _, _, cell in self.history_manager.get_tail(1000,
                                                         include_latest=True):
             # Ignore blank lines and consecutive duplicates
             cell = cell.rstrip()
             if cell and (cell != last_cell):
                 try:
                     if self.multiline_history:
                           self.readline.add_history(py3compat.unicode_to_str(cell,
                                                                     stdin_encoding))
                     else:
                         for line in cell.splitlines():
                             self.readline.add_history(py3compat.unicode_to_str(line,
                                                                     stdin_encoding))
                     last_cell = cell
                 
                 except TypeError:
                     # The history DB can get corrupted so it returns strings
                     # containing null bytes, which readline objects to.
                     continue
 
     @skip_doctest
     def set_next_input(self, s):
         """ Sets the 'default' input string for the next command line.
 
         Requires readline.
 
         Example::
 
             In [1]: _ip.set_next_input("Hello Word")
             In [2]: Hello Word_  # cursor is here
         """
         self.rl_next_input = py3compat.cast_bytes_py2(s)
 
     # Maybe move this to the terminal subclass?
     def pre_readline(self):
         """readline hook to be used at the start of each line.
 
         Currently it handles auto-indent only."""
 
         if self.rl_do_indent:
             self.readline.insert_text(self._indent_current_str())
         if self.rl_next_input is not None:
             self.readline.insert_text(self.rl_next_input)
             self.rl_next_input = None
 
     def _indent_current_str(self):
         """return the current level of indentation as a string"""
         return self.input_splitter.indent_spaces * ' '
 
     #-------------------------------------------------------------------------
     # Things related to text completion
     #-------------------------------------------------------------------------
 
     def init_completer(self):
         """Initialize the completion machinery.
 
         This creates completion machinery that can be used by client code,
         either interactively in-process (typically triggered by the readline
         library), programatically (such as in test suites) or out-of-prcess
         (typically over the network by remote frontends).
         """
         from IPython.core.completer import IPCompleter
         from IPython.core.completerlib import (module_completer,
                 magic_run_completer, cd_completer, reset_completer)
 
         self.Completer = IPCompleter(shell=self,
                                      namespace=self.user_ns,
                                      global_namespace=self.user_global_ns,
                                      use_readline=self.has_readline,
                                      parent=self,
                                      )
         self.configurables.append(self.Completer)
 
         # Add custom completers to the basic ones built into IPCompleter
         sdisp = self.strdispatchers.get('complete_command', StrDispatch())
         self.strdispatchers['complete_command'] = sdisp
         self.Completer.custom_completers = sdisp
 
         self.set_hook('complete_command', module_completer, str_key = 'import')
         self.set_hook('complete_command', module_completer, str_key = 'from')
         self.set_hook('complete_command', magic_run_completer, str_key = '%run')
         self.set_hook('complete_command', cd_completer, str_key = '%cd')
         self.set_hook('complete_command', reset_completer, str_key = '%reset')
 
         # Only configure readline if we truly are using readline.  IPython can
         # do tab-completion over the network, in GUIs, etc, where readline
         # itself may be absent
         if self.has_readline:
             self.set_readline_completer()
 
     def complete(self, text, line=None, cursor_pos=None):
         """Return the completed text and a list of completions.
 
         Parameters
         ----------
 
            text : string
              A string of text to be completed on.  It can be given as empty and
              instead a line/position pair are given.  In this case, the
              completer itself will split the line like readline does.
 
            line : string, optional
              The complete line that text is part of.
 
            cursor_pos : int, optional
              The position of the cursor on the input line.
 
         Returns
         -------
           text : string
             The actual text that was completed.
 
           matches : list
             A sorted list with all possible completions.
 
         The optional arguments allow the completion to take more context into
         account, and are part of the low-level completion API.
 
         This is a wrapper around the completion mechanism, similar to what
         readline does at the command line when the TAB key is hit.  By
         exposing it as a method, it can be used by other non-readline
         environments (such as GUIs) for text completion.
 
         Simple usage example:
 
         In [1]: x = 'hello'
 
         In [2]: _ip.complete('x.l')
         Out[2]: ('x.l', ['x.ljust', 'x.lower', 'x.lstrip'])
         """
 
         # Inject names into __builtin__ so we can complete on the added names.
         with self.builtin_trap:
             return self.Completer.complete(text, line, cursor_pos)
 
     def set_custom_completer(self, completer, pos=0):
         """Adds a new custom completer function.
 
         The position argument (defaults to 0) is the index in the completers
         list where you want the completer to be inserted."""
 
         newcomp = types.MethodType(completer,self.Completer)
         self.Completer.matchers.insert(pos,newcomp)
 
     def set_readline_completer(self):
         """Reset readline's completer to be our own."""
         self.readline.set_completer(self.Completer.rlcomplete)
 
     def set_completer_frame(self, frame=None):
         """Set the frame of the completer."""
         if frame:
             self.Completer.namespace = frame.f_locals
             self.Completer.global_namespace = frame.f_globals
         else:
             self.Completer.namespace = self.user_ns
             self.Completer.global_namespace = self.user_global_ns
 
     #-------------------------------------------------------------------------
     # Things related to magics
     #-------------------------------------------------------------------------
 
     def init_magics(self):
         from IPython.core import magics as m
         self.magics_manager = magic.MagicsManager(shell=self,
                                    parent=self,
                                    user_magics=m.UserMagics(self))
         self.configurables.append(self.magics_manager)
 
         # Expose as public API from the magics manager
         self.register_magics = self.magics_manager.register
         self.define_magic = self.magics_manager.define_magic
 
         self.register_magics(m.AutoMagics, m.BasicMagics, m.CodeMagics,
             m.ConfigMagics, m.DeprecatedMagics, m.DisplayMagics, m.ExecutionMagics,
             m.ExtensionMagics, m.HistoryMagics, m.LoggingMagics,
             m.NamespaceMagics, m.OSMagics, m.PylabMagics, m.ScriptMagics,
         )
 
         # Register Magic Aliases
         mman = self.magics_manager
         # FIXME: magic aliases should be defined by the Magics classes
         # or in MagicsManager, not here
         mman.register_alias('ed', 'edit')
         mman.register_alias('hist', 'history')
         mman.register_alias('rep', 'recall')
         mman.register_alias('SVG', 'svg', 'cell')
         mman.register_alias('HTML', 'html', 'cell')
         mman.register_alias('file', 'writefile', 'cell')
 
         # FIXME: Move the color initialization to the DisplayHook, which
         # should be split into a prompt manager and displayhook. We probably
         # even need a centralize colors management object.
         self.magic('colors %s' % self.colors)
     
     # Defined here so that it's included in the documentation
     @functools.wraps(magic.MagicsManager.register_function)
     def register_magic_function(self, func, magic_kind='line', magic_name=None):
         self.magics_manager.register_function(func, 
                                   magic_kind=magic_kind, magic_name=magic_name)
 
     def run_line_magic(self, magic_name, line):
         """Execute the given line magic.
 
         Parameters
         ----------
         magic_name : str
           Name of the desired magic function, without '%' prefix.
 
         line : str
           The rest of the input line as a single string.
         """
         fn = self.find_line_magic(magic_name)
         if fn is None:
             cm = self.find_cell_magic(magic_name)
             etpl = "Line magic function `%%%s` not found%s."
             extra = '' if cm is None else (' (But cell magic `%%%%%s` exists, '
                                     'did you mean that instead?)' % magic_name )
             error(etpl % (magic_name, extra))
         else:
             # Note: this is the distance in the stack to the user's frame.
             # This will need to be updated if the internal calling logic gets
             # refactored, or else we'll be expanding the wrong variables.
             stack_depth = 2
             magic_arg_s = self.var_expand(line, stack_depth)
             # Put magic args in a list so we can call with f(*a) syntax
             args = [magic_arg_s]
             kwargs = {}
             # Grab local namespace if we need it:
             if getattr(fn, "needs_local_scope", False):
                 kwargs['local_ns'] = sys._getframe(stack_depth).f_locals
             with self.builtin_trap:
                 result = fn(*args,**kwargs)
             return result
 
     def run_cell_magic(self, magic_name, line, cell):
         """Execute the given cell magic.
         
         Parameters
         ----------
         magic_name : str
           Name of the desired magic function, without '%' prefix.
 
         line : str
           The rest of the first input line as a single string.
 
         cell : str
           The body of the cell as a (possibly multiline) string.
         """
         fn = self.find_cell_magic(magic_name)
         if fn is None:
             lm = self.find_line_magic(magic_name)
             etpl = "Cell magic `%%{0}` not found{1}."
             extra = '' if lm is None else (' (But line magic `%{0}` exists, '
                             'did you mean that instead?)'.format(magic_name))
             error(etpl.format(magic_name, extra))
         elif cell == '':
             message = '%%{0} is a cell magic, but the cell body is empty.'.format(magic_name)
             if self.find_line_magic(magic_name) is not None:
                 message += ' Did you mean the line magic %{0} (single %)?'.format(magic_name)
             raise UsageError(message)
         else:
             # Note: this is the distance in the stack to the user's frame.
             # This will need to be updated if the internal calling logic gets
             # refactored, or else we'll be expanding the wrong variables.
             stack_depth = 2
             magic_arg_s = self.var_expand(line, stack_depth)
             with self.builtin_trap:
                 result = fn(magic_arg_s, cell)
             return result
 
     def find_line_magic(self, magic_name):
         """Find and return a line magic by name.
 
         Returns None if the magic isn't found."""
         return self.magics_manager.magics['line'].get(magic_name)
 
     def find_cell_magic(self, magic_name):
         """Find and return a cell magic by name.
 
         Returns None if the magic isn't found."""
         return self.magics_manager.magics['cell'].get(magic_name)
 
     def find_magic(self, magic_name, magic_kind='line'):
         """Find and return a magic of the given type by name.
 
         Returns None if the magic isn't found."""
         return self.magics_manager.magics[magic_kind].get(magic_name)
 
     def magic(self, arg_s):
         """DEPRECATED. Use run_line_magic() instead.
 
         Call a magic function by name.
 
         Input: a string containing the name of the magic function to call and
         any additional arguments to be passed to the magic.
 
         magic('name -opt foo bar') is equivalent to typing at the ipython
         prompt:
 
         In[1]: %name -opt foo bar
 
         To call a magic without arguments, simply use magic('name').
 
         This provides a proper Python function to call IPython's magics in any
         valid Python code you can type at the interpreter, including loops and
         compound statements.
         """
         # TODO: should we issue a loud deprecation warning here?
         magic_name, _, magic_arg_s = arg_s.partition(' ')
         magic_name = magic_name.lstrip(prefilter.ESC_MAGIC)
         return self.run_line_magic(magic_name, magic_arg_s)
 
     #-------------------------------------------------------------------------
     # Things related to macros
     #-------------------------------------------------------------------------
 
     def define_macro(self, name, themacro):
         """Define a new macro
 
         Parameters
         ----------
         name : str
             The name of the macro.
         themacro : str or Macro
             The action to do upon invoking the macro.  If a string, a new
             Macro object is created by passing the string to it.
         """
 
         from IPython.core import macro
 
         if isinstance(themacro, string_types):
             themacro = macro.Macro(themacro)
         if not isinstance(themacro, macro.Macro):
             raise ValueError('A macro must be a string or a Macro instance.')
         self.user_ns[name] = themacro
 
     #-------------------------------------------------------------------------
     # Things related to the running of system commands
     #-------------------------------------------------------------------------
 
     def system_piped(self, cmd):
         """Call the given cmd in a subprocess, piping stdout/err
 
         Parameters
         ----------
         cmd : str
           Command to execute (can not end in '&', as background processes are
           not supported.  Should not be a command that expects input
           other than simple text.
         """
         if cmd.rstrip().endswith('&'):
             # this is *far* from a rigorous test
             # We do not support backgrounding processes because we either use
             # pexpect or pipes to read from.  Users can always just call
             # os.system() or use ip.system=ip.system_raw
             # if they really want a background process.
             raise OSError("Background processes not supported.")
 
         # we explicitly do NOT return the subprocess status code, because
         # a non-None value would trigger :func:`sys.displayhook` calls.
         # Instead, we store the exit_code in user_ns.
         self.user_ns['_exit_code'] = system(self.var_expand(cmd, depth=1))
 
     def system_raw(self, cmd):
         """Call the given cmd in a subprocess using os.system on Windows or
         subprocess.call using the system shell on other platforms.
 
         Parameters
         ----------
         cmd : str
           Command to execute.
         """
         cmd = self.var_expand(cmd, depth=1)
         # protect os.system from UNC paths on Windows, which it can't handle:
         if sys.platform == 'win32':
             from IPython.utils._process_win32 import AvoidUNCPath
             with AvoidUNCPath() as path:
                 if path is not None:
                     cmd = '"pushd %s &&"%s' % (path, cmd)
                 cmd = py3compat.unicode_to_str(cmd)
                 ec = os.system(cmd)
         else:
             cmd = py3compat.unicode_to_str(cmd)
             # Call the cmd using the OS shell, instead of the default /bin/sh, if set.
             ec = subprocess.call(cmd, shell=True, executable=os.environ.get('SHELL', None))
             # exit code is positive for program failure, or negative for
             # terminating signal number.
         
         # We explicitly do NOT return the subprocess status code, because
         # a non-None value would trigger :func:`sys.displayhook` calls.
         # Instead, we store the exit_code in user_ns.
         self.user_ns['_exit_code'] = ec
 
     # use piped system by default, because it is better behaved
     system = system_piped
 
     def getoutput(self, cmd, split=True, depth=0):
         """Get output (possibly including stderr) from a subprocess.
 
         Parameters
         ----------
         cmd : str
           Command to execute (can not end in '&', as background processes are
           not supported.
         split : bool, optional
           If True, split the output into an IPython SList.  Otherwise, an
           IPython LSString is returned.  These are objects similar to normal
           lists and strings, with a few convenience attributes for easier
           manipulation of line-based output.  You can use '?' on them for
           details.
         depth : int, optional
           How many frames above the caller are the local variables which should
           be expanded in the command string? The default (0) assumes that the
           expansion variables are in the stack frame calling this function.
         """
         if cmd.rstrip().endswith('&'):
             # this is *far* from a rigorous test
             raise OSError("Background processes not supported.")
         out = getoutput(self.var_expand(cmd, depth=depth+1))
         if split:
             out = SList(out.splitlines())
         else:
             out = LSString(out)
         return out
 
     #-------------------------------------------------------------------------
     # Things related to aliases
     #-------------------------------------------------------------------------
 
     def init_alias(self):
         self.alias_manager = AliasManager(shell=self, parent=self)
         self.configurables.append(self.alias_manager)
 
     #-------------------------------------------------------------------------
     # Things related to extensions
     #-------------------------------------------------------------------------
 
     def init_extension_manager(self):
         self.extension_manager = ExtensionManager(shell=self, parent=self)
         self.configurables.append(self.extension_manager)
 
     #-------------------------------------------------------------------------
     # Things related to payloads
     #-------------------------------------------------------------------------
 
     def init_payload(self):
         self.payload_manager = PayloadManager(parent=self)
         self.configurables.append(self.payload_manager)
     
     #-------------------------------------------------------------------------
     # Things related to widgets
     #-------------------------------------------------------------------------
     
     def init_comms(self):
         # not implemented in the base class
         pass
     
     #-------------------------------------------------------------------------
     # Things related to the prefilter
     #-------------------------------------------------------------------------
 
     def init_prefilter(self):
         self.prefilter_manager = PrefilterManager(shell=self, parent=self)
         self.configurables.append(self.prefilter_manager)
         # Ultimately this will be refactored in the new interpreter code, but
         # for now, we should expose the main prefilter method (there's legacy
         # code out there that may rely on this).
         self.prefilter = self.prefilter_manager.prefilter_lines
 
     def auto_rewrite_input(self, cmd):
         """Print to the screen the rewritten form of the user's command.
 
         This shows visual feedback by rewriting input lines that cause
         automatic calling to kick in, like::
 
           /f x
 
         into::
 
           ------> f(x)
 
         after the user's input prompt.  This helps the user understand that the
         input line was transformed automatically by IPython.
         """
         if not self.show_rewritten_input:
             return
         
         rw = self.prompt_manager.render('rewrite') + cmd
 
         try:
             # plain ascii works better w/ pyreadline, on some machines, so
             # we use it and only print uncolored rewrite if we have unicode
             rw = str(rw)
             print(rw, file=io.stdout)
         except UnicodeEncodeError:
             print("------> " + cmd)
 
     #-------------------------------------------------------------------------
     # Things related to extracting values/expressions from kernel and user_ns
     #-------------------------------------------------------------------------
 
     def _user_obj_error(self):
         """return simple exception dict
         
         for use in user_variables / expressions
         """
         
         etype, evalue, tb = self._get_exc_info()
         stb = self.InteractiveTB.get_exception_only(etype, evalue)
         
         exc_info = {
             u'status' : 'error',
             u'traceback' : stb,
             u'ename' : unicode_type(etype.__name__),
             u'evalue' : py3compat.safe_unicode(evalue),
         }
 
         return exc_info
     
     def _format_user_obj(self, obj):
         """format a user object to display dict
         
         for use in user_expressions / variables
         """
         
         data, md = self.display_formatter.format(obj)
         value = {
             'status' : 'ok',
             'data' : data,
             'metadata' : md,
         }
         return value
     
     def user_variables(self, names):
         """Get a list of variable names from the user's namespace.
 
         Parameters
         ----------
         names : list of strings
           A list of names of variables to be read from the user namespace.
 
         Returns
         -------
         A dict, keyed by the input names and with the rich mime-type repr(s) of each value.
         Each element will be a sub-dict of the same form as a display_data message.
         """
         out = {}
         user_ns = self.user_ns
         
         for varname in names:
             try:
                 value = self._format_user_obj(user_ns[varname])
             except:
                 value = self._user_obj_error()
             out[varname] = value
         return out
 
     def user_expressions(self, expressions):
         """Evaluate a dict of expressions in the user's namespace.
 
         Parameters
         ----------
         expressions : dict
           A dict with string keys and string values.  The expression values
           should be valid Python expressions, each of which will be evaluated
           in the user namespace.
 
         Returns
         -------
         A dict, keyed like the input expressions dict, with the rich mime-typed
         display_data of each value.
         """
         out = {}
         user_ns = self.user_ns
         global_ns = self.user_global_ns
         
         for key, expr in iteritems(expressions):
             try:
                 value = self._format_user_obj(eval(expr, global_ns, user_ns))
             except:
                 value = self._user_obj_error()
             out[key] = value
         return out
 
     #-------------------------------------------------------------------------
     # Things related to the running of code
     #-------------------------------------------------------------------------
 
     def ex(self, cmd):
         """Execute a normal python statement in user namespace."""
         with self.builtin_trap:
             exec(cmd, self.user_global_ns, self.user_ns)
 
     def ev(self, expr):
         """Evaluate python expression expr in user namespace.
 
         Returns the result of evaluation
         """
         with self.builtin_trap:
             return eval(expr, self.user_global_ns, self.user_ns)
 
     def safe_execfile(self, fname, *where, **kw):
         """A safe version of the builtin execfile().
 
         This version will never throw an exception, but instead print
         helpful error messages to the screen.  This only works on pure
         Python files with the .py extension.
 
         Parameters
         ----------
         fname : string
             The name of the file to be executed.
         where : tuple
             One or two namespaces, passed to execfile() as (globals,locals).
             If only one is given, it is passed as both.
         exit_ignore : bool (False)
             If True, then silence SystemExit for non-zero status (it is always
             silenced for zero status, as it is so common).
         raise_exceptions : bool (False)
             If True raise exceptions everywhere. Meant for testing.
 
         """
         kw.setdefault('exit_ignore', False)
         kw.setdefault('raise_exceptions', False)
 
         fname = os.path.abspath(os.path.expanduser(fname))
 
         # Make sure we can open the file
         try:
             with open(fname) as thefile:
                 pass
         except:
             warn('Could not open file <%s> for safe execution.' % fname)
             return
 
         # Find things also in current directory.  This is needed to mimic the
         # behavior of running a script from the system command line, where
         # Python inserts the script's directory into sys.path
         dname = os.path.dirname(fname)
 
         with prepended_to_syspath(dname):
             try:
                 py3compat.execfile(fname,*where)
             except SystemExit as status:
                 # If the call was made with 0 or None exit status (sys.exit(0)
                 # or sys.exit() ), don't bother showing a traceback, as both of
                 # these are considered normal by the OS:
                 # > python -c'import sys;sys.exit(0)'; echo $?
                 # 0
                 # > python -c'import sys;sys.exit()'; echo $?
                 # 0
                 # For other exit status, we show the exception unless
                 # explicitly silenced, but only in short form.
                 if kw['raise_exceptions']:
                     raise
                 if status.code and not kw['exit_ignore']:
                     self.showtraceback(exception_only=True)
             except:
                 if kw['raise_exceptions']:
                     raise
                 # tb offset is 2 because we wrap execfile
                 self.showtraceback(tb_offset=2)
 
     def safe_execfile_ipy(self, fname):
         """Like safe_execfile, but for .ipy or .ipynb files with IPython syntax.
 
         Parameters
         ----------
         fname : str
             The name of the file to execute.  The filename must have a
             .ipy or .ipynb extension.
         """
         fname = os.path.abspath(os.path.expanduser(fname))
 
         # Make sure we can open the file
         try:
             with open(fname) as thefile:
                 pass
         except:
             warn('Could not open file <%s> for safe execution.' % fname)
             return
 
         # Find things also in current directory.  This is needed to mimic the
         # behavior of running a script from the system command line, where
         # Python inserts the script's directory into sys.path
         dname = os.path.dirname(fname)
         
         def get_cells():
             """generator for sequence of code blocks to run"""
             if fname.endswith('.ipynb'):
                 from IPython.nbformat import current
                 with open(fname) as f:
                     nb = current.read(f, 'json')
                     if not nb.worksheets:
                         return
                     for cell in nb.worksheets[0].cells:
                         if cell.cell_type == 'code':
                             yield cell.input
             else:
                 with open(fname) as f:
                     yield f.read()
 
         with prepended_to_syspath(dname):
             try:
                 for cell in get_cells():
                     # self.run_cell currently captures all exceptions
                     # raised in user code.  It would be nice if there were
                     # versions of run_cell that did raise, so
                     # we could catch the errors.
                     self.run_cell(cell, store_history=False, shell_futures=False)
             except:
                 self.showtraceback()
                 warn('Unknown failure executing file: <%s>' % fname)
 
     def safe_run_module(self, mod_name, where):
         """A safe version of runpy.run_module().
 
         This version will never throw an exception, but instead print
         helpful error messages to the screen.
 
         `SystemExit` exceptions with status code 0 or None are ignored.
 
         Parameters
         ----------
         mod_name : string
             The name of the module to be executed.
         where : dict
             The globals namespace.
         """
         try:
             try:
                 where.update(
                     runpy.run_module(str(mod_name), run_name="__main__",
                                      alter_sys=True)
                     )
             except SystemExit as status:
                 if status.code:
                     raise
         except:
             self.showtraceback()
             warn('Unknown failure executing module: <%s>' % mod_name)
 
     def _run_cached_cell_magic(self, magic_name, line):
         """Special method to call a cell magic with the data stored in self.
         """
         cell = self._current_cell_magic_body
         self._current_cell_magic_body = None
         return self.run_cell_magic(magic_name, line, cell)
 
     def run_cell(self, raw_cell, store_history=False, silent=False, shell_futures=True):
         """Run a complete IPython cell.
 
         Parameters
         ----------
         raw_cell : str
           The code (including IPython code such as %magic functions) to run.
         store_history : bool
           If True, the raw and translated cell will be stored in IPython's
           history. For user code calling back into IPython's machinery, this
           should be set to False.
         silent : bool
           If True, avoid side-effects, such as implicit displayhooks and
           and logging.  silent=True forces store_history=False.
         shell_futures : bool
           If True, the code will share future statements with the interactive
           shell. It will both be affected by previous __future__ imports, and
           any __future__ imports in the code will affect the shell. If False,
           __future__ imports are not shared in either direction.
         """
         if (not raw_cell) or raw_cell.isspace():
             return
         
         if silent:
             store_history = False
 
         self.events.trigger('pre_execute')
         if not silent:
             self.events.trigger('pre_run_cell')
 
         # If any of our input transformation (input_transformer_manager or
         # prefilter_manager) raises an exception, we store it in this variable
         # so that we can display the error after logging the input and storing
         # it in the history.
         preprocessing_exc_tuple = None
         try:
             # Static input transformations
             cell = self.input_transformer_manager.transform_cell(raw_cell)
         except SyntaxError:
             preprocessing_exc_tuple = sys.exc_info()
             cell = raw_cell  # cell has to exist so it can be stored/logged
         else:
             if len(cell.splitlines()) == 1:
                 # Dynamic transformations - only applied for single line commands
                 with self.builtin_trap:
                     try:
                         # use prefilter_lines to handle trailing newlines
                         # restore trailing newline for ast.parse
                         cell = self.prefilter_manager.prefilter_lines(cell) + '\n'
                     except Exception:
                         # don't allow prefilter errors to crash IPython
                         preprocessing_exc_tuple = sys.exc_info()
 
         # Store raw and processed history
         if store_history:
             self.history_manager.store_inputs(self.execution_count,
                                               cell, raw_cell)
         if not silent:
             self.logger.log(cell, raw_cell)
 
         # Display the exception if input processing failed.
         if preprocessing_exc_tuple is not None:
             self.showtraceback(preprocessing_exc_tuple)
             if store_history:
                 self.execution_count += 1
             return
 
         # Our own compiler remembers the __future__ environment. If we want to
         # run code with a separate __future__ environment, use the default
         # compiler
         compiler = self.compile if shell_futures else CachingCompiler()
 
         with self.builtin_trap:
             cell_name = self.compile.cache(cell, self.execution_count)
 
             with self.display_trap:
                 # Compile to bytecode
                 try:
                     code_ast = compiler.ast_parse(cell, filename=cell_name)
                 except IndentationError:
                     self.showindentationerror()
                     if store_history:
                         self.execution_count += 1
                     return None
                 except (OverflowError, SyntaxError, ValueError, TypeError,
                         MemoryError):
                     self.showsyntaxerror()
                     if store_history:
                         self.execution_count += 1
                     return None
 
                 # Apply AST transformations
                 code_ast = self.transform_ast(code_ast)
 
                 # Execute the user code
                 interactivity = "none" if silent else self.ast_node_interactivity
                 self.run_ast_nodes(code_ast.body, cell_name,
                                    interactivity=interactivity, compiler=compiler)
                 
                 self.events.trigger('post_execute')
                 if not silent:
                     self.events.trigger('post_run_cell')
 
         if store_history:
             # Write output to the database. Does nothing unless
             # history output logging is enabled.
             self.history_manager.store_output(self.execution_count)
             # Each cell is a *single* input, regardless of how many lines it has
             self.execution_count += 1
     
     def transform_ast(self, node):
         """Apply the AST transformations from self.ast_transformers
         
         Parameters
         ----------
         node : ast.Node
           The root node to be transformed. Typically called with the ast.Module
           produced by parsing user input.
         
         Returns
         -------
         An ast.Node corresponding to the node it was called with. Note that it
         may also modify the passed object, so don't rely on references to the
         original AST.
         """
         for transformer in self.ast_transformers:
             try:
                 node = transformer.visit(node)
             except Exception:
                 warn("AST transformer %r threw an error. It will be unregistered." % transformer)
                 self.ast_transformers.remove(transformer)
         
         if self.ast_transformers:
             ast.fix_missing_locations(node)
         return node
                 
 
     def run_ast_nodes(self, nodelist, cell_name, interactivity='last_expr',
                         compiler=compile):
         """Run a sequence of AST nodes. The execution mode depends on the
         interactivity parameter.
 
         Parameters
         ----------
         nodelist : list
           A sequence of AST nodes to run.
         cell_name : str
           Will be passed to the compiler as the filename of the cell. Typically
           the value returned by ip.compile.cache(cell).
         interactivity : str
           'all', 'last', 'last_expr' or 'none', specifying which nodes should be
           run interactively (displaying output from expressions). 'last_expr'
           will run the last node interactively only if it is an expression (i.e.
           expressions in loops or other blocks are not displayed. Other values
           for this parameter will raise a ValueError.
         compiler : callable
           A function with the same interface as the built-in compile(), to turn
           the AST nodes into code objects. Default is the built-in compile().
         """
         if not nodelist:
             return
 
         if interactivity == 'last_expr':
             if isinstance(nodelist[-1], ast.Expr):
                 interactivity = "last"
             else:
                 interactivity = "none"
 
         if interactivity == 'none':
             to_run_exec, to_run_interactive = nodelist, []
         elif interactivity == 'last':
             to_run_exec, to_run_interactive = nodelist[:-1], nodelist[-1:]
         elif interactivity == 'all':
             to_run_exec, to_run_interactive = [], nodelist
         else:
             raise ValueError("Interactivity was %r" % interactivity)
 
         exec_count = self.execution_count
 
         try:
             for i, node in enumerate(to_run_exec):
                 mod = ast.Module([node])
                 code = compiler(mod, cell_name, "exec")
                 if self.run_code(code):
                     return True
 
             for i, node in enumerate(to_run_interactive):
                 mod = ast.Interactive([node])
                 code = compiler(mod, cell_name, "single")
                 if self.run_code(code):
                     return True
 
             # Flush softspace
             if softspace(sys.stdout, 0):
                 print()
 
         except:
             # It's possible to have exceptions raised here, typically by
             # compilation of odd code (such as a naked 'return' outside a
             # function) that did parse but isn't valid. Typically the exception
             # is a SyntaxError, but it's safest just to catch anything and show
             # the user a traceback.
 
             # We do only one try/except outside the loop to minimize the impact
             # on runtime, and also because if any node in the node list is
             # broken, we should stop execution completely.
             self.showtraceback()
 
         return False
 
     def run_code(self, code_obj):
         """Execute a code object.
 
         When an exception occurs, self.showtraceback() is called to display a
         traceback.
 
         Parameters
         ----------
         code_obj : code object
           A compiled code object, to be executed
 
         Returns
         -------
         False : successful execution.
         True : an error occurred.
         """
 
         # Set our own excepthook in case the user code tries to call it
         # directly, so that the IPython crash handler doesn't get triggered
         old_excepthook,sys.excepthook = sys.excepthook, self.excepthook
 
         # we save the original sys.excepthook in the instance, in case config
         # code (such as magics) needs access to it.
         self.sys_excepthook = old_excepthook
         outflag = 1  # happens in more places, so it's easier as default
         try:
             try:
                 self.hooks.pre_run_code_hook()
                 #rprint('Running code', repr(code_obj)) # dbg
                 exec(code_obj, self.user_global_ns, self.user_ns)
             finally:
                 # Reset our crash handler in place
                 sys.excepthook = old_excepthook
         except SystemExit:
             self.showtraceback(exception_only=True)
             warn("To exit: use 'exit', 'quit', or Ctrl-D.", level=1)
         except self.custom_exceptions:
             etype,value,tb = sys.exc_info()
             self.CustomTB(etype,value,tb)
         except:
             self.showtraceback()
         else:
             outflag = 0
         return outflag
 
     # For backwards compatibility
     runcode = run_code
 
     #-------------------------------------------------------------------------
     # Things related to GUI support and pylab
     #-------------------------------------------------------------------------
 
     def enable_gui(self, gui=None):
         raise NotImplementedError('Implement enable_gui in a subclass')
     
     def enable_matplotlib(self, gui=None):
         """Enable interactive matplotlib and inline figure support.
         
         This takes the following steps:
         
         1. select the appropriate eventloop and matplotlib backend
         2. set up matplotlib for interactive use with that backend
         3. configure formatters for inline figure display
         4. enable the selected gui eventloop
         
         Parameters
         ----------
         gui : optional, string
           If given, dictates the choice of matplotlib GUI backend to use
           (should be one of IPython's supported backends, 'qt', 'osx', 'tk',
           'gtk', 'wx' or 'inline'), otherwise we use the default chosen by
           matplotlib (as dictated by the matplotlib build-time options plus the
           user's matplotlibrc configuration file).  Note that not all backends
           make sense in all contexts, for example a terminal ipython can't
           display figures inline.
         """
         from IPython.core import pylabtools as pt
         gui, backend = pt.find_gui_and_backend(gui, self.pylab_gui_select)
     
         if gui != 'inline':
             # If we have our first gui selection, store it
             if self.pylab_gui_select is None:
                 self.pylab_gui_select = gui
             # Otherwise if they are different
             elif gui != self.pylab_gui_select:
                 print ('Warning: Cannot change to a different GUI toolkit: %s.'
                         ' Using %s instead.' % (gui, self.pylab_gui_select))
                 gui, backend = pt.find_gui_and_backend(self.pylab_gui_select)
         
         pt.activate_matplotlib(backend)
         pt.configure_inline_support(self, backend)
         
         # Now we must activate the gui pylab wants to use, and fix %run to take
         # plot updates into account
         self.enable_gui(gui)
         self.magics_manager.registry['ExecutionMagics'].default_runner = \
             pt.mpl_runner(self.safe_execfile)
         
         return gui, backend
 
     def enable_pylab(self, gui=None, import_all=True, welcome_message=False):
         """Activate pylab support at runtime.
 
         This turns on support for matplotlib, preloads into the interactive
         namespace all of numpy and pylab, and configures IPython to correctly
         interact with the GUI event loop.  The GUI backend to be used can be
         optionally selected with the optional ``gui`` argument.
         
         This method only adds preloading the namespace to InteractiveShell.enable_matplotlib.
 
         Parameters
         ----------
         gui : optional, string
           If given, dictates the choice of matplotlib GUI backend to use
           (should be one of IPython's supported backends, 'qt', 'osx', 'tk',
           'gtk', 'wx' or 'inline'), otherwise we use the default chosen by
           matplotlib (as dictated by the matplotlib build-time options plus the
           user's matplotlibrc configuration file).  Note that not all backends
           make sense in all contexts, for example a terminal ipython can't
           display figures inline.
         import_all : optional, bool, default: True
           Whether to do `from numpy import *` and `from pylab import *`
           in addition to module imports.
         welcome_message : deprecated
           This argument is ignored, no welcome message will be displayed.
         """
         from IPython.core.pylabtools import import_pylab
         
         gui, backend = self.enable_matplotlib(gui)
         
         # We want to prevent the loading of pylab to pollute the user's
         # namespace as shown by the %who* magics, so we execute the activation
         # code in an empty namespace, and we update *both* user_ns and
         # user_ns_hidden with this information.
         ns = {}
         import_pylab(ns, import_all)
         # warn about clobbered names
         ignored = set(["__builtins__"])
         both = set(ns).intersection(self.user_ns).difference(ignored)
         clobbered = [ name for name in both if self.user_ns[name] is not ns[name] ]
         self.user_ns.update(ns)
         self.user_ns_hidden.update(ns)
         return gui, backend, clobbered
 
     #-------------------------------------------------------------------------
     # Utilities
     #-------------------------------------------------------------------------
 
     def var_expand(self, cmd, depth=0, formatter=DollarFormatter()):
         """Expand python variables in a string.
 
         The depth argument indicates how many frames above the caller should
         be walked to look for the local namespace where to expand variables.
 
         The global namespace for expansion is always the user's interactive
         namespace.
         """
         ns = self.user_ns.copy()
         ns.update(sys._getframe(depth+1).f_locals)
         try:
             # We have to use .vformat() here, because 'self' is a valid and common
             # name, and expanding **ns for .format() would make it collide with
             # the 'self' argument of the method.
             cmd = formatter.vformat(cmd, args=[], kwargs=ns)
         except Exception:
             # if formatter couldn't format, just let it go untransformed
             pass
         return cmd
 
     def mktempfile(self, data=None, prefix='ipython_edit_'):
         """Make a new tempfile and return its filename.
 
         This makes a call to tempfile.mkstemp (created in a tempfile.mkdtemp),
         but it registers the created filename internally so ipython cleans it up
         at exit time.
 
         Optional inputs:
 
           - data(None): if data is given, it gets written out to the temp file
             immediately, and the file is closed again."""
 
         dirname = tempfile.mkdtemp(prefix=prefix)
         self.tempdirs.append(dirname)
 
         handle, filename = tempfile.mkstemp('.py', prefix, dir=dirname)
         self.tempfiles.append(filename)
 
         if data:
             tmp_file = open(filename,'w')
             tmp_file.write(data)
             tmp_file.close()
         return filename
 
     # TODO:  This should be removed when Term is refactored.
     def write(self,data):
         """Write a string to the default output"""
         io.stdout.write(data)
 
     # TODO:  This should be removed when Term is refactored.
     def write_err(self,data):
         """Write a string to the default error output"""
         io.stderr.write(data)
 
     def ask_yes_no(self, prompt, default=None):
         if self.quiet:
             return True
         return ask_yes_no(prompt,default)
 
     def show_usage(self):
         """Show a usage message"""
         page.page(IPython.core.usage.interactive_usage)
 
     def extract_input_lines(self, range_str, raw=False):
         """Return as a string a set of input history slices.
 
         Parameters
         ----------
         range_str : string
             The set of slices is given as a string, like "~5/6-~4/2 4:8 9",
             since this function is for use by magic functions which get their
             arguments as strings. The number before the / is the session
             number: ~n goes n back from the current session.
 
         raw : bool, optional
             By default, the processed input is used.  If this is true, the raw
             input history is used instead.
 
         Notes
         -----
 
         Slices can be described with two notations:
 
         * ``N:M`` -> standard python form, means including items N...(M-1).
         * ``N-M`` -> include items N..M (closed endpoint).
         """
         lines = self.history_manager.get_range_by_str(range_str, raw=raw)
         return "\n".join(x for _, _, x in lines)
 
     def find_user_code(self, target, raw=True, py_only=False, skip_encoding_cookie=True, search_ns=False):
         """Get a code string from history, file, url, or a string or macro.
 
         This is mainly used by magic functions.
 
         Parameters
         ----------
 
         target : str
 
           A string specifying code to retrieve. This will be tried respectively
           as: ranges of input history (see %history for syntax), url,
           correspnding .py file, filename, or an expression evaluating to a
           string or Macro in the user namespace.
 
         raw : bool
           If true (default), retrieve raw history. Has no effect on the other
           retrieval mechanisms.
 
         py_only : bool (default False)
           Only try to fetch python code, do not try alternative methods to decode file
           if unicode fails.
 
         Returns
         -------
         A string of code.
 
         ValueError is raised if nothing is found, and TypeError if it evaluates
         to an object of another type. In each case, .args[0] is a printable
         message.
         """
         code = self.extract_input_lines(target, raw=raw)  # Grab history
         if code:
             return code
         utarget = unquote_filename(target)
         try:
             if utarget.startswith(('http://', 'https://')):
                 return openpy.read_py_url(utarget, skip_encoding_cookie=skip_encoding_cookie)
         except UnicodeDecodeError:
             if not py_only :
                 # Deferred import
                 try:
                     from urllib.request import urlopen  # Py3
                 except ImportError:
                     from urllib import urlopen
                 response = urlopen(target)
                 return response.read().decode('latin1')
             raise ValueError(("'%s' seem to be unreadable.") % utarget)
 
         potential_target = [target]
         try :
             potential_target.insert(0,get_py_filename(target))
         except IOError:
             pass
 
         for tgt in potential_target :
             if os.path.isfile(tgt):                        # Read file
                 try :
                     return openpy.read_py_file(tgt, skip_encoding_cookie=skip_encoding_cookie)
                 except UnicodeDecodeError :
                     if not py_only :
                         with io_open(tgt,'r', encoding='latin1') as f :
                             return f.read()
                     raise ValueError(("'%s' seem to be unreadable.") % target)
             elif os.path.isdir(os.path.expanduser(tgt)):
                 raise ValueError("'%s' is a directory, not a regular file." % target)
 
         if search_ns:
             # Inspect namespace to load object source
             object_info = self.object_inspect(target, detail_level=1)
             if object_info['found'] and object_info['source']:
                 return object_info['source']
 
         try:                                              # User namespace
             codeobj = eval(target, self.user_ns)
         except Exception:
             raise ValueError(("'%s' was not found in history, as a file, url, "
                                 "nor in the user namespace.") % target)
 
         if isinstance(codeobj, string_types):
             return codeobj
         elif isinstance(codeobj, Macro):
             return codeobj.value
 
         raise TypeError("%s is neither a string nor a macro." % target,
                         codeobj)
 
     #-------------------------------------------------------------------------
     # Things related to IPython exiting
     #-------------------------------------------------------------------------
     def atexit_operations(self):
         """This will be executed at the time of exit.
 
         Cleanup operations and saving of persistent data that is done
         unconditionally by IPython should be performed here.
 
         For things that may depend on startup flags or platform specifics (such
         as having readline or not), register a separate atexit function in the
         code that has the appropriate information, rather than trying to
         clutter
         """
         # Close the history session (this stores the end time and line count)
         # this must be *before* the tempfile cleanup, in case of temporary
         # history db
         self.history_manager.end_session()
 
         # Cleanup all tempfiles and folders left around
         for tfile in self.tempfiles:
             try:
                 os.unlink(tfile)
             except OSError:
                 pass
 
         for tdir in self.tempdirs:
             try:
                 os.rmdir(tdir)
             except OSError:
                 pass
 
         # Clear all user namespaces to release all references cleanly.
         self.reset(new_session=False)
 
         # Run user hooks
         self.hooks.shutdown_hook()
 
     def cleanup(self):
         self.restore_sys_module_state()
 
 
 class InteractiveShellABC(with_metaclass(abc.ABCMeta, object)):
     """An abstract base class for InteractiveShell."""
 
 InteractiveShellABC.register(InteractiveShell)

IPython/core/profiledir.py

@@ -1,281 +1,250 b''
 # encoding: utf-8
-"""
-An object for managing IPython profile directories.
-
-Authors:
+"""An object for managing IPython profile directories."""
 
-* Brian Granger
-* Fernando Perez
-* Min RK
-
-"""
-
-#-----------------------------------------------------------------------------
-#  Copyright (C) 2011 The IPython Development Team
-#
-#  Distributed under the terms of the BSD License.  The full license is in
-#  the file COPYING, distributed as part of this software.
-#-----------------------------------------------------------------------------
-
-#-----------------------------------------------------------------------------
-# Imports
-#-----------------------------------------------------------------------------
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
 
 import os
 import shutil
 import errno
 import time
 
 from IPython.config.configurable import LoggingConfigurable
-from IPython.utils.path import get_ipython_package_dir, expand_path
+from IPython.utils.path import get_ipython_package_dir, expand_path, ensure_dir_exists
 from IPython.utils import py3compat
 from IPython.utils.traitlets import Unicode, Bool
 
 #-----------------------------------------------------------------------------
-# Classes and functions
-#-----------------------------------------------------------------------------
-
-
-#-----------------------------------------------------------------------------
 # Module errors
 #-----------------------------------------------------------------------------
 
 class ProfileDirError(Exception):
     pass
 
 
 #-----------------------------------------------------------------------------
 # Class for managing profile directories
 #-----------------------------------------------------------------------------
 
 class ProfileDir(LoggingConfigurable):
     """An object to manage the profile directory and its resources.
 
     The profile directory is used by all IPython applications, to manage
     configuration, logging and security.
 
     This object knows how to find, create and manage these directories. This
     should be used by any code that wants to handle profiles.
     """
 
     security_dir_name = Unicode('security')
     log_dir_name = Unicode('log')
     startup_dir_name = Unicode('startup')
     pid_dir_name = Unicode('pid')
     static_dir_name = Unicode('static')
     security_dir = Unicode(u'')
     log_dir = Unicode(u'')
     startup_dir = Unicode(u'')
     pid_dir = Unicode(u'')
     static_dir = Unicode(u'')
 
     location = Unicode(u'', config=True,
         help="""Set the profile location directly. This overrides the logic used by the
         `profile` option.""",
         )
 
     _location_isset = Bool(False) # flag for detecting multiply set location
 
     def _location_changed(self, name, old, new):
         if self._location_isset:
             raise RuntimeError("Cannot set profile location more than once.")
         self._location_isset = True
-        num_tries = 0
-        max_tries = 5
-        while not os.path.isdir(new):
-            try:
-                os.makedirs(new)
-            except OSError:
-                if num_tries > max_tries:
-                    raise
-                num_tries += 1
-                time.sleep(0.5)
+        ensure_dir_exists(new)
 
         # ensure config files exist:
         self.security_dir = os.path.join(new, self.security_dir_name)
         self.log_dir = os.path.join(new, self.log_dir_name)
         self.startup_dir = os.path.join(new, self.startup_dir_name)
         self.pid_dir = os.path.join(new, self.pid_dir_name)
         self.static_dir = os.path.join(new, self.static_dir_name)
         self.check_dirs()
 
     def _log_dir_changed(self, name, old, new):
         self.check_log_dir()
 
     def _mkdir(self, path, mode=None):
         """ensure a directory exists at a given path
 
         This is a version of os.mkdir, with the following differences:
 
         - returns True if it created the directory, False otherwise
         - ignores EEXIST, protecting against race conditions where
           the dir may have been created in between the check and
           the creation
         - sets permissions if requested and the dir already exists
         """
         if os.path.exists(path):
             if mode and os.stat(path).st_mode != mode:
                 try:
                     os.chmod(path, mode)
                 except OSError:
                     self.log.warn(
                         "Could not set permissions on %s",
                         path
                     )
             return False
         try:
             if mode:
                 os.mkdir(path, mode)
             else:
                 os.mkdir(path)
         except OSError as e:
             if e.errno == errno.EEXIST:
                 return False
             else:
                 raise
 
         return True
 
     def check_log_dir(self):
         self._mkdir(self.log_dir)
 
     def _startup_dir_changed(self, name, old, new):
         self.check_startup_dir()
 
     def check_startup_dir(self):
         self._mkdir(self.startup_dir)
 
         readme = os.path.join(self.startup_dir, 'README')
         src = os.path.join(get_ipython_package_dir(), u'config', u'profile', u'README_STARTUP')
 
         if not os.path.exists(src):
             self.log.warn("Could not copy README_STARTUP to startup dir. Source file %s does not exist.", src)
 
         if os.path.exists(src) and not os.path.exists(readme):
             shutil.copy(src, readme)
 
     def _security_dir_changed(self, name, old, new):
         self.check_security_dir()
 
     def check_security_dir(self):
         self._mkdir(self.security_dir, 0o40700)
 
     def _pid_dir_changed(self, name, old, new):
         self.check_pid_dir()
 
     def check_pid_dir(self):
         self._mkdir(self.pid_dir, 0o40700)
 
     def _static_dir_changed(self, name, old, new):
         self.check_startup_dir()
 
     def check_static_dir(self):
         self._mkdir(self.static_dir)
         custom = os.path.join(self.static_dir, 'custom')
         self._mkdir(custom)
         from IPython.html import DEFAULT_STATIC_FILES_PATH
         for fname in ('custom.js', 'custom.css'):
             src = os.path.join(DEFAULT_STATIC_FILES_PATH, 'custom', fname)
             dest = os.path.join(custom, fname)
             if not os.path.exists(src):
                 self.log.warn("Could not copy default file to static dir. Source file %s does not exist.", src)
                 continue
             if not os.path.exists(dest):
                 shutil.copy(src, dest)
 
     def check_dirs(self):
         self.check_security_dir()
         self.check_log_dir()
         self.check_pid_dir()
         self.check_startup_dir()
         self.check_static_dir()
 
     def copy_config_file(self, config_file, path=None, overwrite=False):
         """Copy a default config file into the active profile directory.
 
         Default configuration files are kept in :mod:`IPython.config.default`.
         This function moves these from that location to the working profile
         directory.
         """
         dst = os.path.join(self.location, config_file)
         if os.path.isfile(dst) and not overwrite:
             return False
         if path is None:
             path = os.path.join(get_ipython_package_dir(), u'config', u'profile', u'default')
         src = os.path.join(path, config_file)
         shutil.copy(src, dst)
         return True
 
     @classmethod
     def create_profile_dir(cls, profile_dir, config=None):
         """Create a new profile directory given a full path.
 
         Parameters
         ----------
         profile_dir : str
             The full path to the profile directory.  If it does exist, it will
             be used.  If not, it will be created.
         """
         return cls(location=profile_dir, config=config)
 
     @classmethod
     def create_profile_dir_by_name(cls, path, name=u'default', config=None):
         """Create a profile dir by profile name and path.
 
         Parameters
         ----------
         path : unicode
             The path (directory) to put the profile directory in.
         name : unicode
             The name of the profile.  The name of the profile directory will
             be "profile_<profile>".
         """
         if not os.path.isdir(path):
             raise ProfileDirError('Directory not found: %s' % path)
         profile_dir = os.path.join(path, u'profile_' + name)
         return cls(location=profile_dir, config=config)
 
     @classmethod
     def find_profile_dir_by_name(cls, ipython_dir, name=u'default', config=None):
         """Find an existing profile dir by profile name, return its ProfileDir.
 
         This searches through a sequence of paths for a profile dir.  If it
         is not found, a :class:`ProfileDirError` exception will be raised.
 
         The search path algorithm is:
         1. ``py3compat.getcwd()``
         2. ``ipython_dir``
 
         Parameters
         ----------
         ipython_dir : unicode or str
             The IPython directory to use.
         name : unicode or str
             The name of the profile.  The name of the profile directory
             will be "profile_<profile>".
         """
         dirname = u'profile_' + name
         paths = [py3compat.getcwd(), ipython_dir]
         for p in paths:
             profile_dir = os.path.join(p, dirname)
             if os.path.isdir(profile_dir):
                 return cls(location=profile_dir, config=config)
         else:
             raise ProfileDirError('Profile directory not found in paths: %s' % dirname)
 
     @classmethod
     def find_profile_dir(cls, profile_dir, config=None):
         """Find/create a profile dir and return its ProfileDir.
 
         This will create the profile directory if it doesn't exist.
 
         Parameters
         ----------
         profile_dir : unicode or str
             The path of the profile directory.  This is expanded using
             :func:`IPython.utils.genutils.expand_path`.
         """
         profile_dir = expand_path(profile_dir)
         if not os.path.isdir(profile_dir):
             raise ProfileDirError('Profile directory not found: %s' % profile_dir)
         return cls(location=profile_dir, config=config)

IPython/html/nbextensions.py

@@ -1,268 +1,263 b''
 # coding: utf-8
 """Utilities for installing Javascript extensions for the notebook"""
 
-#-----------------------------------------------------------------------------
-#  Copyright (C) 2014 The IPython Development Team
-#
-#  Distributed under the terms of the BSD License.  The full license is in
-#  the file COPYING, distributed as part of this software.
-#-----------------------------------------------------------------------------
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
 
 from __future__ import print_function
 
 import os
 import shutil
 import tarfile
 import zipfile
 from os.path import basename, join as pjoin
 
 # Deferred imports
 try:
     from urllib.parse import urlparse  # Py3
     from urllib.request import urlretrieve
 except ImportError:
     from urlparse import urlparse
     from urllib import urlretrieve
 
-from IPython.utils.path import get_ipython_dir
+from IPython.utils.path import get_ipython_dir, ensure_dir_exists
 from IPython.utils.py3compat import string_types, cast_unicode_py2
 from IPython.utils.tempdir import TemporaryDirectory
 
 
 def _should_copy(src, dest, verbose=1):
     """should a file be copied?"""
     if not os.path.exists(dest):
         return True
     if os.stat(dest).st_mtime < os.stat(src).st_mtime:
         if verbose >= 2:
             print("%s is out of date" % dest)
         return True
     if verbose >= 2:
         print("%s is up to date" % dest)
     return False
 
 
 def _maybe_copy(src, dest, verbose=1):
     """copy a file if it needs updating"""
     if _should_copy(src, dest, verbose):
         if verbose >= 1:
             print("copying %s -> %s" % (src, dest))
         shutil.copy2(src, dest)
 
 
 def _safe_is_tarfile(path):
     """safe version of is_tarfile, return False on IOError"""
     try:
         return tarfile.is_tarfile(path)
     except IOError:
         return False
 
 
 def check_nbextension(files, ipython_dir=None):
     """Check whether nbextension files have been installed
     
     files should be a list of relative paths within nbextensions.
     
     Returns True if all files are found, False if any are missing.
     """
     ipython_dir = ipython_dir or get_ipython_dir()
     nbext = pjoin(ipython_dir, u'nbextensions')
     # make sure nbextensions dir exists
     if not os.path.exists(nbext):
         return False
     
     if isinstance(files, string_types):
         # one file given, turn it into a list
         files = [files]
     
     return all(os.path.exists(pjoin(nbext, f)) for f in files)
 
 
 def install_nbextension(files, overwrite=False, symlink=False, ipython_dir=None, verbose=1):
     """Install a Javascript extension for the notebook
     
     Stages files and/or directories into IPYTHONDIR/nbextensions.
     By default, this compares modification time, and only stages files that need updating.
     If `overwrite` is specified, matching files are purged before proceeding.
     
     Parameters
     ----------
     
     files : list(paths or URLs)
         One or more paths or URLs to existing files directories to install.
         These will be installed with their base name, so '/path/to/foo'
         will install to 'nbextensions/foo'.
         Archives (zip or tarballs) will be extracted into the nbextensions directory.
     overwrite : bool [default: False]
         If True, always install the files, regardless of what may already be installed.
     symlink : bool [default: False]
         If True, create a symlink in nbextensions, rather than copying files.
         Not allowed with URLs or archives.
     ipython_dir : str [optional]
         The path to an IPython directory, if the default value is not desired.
         get_ipython_dir() is used by default.
     verbose : int [default: 1]
         Set verbosity level. The default is 1, where file actions are printed.
         set verbose=2 for more output, or verbose=0 for silence.
     """
     
     ipython_dir = ipython_dir or get_ipython_dir()
     nbext = pjoin(ipython_dir, u'nbextensions')
     # make sure nbextensions dir exists
-    if not os.path.exists(nbext):
-        os.makedirs(nbext)
+    ensure_dir_exists(nbext)
     
     if isinstance(files, string_types):
         # one file given, turn it into a list
         files = [files]
     
     for path in map(cast_unicode_py2, files):
         
         if path.startswith(('https://', 'http://')):
             if symlink:
                 raise ValueError("Cannot symlink from URLs")
             # Given a URL, download it
             with TemporaryDirectory() as td:
                 filename = urlparse(path).path.split('/')[-1]
                 local_path = os.path.join(td, filename)
                 if verbose >= 1:
                     print("downloading %s to %s" % (path, local_path))
                 urlretrieve(path, local_path)
                 # now install from the local copy
                 install_nbextension(local_path, overwrite, symlink, ipython_dir, verbose)
             continue
         
         # handle archives
         archive = None
         if path.endswith('.zip'):
             archive = zipfile.ZipFile(path)
         elif _safe_is_tarfile(path):
             archive = tarfile.open(path)
         
         if archive:
             if symlink:
                 raise ValueError("Cannot symlink from archives")
             if verbose >= 1:
                 print("extracting %s to %s" % (path, nbext))
             archive.extractall(nbext)
             archive.close()
             continue
         
         dest = pjoin(nbext, basename(path))
         if overwrite and os.path.exists(dest):
             if verbose >= 1:
                 print("removing %s" % dest)
             if os.path.isdir(dest):
                 shutil.rmtree(dest)
             else:
                 os.remove(dest)
         
         if symlink:
             path = os.path.abspath(path)
             if not os.path.exists(dest):
                 if verbose >= 1:
                     print("symlink %s -> %s" % (dest, path))
                 os.symlink(path, dest)
             continue
 
         if os.path.isdir(path):
             strip_prefix_len = len(path) - len(basename(path))
             for parent, dirs, files in os.walk(path):
                 dest_dir = pjoin(nbext, parent[strip_prefix_len:])
                 if not os.path.exists(dest_dir):
                     if verbose >= 2:
                         print("making directory %s" % dest_dir)
                     os.makedirs(dest_dir)
                 for file in files:
                     src = pjoin(parent, file)
                     # print("%r, %r" % (dest_dir, file))
                     dest = pjoin(dest_dir, file)
                     _maybe_copy(src, dest, verbose)
         else:
             src = path
             _maybe_copy(src, dest, verbose)
 
 #----------------------------------------------------------------------
 # install nbextension app
 #----------------------------------------------------------------------
 
 from IPython.utils.traitlets import Bool, Enum
 from IPython.core.application import BaseIPythonApplication
 
 flags = {
     "overwrite" : ({
         "NBExtensionApp" : {
             "overwrite" : True,
         }}, "Force overwrite of existing files"
     ),
     "debug" : ({
         "NBExtensionApp" : {
             "verbose" : 2,
         }}, "Extra output"
     ),
     "quiet" : ({
         "NBExtensionApp" : {
             "verbose" : 0,
         }}, "Minimal output"
     ),
     "symlink" : ({
         "NBExtensionApp" : {
             "symlink" : True,
         }}, "Create symlinks instead of copying files"
     ),
 }
 flags['s'] = flags['symlink']
 
 aliases = {
     "ipython-dir" : "NBExtensionApp.ipython_dir"
 }
 
 class NBExtensionApp(BaseIPythonApplication):
     """Entry point for installing notebook extensions"""
     
     description = """Install IPython notebook extensions
     
     Usage
     
         ipython install-nbextension file [more files, folders, archives or urls]
     
     This copies files and/or folders into the IPython nbextensions directory.
     If a URL is given, it will be downloaded.
     If an archive is given, it will be extracted into nbextensions.
     If the requested files are already up to date, no action is taken
     unless --overwrite is specified.
     """
     
     examples = """
     ipython install-nbextension /path/to/d3.js /path/to/myextension
     """
     aliases = aliases
     flags = flags
     
     overwrite = Bool(False, config=True, help="Force overwrite of existing files")
     symlink = Bool(False, config=True, help="Create symlinks instead of copying files")
     verbose = Enum((0,1,2), default_value=1, config=True,
         help="Verbosity level"
     )
     
     def install_extensions(self):
         install_nbextension(self.extra_args,
             overwrite=self.overwrite,
             symlink=self.symlink,
             verbose=self.verbose,
             ipython_dir=self.ipython_dir,
         )
     
     def start(self):
         if not self.extra_args:
             nbext = pjoin(self.ipython_dir, u'nbextensions')
             print("Notebook extensions in %s:" % nbext)
             for ext in os.listdir(nbext):
                 print(u"    %s" % ext)
         else:
             self.install_extensions()
 
 
 if __name__ == '__main__':
     NBExtensionApp.launch_instance()
     
  No newline at end of file

IPython/html/services/notebooks/filenbmanager.py

@@ -1,486 +1,470 b''
-"""A notebook manager that uses the local file system for storage.
+"""A notebook manager that uses the local file system for storage."""
 
-Authors:
-
-* Brian Granger
-* Zach Sailer
-"""
-
-#-----------------------------------------------------------------------------
-#  Copyright (C) 2011  The IPython Development Team
-#
-#  Distributed under the terms of the BSD License.  The full license is in
-#  the file COPYING, distributed as part of this software.
-#-----------------------------------------------------------------------------
-
-#-----------------------------------------------------------------------------
-# Imports
-#-----------------------------------------------------------------------------
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
 
 import io
 import os
 import glob
 import shutil
 
 from tornado import web
 
 from .nbmanager import NotebookManager
 from IPython.nbformat import current
+from IPython.utils.path import ensure_dir_exists
 from IPython.utils.traitlets import Unicode, Bool, TraitError
 from IPython.utils.py3compat import getcwd
 from IPython.utils import tz
 from IPython.html.utils import is_hidden, to_os_path
 
 def sort_key(item):
     """Case-insensitive sorting."""
     return item['name'].lower()
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
 
 class FileNotebookManager(NotebookManager):
     
     save_script = Bool(False, config=True,
         help="""Automatically create a Python script when saving the notebook.
         
         For easier use of import, %run and %load across notebooks, a
         <notebook-name>.py script will be created next to any
         <notebook-name>.ipynb on each save.  This can also be set with the
         short `--script` flag.
         """
     )
     notebook_dir = Unicode(getcwd(), config=True)
     
     def _notebook_dir_changed(self, name, old, new):
         """Do a bit of validation of the notebook dir."""
         if not os.path.isabs(new):
             # If we receive a non-absolute path, make it absolute.
             self.notebook_dir = os.path.abspath(new)
             return
         if not os.path.exists(new) or not os.path.isdir(new):
             raise TraitError("notebook dir %r is not a directory" % new)
     
     checkpoint_dir = Unicode('.ipynb_checkpoints', config=True,
         help="""The directory name in which to keep notebook checkpoints
         
         This is a path relative to the notebook's own directory.
         
         By default, it is .ipynb_checkpoints
         """
     )
     
     def _copy(self, src, dest):
         """copy src to dest
         
         like shutil.copy2, but log errors in copystat
         """
         shutil.copyfile(src, dest)
         try:
             shutil.copystat(src, dest)
         except OSError as e:
             self.log.debug("copystat on %s failed", dest, exc_info=True)
     
     def get_notebook_names(self, path=''):
         """List all notebook names in the notebook dir and path."""
         path = path.strip('/')
         if not os.path.isdir(self._get_os_path(path=path)):
             raise web.HTTPError(404, 'Directory not found: ' + path)
         names = glob.glob(self._get_os_path('*'+self.filename_ext, path))
         names = [os.path.basename(name)
                  for name in names]
         return names
 
     def path_exists(self, path):
         """Does the API-style path (directory) actually exist?
         
         Parameters
         ----------
         path : string
             The path to check. This is an API path (`/` separated,
             relative to base notebook-dir).
         
         Returns
         -------
         exists : bool
             Whether the path is indeed a directory.
         """
         path = path.strip('/')
         os_path = self._get_os_path(path=path)
         return os.path.isdir(os_path)
 
     def is_hidden(self, path):
         """Does the API style path correspond to a hidden directory or file?
         
         Parameters
         ----------
         path : string
             The path to check. This is an API path (`/` separated,
             relative to base notebook-dir).
         
         Returns
         -------
         exists : bool
             Whether the path is hidden.
         
         """
         path = path.strip('/')
         os_path = self._get_os_path(path=path)
         return is_hidden(os_path, self.notebook_dir)
 
     def _get_os_path(self, name=None, path=''):
         """Given a notebook name and a URL path, return its file system
         path.
 
         Parameters
         ----------
         name : string
             The name of a notebook file with the .ipynb extension
         path : string
             The relative URL path (with '/' as separator) to the named
             notebook.
 
         Returns
         -------
         path : string
             A file system path that combines notebook_dir (location where
             server started), the relative path, and the filename with the
             current operating system's url.
         """
         if name is not None:
             path = path + '/' + name
         return to_os_path(path, self.notebook_dir)
 
     def notebook_exists(self, name, path=''):
         """Returns a True if the notebook exists. Else, returns False.
 
         Parameters
         ----------
         name : string
             The name of the notebook you are checking.
         path : string
             The relative path to the notebook (with '/' as separator)
 
         Returns
         -------
         bool
         """
         path = path.strip('/')
         nbpath = self._get_os_path(name, path=path)
         return os.path.isfile(nbpath)
 
     # TODO: Remove this after we create the contents web service and directories are
     # no longer listed by the notebook web service.
     def list_dirs(self, path):
         """List the directories for a given API style path."""
         path = path.strip('/')
         os_path = self._get_os_path('', path)
         if not os.path.isdir(os_path):
             raise web.HTTPError(404, u'directory does not exist: %r' % os_path)
         elif is_hidden(os_path, self.notebook_dir):
             self.log.info("Refusing to serve hidden directory, via 404 Error")
             raise web.HTTPError(404, u'directory does not exist: %r' % os_path)
         dir_names = os.listdir(os_path)
         dirs = []
         for name in dir_names:
             os_path = self._get_os_path(name, path)
             if os.path.isdir(os_path) and not is_hidden(os_path, self.notebook_dir)\
                     and self.should_list(name):
                 try:
                     model = self.get_dir_model(name, path)
                 except IOError:
                     pass
                 dirs.append(model)
         dirs = sorted(dirs, key=sort_key)
         return dirs
 
     # TODO: Remove this after we create the contents web service and directories are
     # no longer listed by the notebook web service.
     def get_dir_model(self, name, path=''):
         """Get the directory model given a directory name and its API style path"""
         path = path.strip('/')
         os_path = self._get_os_path(name, path)
         if not os.path.isdir(os_path):
             raise IOError('directory does not exist: %r' % os_path)
         info = os.stat(os_path)
         last_modified = tz.utcfromtimestamp(info.st_mtime)
         created = tz.utcfromtimestamp(info.st_ctime)
         # Create the notebook model.
         model ={}
         model['name'] = name
         model['path'] = path
         model['last_modified'] = last_modified
         model['created'] = created
         model['type'] = 'directory'
         return model
 
     def list_notebooks(self, path):
         """Returns a list of dictionaries that are the standard model
         for all notebooks in the relative 'path'.
         
         Parameters
         ----------
         path : str
             the URL path that describes the relative path for the
             listed notebooks
         
         Returns
         -------
         notebooks : list of dicts
             a list of the notebook models without 'content'
         """
         path = path.strip('/')
         notebook_names = self.get_notebook_names(path)
         notebooks = [self.get_notebook(name, path, content=False)
                         for name in notebook_names if self.should_list(name)]
         notebooks = sorted(notebooks, key=sort_key)
         return notebooks
 
     def get_notebook(self, name, path='', content=True):
         """ Takes a path and name for a notebook and returns its model
         
         Parameters
         ----------
         name : str
             the name of the notebook
         path : str
             the URL path that describes the relative path for
             the notebook
             
         Returns
         -------
         model : dict
             the notebook model. If contents=True, returns the 'contents' 
             dict in the model as well.
         """
         path = path.strip('/')
         if not self.notebook_exists(name=name, path=path):
             raise web.HTTPError(404, u'Notebook does not exist: %s' % name)
         os_path = self._get_os_path(name, path)
         info = os.stat(os_path)
         last_modified = tz.utcfromtimestamp(info.st_mtime)
         created = tz.utcfromtimestamp(info.st_ctime)
         # Create the notebook model.
         model ={}
         model['name'] = name
         model['path'] = path
         model['last_modified'] = last_modified
         model['created'] = created
         model['type'] = 'notebook'
         if content:
             with io.open(os_path, 'r', encoding='utf-8') as f:
                 try:
                     nb = current.read(f, u'json')
                 except Exception as e:
                     raise web.HTTPError(400, u"Unreadable Notebook: %s %s" % (os_path, e))
             self.mark_trusted_cells(nb, name, path)
             model['content'] = nb
         return model
 
     def save_notebook(self, model, name='', path=''):
         """Save the notebook model and return the model with no content."""
         path = path.strip('/')
 
         if 'content' not in model:
             raise web.HTTPError(400, u'No notebook JSON data provided')
 
         # One checkpoint should always exist
         if self.notebook_exists(name, path) and not self.list_checkpoints(name, path):
             self.create_checkpoint(name, path)
 
         new_path = model.get('path', path).strip('/')
         new_name = model.get('name', name)
 
         if path != new_path or name != new_name:
             self.rename_notebook(name, path, new_name, new_path)
 
         # Save the notebook file
         os_path = self._get_os_path(new_name, new_path)
         nb = current.to_notebook_json(model['content'])
         
         self.check_and_sign(nb, new_name, new_path)
         
         if 'name' in nb['metadata']:
             nb['metadata']['name'] = u''
         try:
             self.log.debug("Autosaving notebook %s", os_path)
             with io.open(os_path, 'w', encoding='utf-8') as f:
                 current.write(nb, f, u'json')
         except Exception as e:
             raise web.HTTPError(400, u'Unexpected error while autosaving notebook: %s %s' % (os_path, e))
 
         # Save .py script as well
         if self.save_script:
             py_path = os.path.splitext(os_path)[0] + '.py'
             self.log.debug("Writing script %s", py_path)
             try:
                 with io.open(py_path, 'w', encoding='utf-8') as f:
                     current.write(nb, f, u'py')
             except Exception as e:
                 raise web.HTTPError(400, u'Unexpected error while saving notebook as script: %s %s' % (py_path, e))
 
         model = self.get_notebook(new_name, new_path, content=False)
         return model
 
     def update_notebook(self, model, name, path=''):
         """Update the notebook's path and/or name"""
         path = path.strip('/')
         new_name = model.get('name', name)
         new_path = model.get('path', path).strip('/')
         if path != new_path or name != new_name:
             self.rename_notebook(name, path, new_name, new_path)
         model = self.get_notebook(new_name, new_path, content=False)
         return model
 
     def delete_notebook(self, name, path=''):
         """Delete notebook by name and path."""
         path = path.strip('/')
         os_path = self._get_os_path(name, path)
         if not os.path.isfile(os_path):
             raise web.HTTPError(404, u'Notebook does not exist: %s' % os_path)
         
         # clear checkpoints
         for checkpoint in self.list_checkpoints(name, path):
             checkpoint_id = checkpoint['id']
             cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
             if os.path.isfile(cp_path):
                 self.log.debug("Unlinking checkpoint %s", cp_path)
                 os.unlink(cp_path)
         
         self.log.debug("Unlinking notebook %s", os_path)
         os.unlink(os_path)
 
     def rename_notebook(self, old_name, old_path, new_name, new_path):
         """Rename a notebook."""
         old_path = old_path.strip('/')
         new_path = new_path.strip('/')
         if new_name == old_name and new_path == old_path:
             return
         
         new_os_path = self._get_os_path(new_name, new_path)
         old_os_path = self._get_os_path(old_name, old_path)
 
         # Should we proceed with the move?
         if os.path.isfile(new_os_path):
             raise web.HTTPError(409, u'Notebook with name already exists: %s' % new_os_path)
         if self.save_script:
             old_py_path = os.path.splitext(old_os_path)[0] + '.py'
             new_py_path = os.path.splitext(new_os_path)[0] + '.py'
             if os.path.isfile(new_py_path):
                 raise web.HTTPError(409, u'Python script with name already exists: %s' % new_py_path)
 
         # Move the notebook file
         try:
             shutil.move(old_os_path, new_os_path)
         except Exception as e:
             raise web.HTTPError(500, u'Unknown error renaming notebook: %s %s' % (old_os_path, e))
 
         # Move the checkpoints
         old_checkpoints = self.list_checkpoints(old_name, old_path)
         for cp in old_checkpoints:
             checkpoint_id = cp['id']
             old_cp_path = self.get_checkpoint_path(checkpoint_id, old_name, old_path)
             new_cp_path = self.get_checkpoint_path(checkpoint_id, new_name, new_path)
             if os.path.isfile(old_cp_path):
                 self.log.debug("Renaming checkpoint %s -> %s", old_cp_path, new_cp_path)
                 shutil.move(old_cp_path, new_cp_path)
 
         # Move the .py script
         if self.save_script:
             shutil.move(old_py_path, new_py_path)
   
     # Checkpoint-related utilities
     
     def get_checkpoint_path(self, checkpoint_id, name, path=''):
         """find the path to a checkpoint"""
         path = path.strip('/')
         basename, _ = os.path.splitext(name)
         filename = u"{name}-{checkpoint_id}{ext}".format(
             name=basename,
             checkpoint_id=checkpoint_id,
             ext=self.filename_ext,
         )
         os_path = self._get_os_path(path=path)
         cp_dir = os.path.join(os_path, self.checkpoint_dir)
-        if not os.path.exists(cp_dir):
-            os.mkdir(cp_dir)
+        ensure_dir_exists(cp_dir)
         cp_path = os.path.join(cp_dir, filename)
         return cp_path
 
     def get_checkpoint_model(self, checkpoint_id, name, path=''):
         """construct the info dict for a given checkpoint"""
         path = path.strip('/')
         cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
         stats = os.stat(cp_path)
         last_modified = tz.utcfromtimestamp(stats.st_mtime)
         info = dict(
             id = checkpoint_id,
             last_modified = last_modified,
         )
         return info
         
     # public checkpoint API
     
     def create_checkpoint(self, name, path=''):
         """Create a checkpoint from the current state of a notebook"""
         path = path.strip('/')
         nb_path = self._get_os_path(name, path)
         # only the one checkpoint ID:
         checkpoint_id = u"checkpoint"
         cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
         self.log.debug("creating checkpoint for notebook %s", name)
-        if not os.path.exists(self.checkpoint_dir):
-            os.mkdir(self.checkpoint_dir)
         self._copy(nb_path, cp_path)
         
         # return the checkpoint info
         return self.get_checkpoint_model(checkpoint_id, name, path)
     
     def list_checkpoints(self, name, path=''):
         """list the checkpoints for a given notebook
         
         This notebook manager currently only supports one checkpoint per notebook.
         """
         path = path.strip('/')
         checkpoint_id = "checkpoint"
         os_path = self.get_checkpoint_path(checkpoint_id, name, path)
         if not os.path.exists(os_path):
             return []
         else:
             return [self.get_checkpoint_model(checkpoint_id, name, path)]
         
     
     def restore_checkpoint(self, checkpoint_id, name, path=''):
         """restore a notebook to a checkpointed state"""
         path = path.strip('/')
         self.log.info("restoring Notebook %s from checkpoint %s", name, checkpoint_id)
         nb_path = self._get_os_path(name, path)
         cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
         if not os.path.isfile(cp_path):
             self.log.debug("checkpoint file does not exist: %s", cp_path)
             raise web.HTTPError(404,
                 u'Notebook checkpoint does not exist: %s-%s' % (name, checkpoint_id)
             )
         # ensure notebook is readable (never restore from an unreadable notebook)
         with io.open(cp_path, 'r', encoding='utf-8') as f:
             current.read(f, u'json')
         self._copy(cp_path, nb_path)
         self.log.debug("copying %s -> %s", cp_path, nb_path)
     
     def delete_checkpoint(self, checkpoint_id, name, path=''):
         """delete a notebook's checkpoint"""
         path = path.strip('/')
         cp_path = self.get_checkpoint_path(checkpoint_id, name, path)
         if not os.path.isfile(cp_path):
             raise web.HTTPError(404,
                 u'Notebook checkpoint does not exist: %s%s-%s' % (path, name, checkpoint_id)
             )
         self.log.debug("unlinking %s", cp_path)
         os.unlink(cp_path)
     
     def info_string(self):
         return "Serving notebooks from local directory: %s" % self.notebook_dir
 
     def get_kernel_path(self, name, path='', model=None):
         """ Return the path to start kernel in """
         return os.path.join(self.notebook_dir, path)

IPython/nbconvert/writers/files.py

@@ -1,111 +1,111 b''
 """Contains writer for writing nbconvert output to filesystem."""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 import io
 import os
 import glob
 
 from IPython.utils.traitlets import Unicode
-from IPython.utils.path import link_or_copy
+from IPython.utils.path import link_or_copy, ensure_dir_exists
 from IPython.utils.py3compat import unicode_type
 
 from .base import WriterBase
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
 
 class FilesWriter(WriterBase):
     """Consumes nbconvert output and produces files."""
 
 
     build_directory = Unicode("", config=True,
                               help="""Directory to write output to.  Leave blank
                               to output to the current directory""")
 
 
     # Make sure that the output directory exists.
     def _build_directory_changed(self, name, old, new):
-        if new and not os.path.isdir(new):
-            os.makedirs(new)
+        if new:
+            ensure_dir_exists(new)
 
 
     def __init__(self, **kw):
         super(FilesWriter, self).__init__(**kw)
         self._build_directory_changed('build_directory', self.build_directory, 
                                       self.build_directory)
     
     def _makedir(self, path):
         """Make a directory if it doesn't already exist"""
-        if path and not os.path.isdir(path):
+        if path:
             self.log.info("Making directory %s", path)
-            os.makedirs(path)
+            ensure_dir_exists(path)
 
     def write(self, output, resources, notebook_name=None, **kw):
             """
             Consume and write Jinja output to the file system.  Output directory
             is set via the 'build_directory' variable of this instance (a 
             configurable).
 
             See base for more...
             """
 
             # Verify that a notebook name is provided.
             if notebook_name is None:
                 raise TypeError('notebook_name')
 
             # Pull the extension and subdir from the resources dict.
             output_extension = resources.get('output_extension', None)
 
             # Write all of the extracted resources to the destination directory.
             # NOTE: WE WRITE EVERYTHING AS-IF IT'S BINARY.  THE EXTRACT FIG
             # PREPROCESSOR SHOULD HANDLE UNIX/WINDOWS LINE ENDINGS...
             for filename, data in resources.get('outputs', {}).items():
 
                 # Determine where to write the file to
                 dest = os.path.join(self.build_directory, filename)
                 path = os.path.dirname(dest)
                 self._makedir(path)
 
                 # Write file
                 self.log.debug("Writing %i bytes to support file %s", len(data), dest)
                 with io.open(dest, 'wb') as f:
                     f.write(data)
 
             # Copy referenced files to output directory
             if self.build_directory:
                 for filename in self.files:
 
                     # Copy files that match search pattern
                     for matching_filename in glob.glob(filename):
 
                         # Make sure folder exists.
                         dest = os.path.join(self.build_directory, filename)
                         path = os.path.dirname(dest)
                         self._makedir(path)
 
                         # Copy if destination is different.
                         if not os.path.normpath(dest) == os.path.normpath(matching_filename):
                             self.log.info("Linking %s -> %s", matching_filename, dest)
                             link_or_copy(matching_filename, dest)
 
             # Determine where to write conversion results.
             if output_extension is not None:
                 dest = notebook_name + '.' + output_extension
             else:
                 dest = notebook_name
             if self.build_directory:
                 dest = os.path.join(self.build_directory, dest)
 
             # Write conversion results.
             self.log.info("Writing %i bytes to %s", len(output), dest)
             if isinstance(output, unicode_type):
                 with io.open(dest, 'w', encoding='utf-8') as f:
                     f.write(output)
             else:
                 with io.open(dest, 'wb') as f:
                     f.write(output)
                 
             return dest

IPython/parallel/apps/launcher.py

@@ -1,1463 +1,1447 b''
 # encoding: utf-8
-"""
-Facilities for launching IPython processes asynchronously.
-
-Authors:
+"""Facilities for launching IPython processes asynchronously."""
 
-* Brian Granger
-* MinRK
-"""
-
-#-----------------------------------------------------------------------------
-#  Copyright (C) 2008-2011  The IPython Development Team
-#
-#  Distributed under the terms of the BSD License.  The full license is in
-#  the file COPYING, distributed as part of this software.
-#-----------------------------------------------------------------------------
-
-#-----------------------------------------------------------------------------
-# Imports
-#-----------------------------------------------------------------------------
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
 
 import copy
 import logging
 import os
 import pipes
 import stat
 import sys
 import time
 
 # signal imports, handling various platforms, versions
 
 from signal import SIGINT, SIGTERM
 try:
     from signal import SIGKILL
 except ImportError:
     # Windows
     SIGKILL=SIGTERM
 
 try:
     # Windows >= 2.7, 3.2
     from signal import CTRL_C_EVENT as SIGINT
 except ImportError:
     pass
 
 from subprocess import Popen, PIPE, STDOUT
 try:
     from subprocess import check_output
 except ImportError:
     # pre-2.7, define check_output with Popen
     def check_output(*args, **kwargs):
         kwargs.update(dict(stdout=PIPE))
         p = Popen(*args, **kwargs)
         out,err = p.communicate()
         return out
 
 from zmq.eventloop import ioloop
 
 from IPython.config.application import Application
 from IPython.config.configurable import LoggingConfigurable
 from IPython.utils.text import EvalFormatter
 from IPython.utils.traitlets import (
     Any, Integer, CFloat, List, Unicode, Dict, Instance, HasTraits, CRegExp
 )
 from IPython.utils.encoding import DEFAULT_ENCODING
-from IPython.utils.path import get_home_dir
+from IPython.utils.path import get_home_dir, ensure_dir_exists
 from IPython.utils.process import find_cmd, FindCmdError
 from IPython.utils.py3compat import iteritems, itervalues
 
 from .win32support import forward_read_events
 
 from .winhpcjob import IPControllerTask, IPEngineTask, IPControllerJob, IPEngineSetJob
 
 WINDOWS = os.name == 'nt'
 
 #-----------------------------------------------------------------------------
 # Paths to the kernel apps
 #-----------------------------------------------------------------------------
 
 ipcluster_cmd_argv = [sys.executable, "-m", "IPython.parallel.cluster"]
 
 ipengine_cmd_argv = [sys.executable, "-m", "IPython.parallel.engine"]
 
 ipcontroller_cmd_argv = [sys.executable, "-m", "IPython.parallel.controller"]
 
 if WINDOWS and sys.version_info < (3,):
     # `python -m package` doesn't work on Windows Python 2,
     # but `python -m module` does.
     ipengine_cmd_argv = [sys.executable, "-m", "IPython.parallel.apps.ipengineapp"]
     ipcontroller_cmd_argv = [sys.executable, "-m", "IPython.parallel.apps.ipcontrollerapp"]
 
 #-----------------------------------------------------------------------------
 # Base launchers and errors
 #-----------------------------------------------------------------------------
 
 class LauncherError(Exception):
     pass
 
 
 class ProcessStateError(LauncherError):
     pass
 
 
 class UnknownStatus(LauncherError):
     pass
 
 
 class BaseLauncher(LoggingConfigurable):
     """An asbtraction for starting, stopping and signaling a process."""
 
     # In all of the launchers, the work_dir is where child processes will be
     # run. This will usually be the profile_dir, but may not be. any work_dir
     # passed into the __init__ method will override the config value.
     # This should not be used to set the work_dir for the actual engine
     # and controller. Instead, use their own config files or the
     # controller_args, engine_args attributes of the launchers to add
     # the work_dir option.
     work_dir = Unicode(u'.')
     loop = Instance('zmq.eventloop.ioloop.IOLoop')
 
     start_data = Any()
     stop_data = Any()
 
     def _loop_default(self):
         return ioloop.IOLoop.instance()
 
     def __init__(self, work_dir=u'.', config=None, **kwargs):
         super(BaseLauncher, self).__init__(work_dir=work_dir, config=config, **kwargs)
         self.state = 'before' # can be before, running, after
         self.stop_callbacks = []
         self.start_data = None
         self.stop_data = None
 
     @property
     def args(self):
         """A list of cmd and args that will be used to start the process.
 
         This is what is passed to :func:`spawnProcess` and the first element
         will be the process name.
         """
         return self.find_args()
 
     def find_args(self):
         """The ``.args`` property calls this to find the args list.
 
         Subcommand should implement this to construct the cmd and args.
         """
         raise NotImplementedError('find_args must be implemented in a subclass')
 
     @property
     def arg_str(self):
         """The string form of the program arguments."""
         return ' '.join(self.args)
 
     @property
     def running(self):
         """Am I running."""
         if self.state == 'running':
             return True
         else:
             return False
 
     def start(self):
         """Start the process."""
         raise NotImplementedError('start must be implemented in a subclass')
 
     def stop(self):
         """Stop the process and notify observers of stopping.
 
         This method will return None immediately.
         To observe the actual process stopping, see :meth:`on_stop`.
         """
         raise NotImplementedError('stop must be implemented in a subclass')
 
     def on_stop(self, f):
         """Register a callback to be called with this Launcher's stop_data
         when the process actually finishes.
         """
         if self.state=='after':
             return f(self.stop_data)
         else:
             self.stop_callbacks.append(f)
 
     def notify_start(self, data):
         """Call this to trigger startup actions.
 
         This logs the process startup and sets the state to 'running'.  It is
         a pass-through so it can be used as a callback.
         """
 
         self.log.debug('Process %r started: %r', self.args[0], data)
         self.start_data = data
         self.state = 'running'
         return data
 
     def notify_stop(self, data):
         """Call this to trigger process stop actions.
 
         This logs the process stopping and sets the state to 'after'. Call
         this to trigger callbacks registered via :meth:`on_stop`."""
 
         self.log.debug('Process %r stopped: %r', self.args[0], data)
         self.stop_data = data
         self.state = 'after'
         for i in range(len(self.stop_callbacks)):
             d = self.stop_callbacks.pop()
             d(data)
         return data
 
     def signal(self, sig):
         """Signal the process.
 
         Parameters
         ----------
         sig : str or int
             'KILL', 'INT', etc., or any signal number
         """
         raise NotImplementedError('signal must be implemented in a subclass')
 
 class ClusterAppMixin(HasTraits):
     """MixIn for cluster args as traits"""
     profile_dir=Unicode('')
     cluster_id=Unicode('')
 
     @property
     def cluster_args(self):
         return ['--profile-dir', self.profile_dir, '--cluster-id', self.cluster_id]
 
 class ControllerMixin(ClusterAppMixin):
     controller_cmd = List(ipcontroller_cmd_argv, config=True,
         help="""Popen command to launch ipcontroller.""")
     # Command line arguments to ipcontroller.
     controller_args = List(['--log-to-file','--log-level=%i' % logging.INFO], config=True,
         help="""command-line args to pass to ipcontroller""")
 
 class EngineMixin(ClusterAppMixin):
     engine_cmd = List(ipengine_cmd_argv, config=True,
         help="""command to launch the Engine.""")
     # Command line arguments for ipengine.
     engine_args = List(['--log-to-file','--log-level=%i' % logging.INFO], config=True,
         help="command-line arguments to pass to ipengine"
     )
 
 
 #-----------------------------------------------------------------------------
 # Local process launchers
 #-----------------------------------------------------------------------------
 
 
 class LocalProcessLauncher(BaseLauncher):
     """Start and stop an external process in an asynchronous manner.
 
     This will launch the external process with a working directory of
     ``self.work_dir``.
     """
 
     # This is used to to construct self.args, which is passed to
     # spawnProcess.
     cmd_and_args = List([])
     poll_frequency = Integer(100) # in ms
 
     def __init__(self, work_dir=u'.', config=None, **kwargs):
         super(LocalProcessLauncher, self).__init__(
             work_dir=work_dir, config=config, **kwargs
         )
         self.process = None
         self.poller = None
 
     def find_args(self):
         return self.cmd_and_args
 
     def start(self):
         self.log.debug("Starting %s: %r", self.__class__.__name__, self.args)
         if self.state == 'before':
             self.process = Popen(self.args,
                 stdout=PIPE,stderr=PIPE,stdin=PIPE,
                 env=os.environ,
                 cwd=self.work_dir
             )
             if WINDOWS:
                 self.stdout = forward_read_events(self.process.stdout)
                 self.stderr = forward_read_events(self.process.stderr)
             else:
                 self.stdout = self.process.stdout.fileno()
                 self.stderr = self.process.stderr.fileno()
             self.loop.add_handler(self.stdout, self.handle_stdout, self.loop.READ)
             self.loop.add_handler(self.stderr, self.handle_stderr, self.loop.READ)
             self.poller = ioloop.PeriodicCallback(self.poll, self.poll_frequency, self.loop)
             self.poller.start()
             self.notify_start(self.process.pid)
         else:
             s = 'The process was already started and has state: %r' % self.state
             raise ProcessStateError(s)
 
     def stop(self):
         return self.interrupt_then_kill()
 
     def signal(self, sig):
         if self.state == 'running':
             if WINDOWS and sig != SIGINT:
                 # use Windows tree-kill for better child cleanup
                 check_output(['taskkill', '-pid', str(self.process.pid), '-t', '-f'])
             else:
                 self.process.send_signal(sig)
 
     def interrupt_then_kill(self, delay=2.0):
         """Send INT, wait a delay and then send KILL."""
         try:
             self.signal(SIGINT)
         except Exception:
             self.log.debug("interrupt failed")
             pass
         self.killer  = ioloop.DelayedCallback(lambda : self.signal(SIGKILL), delay*1000, self.loop)
         self.killer.start()
 
     # callbacks, etc:
 
     def handle_stdout(self, fd, events):
         if WINDOWS:
             line = self.stdout.recv()
         else:
             line = self.process.stdout.readline()
         # a stopped process will be readable but return empty strings
         if line:
             self.log.debug(line[:-1])
         else:
             self.poll()
 
     def handle_stderr(self, fd, events):
         if WINDOWS:
             line = self.stderr.recv()
         else:
             line = self.process.stderr.readline()
         # a stopped process will be readable but return empty strings
         if line:
             self.log.debug(line[:-1])
         else:
             self.poll()
 
     def poll(self):
         status = self.process.poll()
         if status is not None:
             self.poller.stop()
             self.loop.remove_handler(self.stdout)
             self.loop.remove_handler(self.stderr)
             self.notify_stop(dict(exit_code=status, pid=self.process.pid))
         return status
 
 class LocalControllerLauncher(LocalProcessLauncher, ControllerMixin):
     """Launch a controller as a regular external process."""
 
     def find_args(self):
         return self.controller_cmd + self.cluster_args + self.controller_args
 
     def start(self):
         """Start the controller by profile_dir."""
         return super(LocalControllerLauncher, self).start()
 
 
 class LocalEngineLauncher(LocalProcessLauncher, EngineMixin):
     """Launch a single engine as a regular externall process."""
 
     def find_args(self):
         return self.engine_cmd + self.cluster_args + self.engine_args
 
 
 class LocalEngineSetLauncher(LocalEngineLauncher):
     """Launch a set of engines as regular external processes."""
 
     delay = CFloat(0.1, config=True,
         help="""delay (in seconds) between starting each engine after the first.
         This can help force the engines to get their ids in order, or limit
         process flood when starting many engines."""
     )
 
     # launcher class
     launcher_class = LocalEngineLauncher
 
     launchers = Dict()
     stop_data = Dict()
 
     def __init__(self, work_dir=u'.', config=None, **kwargs):
         super(LocalEngineSetLauncher, self).__init__(
             work_dir=work_dir, config=config, **kwargs
         )
         self.stop_data = {}
 
     def start(self, n):
         """Start n engines by profile or profile_dir."""
         dlist = []
         for i in range(n):
             if i > 0:
                 time.sleep(self.delay)
             el = self.launcher_class(work_dir=self.work_dir, parent=self, log=self.log,
                                     profile_dir=self.profile_dir, cluster_id=self.cluster_id,
             )
 
             # Copy the engine args over to each engine launcher.
             el.engine_cmd = copy.deepcopy(self.engine_cmd)
             el.engine_args = copy.deepcopy(self.engine_args)
             el.on_stop(self._notice_engine_stopped)
             d = el.start()
             self.launchers[i] = el
             dlist.append(d)
         self.notify_start(dlist)
         return dlist
 
     def find_args(self):
         return ['engine set']
 
     def signal(self, sig):
         dlist = []
         for el in itervalues(self.launchers):
             d = el.signal(sig)
             dlist.append(d)
         return dlist
 
     def interrupt_then_kill(self, delay=1.0):
         dlist = []
         for el in itervalues(self.launchers):
             d = el.interrupt_then_kill(delay)
             dlist.append(d)
         return dlist
 
     def stop(self):
         return self.interrupt_then_kill()
 
     def _notice_engine_stopped(self, data):
         pid = data['pid']
         for idx,el in iteritems(self.launchers):
             if el.process.pid == pid:
                 break
         self.launchers.pop(idx)
         self.stop_data[idx] = data
         if not self.launchers:
             self.notify_stop(self.stop_data)
 
 
 #-----------------------------------------------------------------------------
 # MPI launchers
 #-----------------------------------------------------------------------------
 
 
 class MPILauncher(LocalProcessLauncher):
     """Launch an external process using mpiexec."""
 
     mpi_cmd = List(['mpiexec'], config=True,
         help="The mpiexec command to use in starting the process."
     )
     mpi_args = List([], config=True,
         help="The command line arguments to pass to mpiexec."
     )
     program = List(['date'],
         help="The program to start via mpiexec.")
     program_args = List([],
         help="The command line argument to the program."
     )
     n = Integer(1)
     
     def __init__(self, *args, **kwargs):
         # deprecation for old MPIExec names:
         config = kwargs.get('config', {})
         for oldname in ('MPIExecLauncher', 'MPIExecControllerLauncher', 'MPIExecEngineSetLauncher'):
             deprecated = config.get(oldname)
             if deprecated:
                 newname = oldname.replace('MPIExec', 'MPI')
                 config[newname].update(deprecated)
                 self.log.warn("WARNING: %s name has been deprecated, use %s", oldname, newname)
 
         super(MPILauncher, self).__init__(*args, **kwargs)
 
     def find_args(self):
         """Build self.args using all the fields."""
         return self.mpi_cmd + ['-n', str(self.n)] + self.mpi_args + \
                self.program + self.program_args
 
     def start(self, n):
         """Start n instances of the program using mpiexec."""
         self.n = n
         return super(MPILauncher, self).start()
 
 
 class MPIControllerLauncher(MPILauncher, ControllerMixin):
     """Launch a controller using mpiexec."""
 
     # alias back to *non-configurable* program[_args] for use in find_args()
     # this way all Controller/EngineSetLaunchers have the same form, rather
     # than *some* having `program_args` and others `controller_args`
     @property
     def program(self):
         return self.controller_cmd
 
     @property
     def program_args(self):
         return self.cluster_args + self.controller_args
 
     def start(self):
         """Start the controller by profile_dir."""
         return super(MPIControllerLauncher, self).start(1)
 
 
 class MPIEngineSetLauncher(MPILauncher, EngineMixin):
     """Launch engines using mpiexec"""
 
     # alias back to *non-configurable* program[_args] for use in find_args()
     # this way all Controller/EngineSetLaunchers have the same form, rather
     # than *some* having `program_args` and others `controller_args`
     @property
     def program(self):
         return self.engine_cmd
 
     @property
     def program_args(self):
         return self.cluster_args + self.engine_args
 
     def start(self, n):
         """Start n engines by profile or profile_dir."""
         self.n = n
         return super(MPIEngineSetLauncher, self).start(n)
 
 # deprecated MPIExec names
 class DeprecatedMPILauncher(object):
     def warn(self):
         oldname = self.__class__.__name__
         newname = oldname.replace('MPIExec', 'MPI')
         self.log.warn("WARNING: %s name is deprecated, use %s", oldname, newname)
     
 class MPIExecLauncher(MPILauncher, DeprecatedMPILauncher):
     """Deprecated, use MPILauncher"""
     def __init__(self, *args, **kwargs):
         super(MPIExecLauncher, self).__init__(*args, **kwargs)
         self.warn()
 
 class MPIExecControllerLauncher(MPIControllerLauncher, DeprecatedMPILauncher):
     """Deprecated, use MPIControllerLauncher"""
     def __init__(self, *args, **kwargs):
         super(MPIExecControllerLauncher, self).__init__(*args, **kwargs)
         self.warn()
 
 class MPIExecEngineSetLauncher(MPIEngineSetLauncher, DeprecatedMPILauncher):
     """Deprecated, use MPIEngineSetLauncher"""
     def __init__(self, *args, **kwargs):
         super(MPIExecEngineSetLauncher, self).__init__(*args, **kwargs)
         self.warn()
 
 
 #-----------------------------------------------------------------------------
 # SSH launchers
 #-----------------------------------------------------------------------------
 
 # TODO: Get SSH Launcher back to level of sshx in 0.10.2
 
 class SSHLauncher(LocalProcessLauncher):
     """A minimal launcher for ssh.
 
     To be useful this will probably have to be extended to use the ``sshx``
     idea for environment variables.  There could be other things this needs
     as well.
     """
 
     ssh_cmd = List(['ssh'], config=True,
         help="command for starting ssh")
     ssh_args = List(['-tt'], config=True,
         help="args to pass to ssh")
     scp_cmd = List(['scp'], config=True,
         help="command for sending files")
     program = List(['date'],
         help="Program to launch via ssh")
     program_args = List([],
         help="args to pass to remote program")
     hostname = Unicode('', config=True,
         help="hostname on which to launch the program")
     user = Unicode('', config=True,
         help="username for ssh")
     location = Unicode('', config=True,
         help="user@hostname location for ssh in one setting")
     to_fetch = List([], config=True,
         help="List of (remote, local) files to fetch after starting")
     to_send = List([], config=True,
         help="List of (local, remote) files to send before starting")
 
     def _hostname_changed(self, name, old, new):
         if self.user:
             self.location = u'%s@%s' % (self.user, new)
         else:
             self.location = new
 
     def _user_changed(self, name, old, new):
         self.location = u'%s@%s' % (new, self.hostname)
 
     def find_args(self):
         return self.ssh_cmd + self.ssh_args + [self.location] + \
                list(map(pipes.quote, self.program + self.program_args))
     
     def _send_file(self, local, remote):
         """send a single file"""
         full_remote = "%s:%s" % (self.location, remote)
         for i in range(10):
             if not os.path.exists(local):
                 self.log.debug("waiting for %s" % local)
                 time.sleep(1)
             else:
                 break
         remote_dir = os.path.dirname(remote)
         self.log.info("ensuring remote %s:%s/ exists", self.location, remote_dir)
         check_output(self.ssh_cmd + self.ssh_args + \
             [self.location, 'mkdir', '-p', '--', remote_dir]
         )
         self.log.info("sending %s to %s", local, full_remote)
         check_output(self.scp_cmd + [local, full_remote])
     
     def send_files(self):
         """send our files (called before start)"""
         if not self.to_send:
             return
         for local_file, remote_file in self.to_send:
             self._send_file(local_file, remote_file)
 
     def _fetch_file(self, remote, local):
         """fetch a single file"""
         full_remote = "%s:%s" % (self.location, remote)
         self.log.info("fetching %s from %s", local, full_remote)
         for i in range(10):
             # wait up to 10s for remote file to exist
             check = check_output(self.ssh_cmd + self.ssh_args + \
                 [self.location, 'test -e', remote, "&& echo 'yes' || echo 'no'"])
             check = check.decode(DEFAULT_ENCODING, 'replace').strip()
             if check == u'no':
                 time.sleep(1)
             elif check == u'yes':
                 break
         local_dir = os.path.dirname(local)
-        if not os.path.exists(local_dir):
-            os.makedirs(local_dir, 775)
+        ensure_dir_exists(local_dir, 775)
         check_output(self.scp_cmd + [full_remote, local])
     
     def fetch_files(self):
         """fetch remote files (called after start)"""
         if not self.to_fetch:
             return
         for remote_file, local_file in self.to_fetch:
             self._fetch_file(remote_file, local_file)
 
     def start(self, hostname=None, user=None):
         if hostname is not None:
             self.hostname = hostname
         if user is not None:
             self.user = user
         
         self.send_files()
         super(SSHLauncher, self).start()
         self.fetch_files()
 
     def signal(self, sig):
         if self.state == 'running':
             # send escaped ssh connection-closer
             self.process.stdin.write('~.')
             self.process.stdin.flush()
 
 class SSHClusterLauncher(SSHLauncher, ClusterAppMixin):
     
     remote_profile_dir = Unicode('', config=True,
         help="""The remote profile_dir to use.  
         
         If not specified, use calling profile, stripping out possible leading homedir.
         """)
     
     def _profile_dir_changed(self, name, old, new):
         if not self.remote_profile_dir:
             # trigger remote_profile_dir_default logic again,
             # in case it was already triggered before profile_dir was set
             self.remote_profile_dir = self._strip_home(new)
     
     @staticmethod
     def _strip_home(path):
         """turns /home/you/.ipython/profile_foo into .ipython/profile_foo"""
         home = get_home_dir()
         if not home.endswith('/'):
             home = home+'/'
         
         if path.startswith(home):
             return path[len(home):]
         else:
             return path
 
     def _remote_profile_dir_default(self):
         return self._strip_home(self.profile_dir)
     
     def _cluster_id_changed(self, name, old, new):
         if new:
             raise ValueError("cluster id not supported by SSH launchers")
     
     @property
     def cluster_args(self):
         return ['--profile-dir', self.remote_profile_dir]
 
 class SSHControllerLauncher(SSHClusterLauncher, ControllerMixin):
 
     # alias back to *non-configurable* program[_args] for use in find_args()
     # this way all Controller/EngineSetLaunchers have the same form, rather
     # than *some* having `program_args` and others `controller_args`
 
     def _controller_cmd_default(self):
         return ['ipcontroller']
     
     @property
     def program(self):
         return self.controller_cmd
     
     @property
     def program_args(self):
         return self.cluster_args + self.controller_args
 
     def _to_fetch_default(self):
         return [
             (os.path.join(self.remote_profile_dir, 'security', cf),
              os.path.join(self.profile_dir, 'security', cf),)
             for cf in ('ipcontroller-client.json', 'ipcontroller-engine.json')
         ]
 
 class SSHEngineLauncher(SSHClusterLauncher, EngineMixin):
 
     # alias back to *non-configurable* program[_args] for use in find_args()
     # this way all Controller/EngineSetLaunchers have the same form, rather
     # than *some* having `program_args` and others `controller_args`
     
     def _engine_cmd_default(self):
         return ['ipengine']
     
     @property
     def program(self):
         return self.engine_cmd
 
     @property
     def program_args(self):
         return self.cluster_args + self.engine_args
     
     def _to_send_default(self):
         return [
             (os.path.join(self.profile_dir, 'security', cf), 
              os.path.join(self.remote_profile_dir, 'security', cf))
             for cf in ('ipcontroller-client.json', 'ipcontroller-engine.json')
         ]
 
 
 class SSHEngineSetLauncher(LocalEngineSetLauncher):
     launcher_class = SSHEngineLauncher
     engines = Dict(config=True,
         help="""dict of engines to launch.  This is a dict by hostname of ints,
         corresponding to the number of engines to start on that host.""")
     
     def _engine_cmd_default(self):
         return ['ipengine']
     
     @property
     def engine_count(self):
         """determine engine count from `engines` dict"""
         count = 0
         for n in itervalues(self.engines):
             if isinstance(n, (tuple,list)):
                 n,args = n
             count += n
         return count
     
     def start(self, n):
         """Start engines by profile or profile_dir.
         `n` is ignored, and the `engines` config property is used instead.
         """
 
         dlist = []
         for host, n in iteritems(self.engines):
             if isinstance(n, (tuple, list)):
                 n, args = n
             else:
                 args = copy.deepcopy(self.engine_args)
 
             if '@' in host:
                 user,host = host.split('@',1)
             else:
                 user=None
             for i in range(n):
                 if i > 0:
                     time.sleep(self.delay)
                 el = self.launcher_class(work_dir=self.work_dir, parent=self, log=self.log,
                                         profile_dir=self.profile_dir, cluster_id=self.cluster_id,
                 )
                 if i > 0:
                     # only send files for the first engine on each host
                     el.to_send = []
 
                 # Copy the engine args over to each engine launcher.
                 el.engine_cmd = self.engine_cmd
                 el.engine_args = args
                 el.on_stop(self._notice_engine_stopped)
                 d = el.start(user=user, hostname=host)
                 self.launchers[ "%s/%i" % (host,i) ] = el
                 dlist.append(d)
         self.notify_start(dlist)
         return dlist
 
 
 class SSHProxyEngineSetLauncher(SSHClusterLauncher):
     """Launcher for calling
     `ipcluster engines` on a remote machine.
     
     Requires that remote profile is already configured.
     """
     
     n = Integer()
     ipcluster_cmd = List(['ipcluster'], config=True)
     
     @property
     def program(self):
         return self.ipcluster_cmd + ['engines']
     
     @property
     def program_args(self):
         return ['-n', str(self.n), '--profile-dir', self.remote_profile_dir]
     
     def _to_send_default(self):
         return [
             (os.path.join(self.profile_dir, 'security', cf), 
              os.path.join(self.remote_profile_dir, 'security', cf))
             for cf in ('ipcontroller-client.json', 'ipcontroller-engine.json')
     ]
     
     def start(self, n):
         self.n = n
         super(SSHProxyEngineSetLauncher, self).start()
 
 
 #-----------------------------------------------------------------------------
 # Windows HPC Server 2008 scheduler launchers
 #-----------------------------------------------------------------------------
 
 
 # This is only used on Windows.
 def find_job_cmd():
     if WINDOWS:
         try:
             return find_cmd('job')
         except (FindCmdError, ImportError):
             # ImportError will be raised if win32api is not installed
             return 'job'
     else:
         return 'job'
 
 
 class WindowsHPCLauncher(BaseLauncher):
 
     job_id_regexp = CRegExp(r'\d+', config=True,
         help="""A regular expression used to get the job id from the output of the
         submit_command. """
         )
     job_file_name = Unicode(u'ipython_job.xml', config=True,
         help="The filename of the instantiated job script.")
     # The full path to the instantiated job script. This gets made dynamically
     # by combining the work_dir with the job_file_name.
     job_file = Unicode(u'')
     scheduler = Unicode('', config=True,
         help="The hostname of the scheduler to submit the job to.")
     job_cmd = Unicode(find_job_cmd(), config=True,
         help="The command for submitting jobs.")
 
     def __init__(self, work_dir=u'.', config=None, **kwargs):
         super(WindowsHPCLauncher, self).__init__(
             work_dir=work_dir, config=config, **kwargs
         )
 
     @property
     def job_file(self):
         return os.path.join(self.work_dir, self.job_file_name)
 
     def write_job_file(self, n):
         raise NotImplementedError("Implement write_job_file in a subclass.")
 
     def find_args(self):
         return [u'job.exe']
 
     def parse_job_id(self, output):
         """Take the output of the submit command and return the job id."""
         m = self.job_id_regexp.search(output)
         if m is not None:
             job_id = m.group()
         else:
             raise LauncherError("Job id couldn't be determined: %s" % output)
         self.job_id = job_id
         self.log.info('Job started with id: %r', job_id)
         return job_id
 
     def start(self, n):
         """Start n copies of the process using the Win HPC job scheduler."""
         self.write_job_file(n)
         args = [
             'submit',
             '/jobfile:%s' % self.job_file,
             '/scheduler:%s' % self.scheduler
         ]
         self.log.debug("Starting Win HPC Job: %s" % (self.job_cmd + ' ' + ' '.join(args),))
 
         output = check_output([self.job_cmd]+args,
             env=os.environ,
             cwd=self.work_dir,
             stderr=STDOUT
         )
         output = output.decode(DEFAULT_ENCODING, 'replace')
         job_id = self.parse_job_id(output)
         self.notify_start(job_id)
         return job_id
 
     def stop(self):
         args = [
             'cancel',
             self.job_id,
             '/scheduler:%s' % self.scheduler
         ]
         self.log.info("Stopping Win HPC Job: %s" % (self.job_cmd + ' ' + ' '.join(args),))
         try:
             output = check_output([self.job_cmd]+args,
                 env=os.environ,
                 cwd=self.work_dir,
                 stderr=STDOUT
             )
             output = output.decode(DEFAULT_ENCODING, 'replace')
         except:
             output = u'The job already appears to be stopped: %r' % self.job_id
         self.notify_stop(dict(job_id=self.job_id, output=output))  # Pass the output of the kill cmd
         return output
 
 
 class WindowsHPCControllerLauncher(WindowsHPCLauncher, ClusterAppMixin):
 
     job_file_name = Unicode(u'ipcontroller_job.xml', config=True,
         help="WinHPC xml job file.")
     controller_args = List([], config=False,
         help="extra args to pass to ipcontroller")
 
     def write_job_file(self, n):
         job = IPControllerJob(parent=self)
 
         t = IPControllerTask(parent=self)
         # The tasks work directory is *not* the actual work directory of
         # the controller. It is used as the base path for the stdout/stderr
         # files that the scheduler redirects to.
         t.work_directory = self.profile_dir
         # Add the profile_dir and from self.start().
         t.controller_args.extend(self.cluster_args)
         t.controller_args.extend(self.controller_args)
         job.add_task(t)
 
         self.log.debug("Writing job description file: %s", self.job_file)
         job.write(self.job_file)
 
     @property
     def job_file(self):
         return os.path.join(self.profile_dir, self.job_file_name)
 
     def start(self):
         """Start the controller by profile_dir."""
         return super(WindowsHPCControllerLauncher, self).start(1)
 
 
 class WindowsHPCEngineSetLauncher(WindowsHPCLauncher, ClusterAppMixin):
 
     job_file_name = Unicode(u'ipengineset_job.xml', config=True,
         help="jobfile for ipengines job")
     engine_args = List([], config=False,
         help="extra args to pas to ipengine")
 
     def write_job_file(self, n):
         job = IPEngineSetJob(parent=self)
 
         for i in range(n):
             t = IPEngineTask(parent=self)
             # The tasks work directory is *not* the actual work directory of
             # the engine. It is used as the base path for the stdout/stderr
             # files that the scheduler redirects to.
             t.work_directory = self.profile_dir
             # Add the profile_dir and from self.start().
             t.engine_args.extend(self.cluster_args)
             t.engine_args.extend(self.engine_args)
             job.add_task(t)
 
         self.log.debug("Writing job description file: %s", self.job_file)
         job.write(self.job_file)
 
     @property
     def job_file(self):
         return os.path.join(self.profile_dir, self.job_file_name)
 
     def start(self, n):
         """Start the controller by profile_dir."""
         return super(WindowsHPCEngineSetLauncher, self).start(n)
 
 
 #-----------------------------------------------------------------------------
 # Batch (PBS) system launchers
 #-----------------------------------------------------------------------------
 
 class BatchClusterAppMixin(ClusterAppMixin):
     """ClusterApp mixin that updates the self.context dict, rather than cl-args."""
     def _profile_dir_changed(self, name, old, new):
         self.context[name] = new
     _cluster_id_changed = _profile_dir_changed
 
     def _profile_dir_default(self):
         self.context['profile_dir'] = ''
         return ''
     def _cluster_id_default(self):
         self.context['cluster_id'] = ''
         return ''
 
 
 class BatchSystemLauncher(BaseLauncher):
     """Launch an external process using a batch system.
 
     This class is designed to work with UNIX batch systems like PBS, LSF,
     GridEngine, etc.  The overall model is that there are different commands
     like qsub, qdel, etc. that handle the starting and stopping of the process.
 
     This class also has the notion of a batch script. The ``batch_template``
     attribute can be set to a string that is a template for the batch script.
     This template is instantiated using string formatting. Thus the template can
     use {n} fot the number of instances. Subclasses can add additional variables
     to the template dict.
     """
 
     # Subclasses must fill these in.  See PBSEngineSet
     submit_command = List([''], config=True,
         help="The name of the command line program used to submit jobs.")
     delete_command = List([''], config=True,
         help="The name of the command line program used to delete jobs.")
     job_id_regexp = CRegExp('', config=True,
         help="""A regular expression used to get the job id from the output of the
         submit_command.""")
     job_id_regexp_group = Integer(0, config=True,
         help="""The group we wish to match in job_id_regexp (0 to match all)""")
     batch_template = Unicode('', config=True,
         help="The string that is the batch script template itself.")
     batch_template_file = Unicode(u'', config=True,
         help="The file that contains the batch template.")
     batch_file_name = Unicode(u'batch_script', config=True,
         help="The filename of the instantiated batch script.")
     queue = Unicode(u'', config=True,
         help="The PBS Queue.")
 
     def _queue_changed(self, name, old, new):
         self.context[name] = new
 
     n = Integer(1)
     _n_changed = _queue_changed
 
     # not configurable, override in subclasses
     # PBS Job Array regex
     job_array_regexp = CRegExp('')
     job_array_template = Unicode('')
     # PBS Queue regex
     queue_regexp = CRegExp('')
     queue_template = Unicode('')
     # The default batch template, override in subclasses
     default_template = Unicode('')
     # The full path to the instantiated batch script.
     batch_file = Unicode(u'')
     # the format dict used with batch_template:
     context = Dict()
 
     def _context_default(self):
         """load the default context with the default values for the basic keys
 
         because the _trait_changed methods only load the context if they
         are set to something other than the default value.
         """
         return dict(n=1, queue=u'', profile_dir=u'', cluster_id=u'')
     
     # the Formatter instance for rendering the templates:
     formatter = Instance(EvalFormatter, (), {})
 
     def find_args(self):
         return self.submit_command + [self.batch_file]
 
     def __init__(self, work_dir=u'.', config=None, **kwargs):
         super(BatchSystemLauncher, self).__init__(
             work_dir=work_dir, config=config, **kwargs
         )
         self.batch_file = os.path.join(self.work_dir, self.batch_file_name)
 
     def parse_job_id(self, output):
         """Take the output of the submit command and return the job id."""
         m = self.job_id_regexp.search(output)
         if m is not None:
             job_id = m.group(self.job_id_regexp_group)
         else:
             raise LauncherError("Job id couldn't be determined: %s" % output)
         self.job_id = job_id
         self.log.info('Job submitted with job id: %r', job_id)
         return job_id
 
     def write_batch_script(self, n):
         """Instantiate and write the batch script to the work_dir."""
         self.n = n
         # first priority is batch_template if set
         if self.batch_template_file and not self.batch_template:
             # second priority is batch_template_file
             with open(self.batch_template_file) as f:
                 self.batch_template = f.read()
         if not self.batch_template:
             # third (last) priority is default_template
             self.batch_template = self.default_template
             # add jobarray or queue lines to user-specified template
             # note that this is *only* when user did not specify a template.
             self._insert_queue_in_script()
             self._insert_job_array_in_script()
         script_as_string = self.formatter.format(self.batch_template, **self.context)
         self.log.debug('Writing batch script: %s', self.batch_file)
         with open(self.batch_file, 'w') as f:
             f.write(script_as_string)
         os.chmod(self.batch_file, stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR)
 
     def _insert_queue_in_script(self):
         """Inserts a queue if required into the batch script.
         """
         if self.queue and not self.queue_regexp.search(self.batch_template):
             self.log.debug("adding PBS queue settings to batch script")
             firstline, rest = self.batch_template.split('\n',1)
             self.batch_template = u'\n'.join([firstline, self.queue_template, rest])
 
     def _insert_job_array_in_script(self):
         """Inserts a job array if required into the batch script.
         """
         if not self.job_array_regexp.search(self.batch_template):
             self.log.debug("adding job array settings to batch script")
             firstline, rest = self.batch_template.split('\n',1)
             self.batch_template = u'\n'.join([firstline, self.job_array_template, rest])
 
     def start(self, n):
         """Start n copies of the process using a batch system."""
         self.log.debug("Starting %s: %r", self.__class__.__name__, self.args)
         # Here we save profile_dir in the context so they
         # can be used in the batch script template as {profile_dir}
         self.write_batch_script(n)
         output = check_output(self.args, env=os.environ)
         output = output.decode(DEFAULT_ENCODING, 'replace')
 
         job_id = self.parse_job_id(output)
         self.notify_start(job_id)
         return job_id
 
     def stop(self):
         try:
             p = Popen(self.delete_command+[self.job_id], env=os.environ,
                       stdout=PIPE, stderr=PIPE)
             out, err = p.communicate()
             output = out + err
         except:
             self.log.exception("Problem stopping cluster with command: %s" %
                                (self.delete_command + [self.job_id]))
             output = ""
         output = output.decode(DEFAULT_ENCODING, 'replace')
         self.notify_stop(dict(job_id=self.job_id, output=output)) # Pass the output of the kill cmd
         return output
 
 
 class PBSLauncher(BatchSystemLauncher):
     """A BatchSystemLauncher subclass for PBS."""
 
     submit_command = List(['qsub'], config=True,
         help="The PBS submit command ['qsub']")
     delete_command = List(['qdel'], config=True,
         help="The PBS delete command ['qsub']")
     job_id_regexp = CRegExp(r'\d+', config=True,
         help="Regular expresion for identifying the job ID [r'\d+']")
 
     batch_file = Unicode(u'')
     job_array_regexp = CRegExp('#PBS\W+-t\W+[\w\d\-\$]+')
     job_array_template = Unicode('#PBS -t 1-{n}')
     queue_regexp = CRegExp('#PBS\W+-q\W+\$?\w+')
     queue_template = Unicode('#PBS -q {queue}')
 
 
 class PBSControllerLauncher(PBSLauncher, BatchClusterAppMixin):
     """Launch a controller using PBS."""
 
     batch_file_name = Unicode(u'pbs_controller', config=True,
         help="batch file name for the controller job.")
     default_template= Unicode("""#!/bin/sh
 #PBS -V
 #PBS -N ipcontroller
 %s --log-to-file --profile-dir="{profile_dir}" --cluster-id="{cluster_id}"
 """%(' '.join(map(pipes.quote, ipcontroller_cmd_argv))))
 
     def start(self):
         """Start the controller by profile or profile_dir."""
         return super(PBSControllerLauncher, self).start(1)
 
 
 class PBSEngineSetLauncher(PBSLauncher, BatchClusterAppMixin):
     """Launch Engines using PBS"""
     batch_file_name = Unicode(u'pbs_engines', config=True,
         help="batch file name for the engine(s) job.")
     default_template= Unicode(u"""#!/bin/sh
 #PBS -V
 #PBS -N ipengine
 %s --profile-dir="{profile_dir}" --cluster-id="{cluster_id}"
 """%(' '.join(map(pipes.quote,ipengine_cmd_argv))))
 
 
 #SGE is very similar to PBS
 
 class SGELauncher(PBSLauncher):
     """Sun GridEngine is a PBS clone with slightly different syntax"""
     job_array_regexp = CRegExp('#\$\W+\-t')
     job_array_template = Unicode('#$ -t 1-{n}')
     queue_regexp = CRegExp('#\$\W+-q\W+\$?\w+')
     queue_template = Unicode('#$ -q {queue}')
 
 
 class SGEControllerLauncher(SGELauncher, BatchClusterAppMixin):
     """Launch a controller using SGE."""
 
     batch_file_name = Unicode(u'sge_controller', config=True,
         help="batch file name for the ipontroller job.")
     default_template= Unicode(u"""#$ -V
 #$ -S /bin/sh
 #$ -N ipcontroller
 %s --log-to-file --profile-dir="{profile_dir}" --cluster-id="{cluster_id}"
 """%(' '.join(map(pipes.quote, ipcontroller_cmd_argv))))
 
     def start(self):
         """Start the controller by profile or profile_dir."""
         return super(SGEControllerLauncher, self).start(1)
 
 
 class SGEEngineSetLauncher(SGELauncher, BatchClusterAppMixin):
     """Launch Engines with SGE"""
     batch_file_name = Unicode(u'sge_engines', config=True,
         help="batch file name for the engine(s) job.")
     default_template = Unicode("""#$ -V
 #$ -S /bin/sh
 #$ -N ipengine
 %s --profile-dir="{profile_dir}" --cluster-id="{cluster_id}"
 """%(' '.join(map(pipes.quote, ipengine_cmd_argv))))
 
 
 # LSF launchers
 
 class LSFLauncher(BatchSystemLauncher):
     """A BatchSystemLauncher subclass for LSF."""
 
     submit_command = List(['bsub'], config=True,
                           help="The PBS submit command ['bsub']")
     delete_command = List(['bkill'], config=True,
                           help="The PBS delete command ['bkill']")
     job_id_regexp = CRegExp(r'\d+', config=True,
                             help="Regular expresion for identifying the job ID [r'\d+']")
 
     batch_file = Unicode(u'')
     job_array_regexp = CRegExp('#BSUB[ \t]-J+\w+\[\d+-\d+\]')
     job_array_template = Unicode('#BSUB -J ipengine[1-{n}]')
     queue_regexp = CRegExp('#BSUB[ \t]+-q[ \t]+\w+')
     queue_template = Unicode('#BSUB -q {queue}')
 
     def start(self, n):
         """Start n copies of the process using LSF batch system.
         This cant inherit from the base class because bsub expects
         to be piped a shell script in order to honor the #BSUB directives :
         bsub < script
         """
         # Here we save profile_dir in the context so they
         # can be used in the batch script template as {profile_dir}
         self.write_batch_script(n)
         piped_cmd = self.args[0]+'<\"'+self.args[1]+'\"'
         self.log.debug("Starting %s: %s", self.__class__.__name__, piped_cmd)
         p = Popen(piped_cmd, shell=True,env=os.environ,stdout=PIPE)
         output,err = p.communicate()
         output = output.decode(DEFAULT_ENCODING, 'replace')
         job_id = self.parse_job_id(output)
         self.notify_start(job_id)
         return job_id
 
 
 class LSFControllerLauncher(LSFLauncher, BatchClusterAppMixin):
     """Launch a controller using LSF."""
 
     batch_file_name = Unicode(u'lsf_controller', config=True,
                               help="batch file name for the controller job.")
     default_template= Unicode("""#!/bin/sh
     #BSUB -J ipcontroller
     #BSUB -oo ipcontroller.o.%%J
     #BSUB -eo ipcontroller.e.%%J
     %s --log-to-file --profile-dir="{profile_dir}" --cluster-id="{cluster_id}"
     """%(' '.join(map(pipes.quote,ipcontroller_cmd_argv))))
 
     def start(self):
         """Start the controller by profile or profile_dir."""
         return super(LSFControllerLauncher, self).start(1)
 
 
 class LSFEngineSetLauncher(LSFLauncher, BatchClusterAppMixin):
     """Launch Engines using LSF"""
     batch_file_name = Unicode(u'lsf_engines', config=True,
                               help="batch file name for the engine(s) job.")
     default_template= Unicode(u"""#!/bin/sh
     #BSUB -oo ipengine.o.%%J
     #BSUB -eo ipengine.e.%%J
     %s --profile-dir="{profile_dir}" --cluster-id="{cluster_id}"
     """%(' '.join(map(pipes.quote, ipengine_cmd_argv))))
 
 
 
 class HTCondorLauncher(BatchSystemLauncher):
     """A BatchSystemLauncher subclass for HTCondor.
 
     HTCondor requires that we launch the ipengine/ipcontroller scripts rather
     that the python instance but otherwise is very similar to PBS.  This is because 
     HTCondor destroys sys.executable when launching remote processes - a launched 
     python process depends on sys.executable to effectively evaluate its
     module search paths. Without it, regardless of which python interpreter you launch
     you will get the to built in module search paths.
 
     We use the ip{cluster, engine, controller} scripts as our executable to circumvent 
     this - the mechanism of shebanged scripts means that the python binary will be 
     launched with argv[0] set to the *location of the ip{cluster, engine, controller} 
     scripts on the remote node*. This means you need to take care that:
 
     a. Your remote nodes have their paths configured correctly, with the ipengine and ipcontroller
        of the python environment you wish to execute code in having top precedence.
     b. This functionality is untested on Windows.
 
     If you need different behavior, consider making you own template.
     """
 
     submit_command = List(['condor_submit'], config=True,
         help="The HTCondor submit command ['condor_submit']")
     delete_command = List(['condor_rm'], config=True,
         help="The HTCondor delete command ['condor_rm']")
     job_id_regexp = CRegExp(r'(\d+)\.$', config=True,
         help="Regular expression for identifying the job ID [r'(\d+)\.$']")
     job_id_regexp_group = Integer(1, config=True,
         help="""The group we wish to match in job_id_regexp [1]""")
 
     job_array_regexp = CRegExp('queue\W+\$')
     job_array_template = Unicode('queue {n}')
 
 
     def _insert_job_array_in_script(self):
         """Inserts a job array if required into the batch script.
         """
         if not self.job_array_regexp.search(self.batch_template):
             self.log.debug("adding job array settings to batch script")
             #HTCondor requires that the job array goes at the bottom of the script
             self.batch_template = '\n'.join([self.batch_template,
                 self.job_array_template])
 
     def _insert_queue_in_script(self):
         """AFAIK, HTCondor doesn't have a concept of multiple queues that can be
         specified in the script.
         """
         pass
 
 
 class HTCondorControllerLauncher(HTCondorLauncher, BatchClusterAppMixin):
     """Launch a controller using HTCondor."""
 
     batch_file_name = Unicode(u'htcondor_controller', config=True,
                               help="batch file name for the controller job.")
     default_template = Unicode(r"""
 universe        = vanilla
 executable      = ipcontroller
 # by default we expect a shared file system
 transfer_executable = False
 arguments       = --log-to-file '--profile-dir={profile_dir}' --cluster-id='{cluster_id}'
 """)
 
     def start(self):
         """Start the controller by profile or profile_dir."""
         return super(HTCondorControllerLauncher, self).start(1)
 
 
 class HTCondorEngineSetLauncher(HTCondorLauncher, BatchClusterAppMixin):
     """Launch Engines using HTCondor"""
     batch_file_name = Unicode(u'htcondor_engines', config=True,
                               help="batch file name for the engine(s) job.")
     default_template = Unicode("""
 universe        = vanilla
 executable      = ipengine
 # by default we expect a shared file system
 transfer_executable = False
 arguments       = "--log-to-file '--profile-dir={profile_dir}' '--cluster-id={cluster_id}'"
 """)
 
 
 #-----------------------------------------------------------------------------
 # A launcher for ipcluster itself!
 #-----------------------------------------------------------------------------
 
 
 class IPClusterLauncher(LocalProcessLauncher):
     """Launch the ipcluster program in an external process."""
 
     ipcluster_cmd = List(ipcluster_cmd_argv, config=True,
         help="Popen command for ipcluster")
     ipcluster_args = List(
         ['--clean-logs=True', '--log-to-file', '--log-level=%i'%logging.INFO], config=True,
         help="Command line arguments to pass to ipcluster.")
     ipcluster_subcommand = Unicode('start')
     profile = Unicode('default')
     n = Integer(2)
 
     def find_args(self):
         return self.ipcluster_cmd + [self.ipcluster_subcommand] + \
             ['--n=%i'%self.n, '--profile=%s'%self.profile] + \
             self.ipcluster_args
 
     def start(self):
         return super(IPClusterLauncher, self).start()
 
 #-----------------------------------------------------------------------------
 # Collections of launchers
 #-----------------------------------------------------------------------------
 
 local_launchers = [
     LocalControllerLauncher,
     LocalEngineLauncher,
     LocalEngineSetLauncher,
 ]
 mpi_launchers = [
     MPILauncher,
     MPIControllerLauncher,
     MPIEngineSetLauncher,
 ]
 ssh_launchers = [
     SSHLauncher,
     SSHControllerLauncher,
     SSHEngineLauncher,
     SSHEngineSetLauncher,
     SSHProxyEngineSetLauncher,
 ]
 winhpc_launchers = [
     WindowsHPCLauncher,
     WindowsHPCControllerLauncher,
     WindowsHPCEngineSetLauncher,
 ]
 pbs_launchers = [
     PBSLauncher,
     PBSControllerLauncher,
     PBSEngineSetLauncher,
 ]
 sge_launchers = [
     SGELauncher,
     SGEControllerLauncher,
     SGEEngineSetLauncher,
 ]
 lsf_launchers = [
     LSFLauncher,
     LSFControllerLauncher,
     LSFEngineSetLauncher,
 ]
 htcondor_launchers = [
     HTCondorLauncher,
     HTCondorControllerLauncher,
     HTCondorEngineSetLauncher,
 ]
 all_launchers = local_launchers + mpi_launchers + ssh_launchers + winhpc_launchers\
                 + pbs_launchers + sge_launchers + lsf_launchers + htcondor_launchers

IPython/qt/console/rich_ipython_widget.py

@@ -1,343 +1,335 b''
-#-----------------------------------------------------------------------------
-# Copyright (c) 2010, IPython Development Team.
-#
+# Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
-#
-# The full license is in the file COPYING.txt, distributed with this software.
-#-----------------------------------------------------------------------------
 
-# Standard libary imports.
 from base64 import decodestring
 import os
 import re
 
-# System libary imports.
 from IPython.external.qt import QtCore, QtGui
 
-# Local imports
+from IPython.utils.path import ensure_dir_exists
 from IPython.utils.traitlets import Bool
 from IPython.qt.svg import save_svg, svg_to_clipboard, svg_to_image
 from .ipython_widget import IPythonWidget
 
 
 class RichIPythonWidget(IPythonWidget):
     """ An IPythonWidget that supports rich text, including lists, images, and
         tables. Note that raw performance will be reduced compared to the plain
         text version.
     """
 
     # RichIPythonWidget protected class variables.
     _payload_source_plot = 'IPython.kernel.zmq.pylab.backend_payload.add_plot_payload'
     _jpg_supported = Bool(False)
 
     # Used to determine whether a given html export attempt has already
     # displayed a warning about being unable to convert a png to svg.
     _svg_warning_displayed = False
 
     #---------------------------------------------------------------------------
     # 'object' interface
     #---------------------------------------------------------------------------
 
     def __init__(self, *args, **kw):
         """ Create a RichIPythonWidget.
         """
         kw['kind'] = 'rich'
         super(RichIPythonWidget, self).__init__(*args, **kw)
 
         # Configure the ConsoleWidget HTML exporter for our formats.
         self._html_exporter.image_tag = self._get_image_tag
 
         # Dictionary for resolving document resource names to SVG data.
         self._name_to_svg_map = {}
 
         # Do we support jpg ?
         # it seems that sometime jpg support is a plugin of QT, so try to assume
         # it is not always supported.
         _supported_format = map(str, QtGui.QImageReader.supportedImageFormats())
         self._jpg_supported = 'jpeg' in _supported_format
 
 
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' public interface overides
     #---------------------------------------------------------------------------
 
     def export_html(self):
         """ Shows a dialog to export HTML/XML in various formats.
 
         Overridden in order to reset the _svg_warning_displayed flag prior
         to the export running.
         """
         self._svg_warning_displayed = False
         super(RichIPythonWidget, self).export_html()
 
 
     #---------------------------------------------------------------------------
     # 'ConsoleWidget' protected interface
     #---------------------------------------------------------------------------
 
     def _context_menu_make(self, pos):
         """ Reimplemented to return a custom context menu for images.
         """
         format = self._control.cursorForPosition(pos).charFormat()
         name = format.stringProperty(QtGui.QTextFormat.ImageName)
         if name:
             menu = QtGui.QMenu()
 
             menu.addAction('Copy Image', lambda: self._copy_image(name))
             menu.addAction('Save Image As...', lambda: self._save_image(name))
             menu.addSeparator()
 
             svg = self._name_to_svg_map.get(name, None)
             if svg is not None:
                 menu.addSeparator()
                 menu.addAction('Copy SVG', lambda: svg_to_clipboard(svg))
                 menu.addAction('Save SVG As...',
                                lambda: save_svg(svg, self._control))
         else:
             menu = super(RichIPythonWidget, self)._context_menu_make(pos)
         return menu
 
     #---------------------------------------------------------------------------
     # 'BaseFrontendMixin' abstract interface
     #---------------------------------------------------------------------------
     def _pre_image_append(self, msg, prompt_number):
         """ Append the Out[] prompt  and make the output nicer
 
         Shared code for some the following if statement
         """
         self.log.debug("pyout: %s", msg.get('content', ''))
         self._append_plain_text(self.output_sep, True)
         self._append_html(self._make_out_prompt(prompt_number), True)
         self._append_plain_text('\n', True)
 
     def _handle_pyout(self, msg):
         """ Overridden to handle rich data types, like SVG.
         """
         if not self._hidden and self._is_from_this_session(msg):
             self.flush_clearoutput()
             content = msg['content']
             prompt_number = content.get('execution_count', 0)
             data = content['data']
             metadata = msg['content']['metadata']
             if 'image/svg+xml' in data:
                 self._pre_image_append(msg, prompt_number)
                 self._append_svg(data['image/svg+xml'], True)
                 self._append_html(self.output_sep2, True)
             elif 'image/png' in data:
                 self._pre_image_append(msg, prompt_number)
                 png = decodestring(data['image/png'].encode('ascii'))
                 self._append_png(png, True, metadata=metadata.get('image/png', None))
                 self._append_html(self.output_sep2, True)
             elif 'image/jpeg' in data and self._jpg_supported:
                 self._pre_image_append(msg, prompt_number)
                 jpg = decodestring(data['image/jpeg'].encode('ascii'))
                 self._append_jpg(jpg, True, metadata=metadata.get('image/jpeg', None))
                 self._append_html(self.output_sep2, True)
             else:
                 # Default back to the plain text representation.
                 return super(RichIPythonWidget, self)._handle_pyout(msg)
 
     def _handle_display_data(self, msg):
         """ Overridden to handle rich data types, like SVG.
         """
         if not self._hidden and self._is_from_this_session(msg):
             self.flush_clearoutput()
             source = msg['content']['source']
             data = msg['content']['data']
             metadata = msg['content']['metadata']
             # Try to use the svg or html representations.
             # FIXME: Is this the right ordering of things to try?
             if 'image/svg+xml' in data:
                 self.log.debug("display: %s", msg.get('content', ''))
                 svg = data['image/svg+xml']
                 self._append_svg(svg, True)
             elif 'image/png' in data:
                 self.log.debug("display: %s", msg.get('content', ''))
                 # PNG data is base64 encoded as it passes over the network
                 # in a JSON structure so we decode it.
                 png = decodestring(data['image/png'].encode('ascii'))
                 self._append_png(png, True, metadata=metadata.get('image/png', None))
             elif 'image/jpeg' in data and self._jpg_supported:
                 self.log.debug("display: %s", msg.get('content', ''))
                 jpg = decodestring(data['image/jpeg'].encode('ascii'))
                 self._append_jpg(jpg, True, metadata=metadata.get('image/jpeg', None))
             else:
                 # Default back to the plain text representation.
                 return super(RichIPythonWidget, self)._handle_display_data(msg)
 
     #---------------------------------------------------------------------------
     # 'RichIPythonWidget' protected interface
     #---------------------------------------------------------------------------
 
     def _append_jpg(self, jpg, before_prompt=False, metadata=None):
         """ Append raw JPG data to the widget."""
         self._append_custom(self._insert_jpg, jpg, before_prompt, metadata=metadata)
 
     def _append_png(self, png, before_prompt=False, metadata=None):
         """ Append raw PNG data to the widget.
         """
         self._append_custom(self._insert_png, png, before_prompt, metadata=metadata)
 
     def _append_svg(self, svg, before_prompt=False):
         """ Append raw SVG data to the widget.
         """
         self._append_custom(self._insert_svg, svg, before_prompt)
 
     def _add_image(self, image):
         """ Adds the specified QImage to the document and returns a
             QTextImageFormat that references it.
         """
         document = self._control.document()
         name = str(image.cacheKey())
         document.addResource(QtGui.QTextDocument.ImageResource,
                              QtCore.QUrl(name), image)
         format = QtGui.QTextImageFormat()
         format.setName(name)
         return format
 
     def _copy_image(self, name):
         """ Copies the ImageResource with 'name' to the clipboard.
         """
         image = self._get_image(name)
         QtGui.QApplication.clipboard().setImage(image)
 
     def _get_image(self, name):
         """ Returns the QImage stored as the ImageResource with 'name'.
         """
         document = self._control.document()
         image = document.resource(QtGui.QTextDocument.ImageResource,
                                   QtCore.QUrl(name))
         return image
 
     def _get_image_tag(self, match, path = None, format = "png"):
         """ Return (X)HTML mark-up for the image-tag given by match.
 
         Parameters
         ----------
         match : re.SRE_Match
             A match to an HTML image tag as exported by Qt, with
             match.group("Name") containing the matched image ID.
 
         path : string|None, optional [default None]
             If not None, specifies a path to which supporting files may be
             written (e.g., for linked images).  If None, all images are to be
             included inline.
 
         format : "png"|"svg"|"jpg", optional [default "png"]
             Format for returned or referenced images.
         """
         if format in ("png","jpg"):
             try:
                 image = self._get_image(match.group("name"))
             except KeyError:
                 return "<b>Couldn't find image %s</b>" % match.group("name")
 
             if path is not None:
-                if not os.path.exists(path):
-                    os.mkdir(path)
+                ensure_dir_exists(path)
                 relpath = os.path.basename(path)
                 if image.save("%s/qt_img%s.%s" % (path, match.group("name"), format),
                               "PNG"):
                     return '<img src="%s/qt_img%s.%s">' % (relpath,
                                                             match.group("name"),format)
                 else:
                     return "<b>Couldn't save image!</b>"
             else:
                 ba = QtCore.QByteArray()
                 buffer_ = QtCore.QBuffer(ba)
                 buffer_.open(QtCore.QIODevice.WriteOnly)
                 image.save(buffer_, format.upper())
                 buffer_.close()
                 return '<img src="data:image/%s;base64,\n%s\n" />' % (
                     format,re.sub(r'(.{60})',r'\1\n',str(ba.toBase64())))
 
         elif format == "svg":
             try:
                 svg = str(self._name_to_svg_map[match.group("name")])
             except KeyError:
                 if not self._svg_warning_displayed:
                     QtGui.QMessageBox.warning(self, 'Error converting PNG to SVG.',
                         'Cannot convert PNG images to SVG, export with PNG figures instead. '
                         'If you want to export matplotlib figures as SVG, add '
                         'to your ipython config:\n\n'
                         '\tc.InlineBackend.figure_format = \'svg\'\n\n'
                         'And regenerate the figures.',
                                               QtGui.QMessageBox.Ok)
                     self._svg_warning_displayed = True
                 return ("<b>Cannot convert  PNG images to SVG.</b>  "
                         "You must export this session with PNG images. "
                         "If you want to export matplotlib figures as SVG, add to your config "
                         "<span>c.InlineBackend.figure_format = 'svg'</span> "
                         "and regenerate the figures.")
 
             # Not currently checking path, because it's tricky to find a
             # cross-browser way to embed external SVG images (e.g., via
             # object or embed tags).
 
             # Chop stand-alone header from matplotlib SVG
             offset = svg.find("<svg")
             assert(offset > -1)
 
             return svg[offset:]
 
         else:
             return '<b>Unrecognized image format</b>'
 
     def _insert_jpg(self, cursor, jpg, metadata=None):
         """ Insert raw PNG data into the widget."""
         self._insert_img(cursor, jpg, 'jpg', metadata=metadata)
 
     def _insert_png(self, cursor, png, metadata=None):
         """ Insert raw PNG data into the widget.
         """
         self._insert_img(cursor, png, 'png', metadata=metadata)
 
     def _insert_img(self, cursor, img, fmt, metadata=None):
         """ insert a raw image, jpg or png """
         if metadata:
             width = metadata.get('width', None)
             height = metadata.get('height', None)
         else:
             width = height = None
         try:
             image = QtGui.QImage()
             image.loadFromData(img, fmt.upper())
             if width and height:
                 image = image.scaled(width, height, transformMode=QtCore.Qt.SmoothTransformation)
             elif width and not height:
                 image = image.scaledToWidth(width, transformMode=QtCore.Qt.SmoothTransformation)
             elif height and not width:
                 image = image.scaledToHeight(height, transformMode=QtCore.Qt.SmoothTransformation)
         except ValueError:
             self._insert_plain_text(cursor, 'Received invalid %s data.'%fmt)
         else:
             format = self._add_image(image)
             cursor.insertBlock()
             cursor.insertImage(format)
             cursor.insertBlock()
 
     def _insert_svg(self, cursor, svg):
         """ Insert raw SVG data into the widet.
         """
         try:
             image = svg_to_image(svg)
         except ValueError:
             self._insert_plain_text(cursor, 'Received invalid SVG data.')
         else:
             format = self._add_image(image)
             self._name_to_svg_map[format.name()] = svg
             cursor.insertBlock()
             cursor.insertImage(format)
             cursor.insertBlock()
 
     def _save_image(self, name, format='PNG'):
         """ Shows a save dialog for the ImageResource with 'name'.
         """
         dialog = QtGui.QFileDialog(self._control, 'Save Image')
         dialog.setAcceptMode(QtGui.QFileDialog.AcceptSave)
         dialog.setDefaultSuffix(format.lower())
         dialog.setNameFilter('%s file (*.%s)' % (format, format.lower()))
         if dialog.exec_():
             filename = dialog.selectedFiles()[0]
             image = self._get_image(name)
             image.save(filename, format)

IPython/utils/path.py

@@ -1,574 +1,580 b''
 # encoding: utf-8
 """
 Utilities for path handling.
 """
 
-#-----------------------------------------------------------------------------
-#  Copyright (C) 2008-2011  The IPython Development Team
-#
-#  Distributed under the terms of the BSD License.  The full license is in
-#  the file COPYING, distributed as part of this software.
-#-----------------------------------------------------------------------------
-
-#-----------------------------------------------------------------------------
-# Imports
-#-----------------------------------------------------------------------------
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
 
 import os
 import sys
 import errno
 import shutil
 import random
 import tempfile
 import warnings
 from hashlib import md5
 import glob
 
 import IPython
 from IPython.testing.skipdoctest import skip_doctest
 from IPython.utils.process import system
 from IPython.utils.importstring import import_item
 from IPython.utils import py3compat
 #-----------------------------------------------------------------------------
 # Code
 #-----------------------------------------------------------------------------
 
 fs_encoding = sys.getfilesystemencoding()
 
 def _get_long_path_name(path):
     """Dummy no-op."""
     return path
 
 def _writable_dir(path):
     """Whether `path` is a directory, to which the user has write access."""
     return os.path.isdir(path) and os.access(path, os.W_OK)
 
 if sys.platform == 'win32':
     @skip_doctest
     def _get_long_path_name(path):
         """Get a long path name (expand ~) on Windows using ctypes.
 
         Examples
         --------
 
         >>> get_long_path_name('c:\\docume~1')
         u'c:\\\\Documents and Settings'
 
         """
         try:
             import ctypes
         except ImportError:
             raise ImportError('you need to have ctypes installed for this to work')
         _GetLongPathName = ctypes.windll.kernel32.GetLongPathNameW
         _GetLongPathName.argtypes = [ctypes.c_wchar_p, ctypes.c_wchar_p,
             ctypes.c_uint ]
 
         buf = ctypes.create_unicode_buffer(260)
         rv = _GetLongPathName(path, buf, 260)
         if rv == 0 or rv > 260:
             return path
         else:
             return buf.value
 
 
 def get_long_path_name(path):
     """Expand a path into its long form.
 
     On Windows this expands any ~ in the paths. On other platforms, it is
     a null operation.
     """
     return _get_long_path_name(path)
 
 
 def unquote_filename(name, win32=(sys.platform=='win32')):
     """ On Windows, remove leading and trailing quotes from filenames.
     """
     if win32:
         if name.startswith(("'", '"')) and name.endswith(("'", '"')):
             name = name[1:-1]
     return name
 
 def compress_user(path):
     """Reverse of :func:`os.path.expanduser`
     """
     home = os.path.expanduser('~')
     if path.startswith(home):
         path =  "~" + path[len(home):]
     return path
 
 def get_py_filename(name, force_win32=None):
     """Return a valid python filename in the current directory.
 
     If the given name is not a file, it adds '.py' and searches again.
     Raises IOError with an informative message if the file isn't found.
 
     On Windows, apply Windows semantics to the filename. In particular, remove
     any quoting that has been applied to it. This option can be forced for
     testing purposes.
     """
 
     name = os.path.expanduser(name)
     if force_win32 is None:
         win32 = (sys.platform == 'win32')
     else:
         win32 = force_win32
     name = unquote_filename(name, win32=win32)
     if not os.path.isfile(name) and not name.endswith('.py'):
         name += '.py'
     if os.path.isfile(name):
         return name
     else:
         raise IOError('File `%r` not found.' % name)
 
 
 def filefind(filename, path_dirs=None):
     """Find a file by looking through a sequence of paths.
 
     This iterates through a sequence of paths looking for a file and returns
     the full, absolute path of the first occurence of the file.  If no set of
     path dirs is given, the filename is tested as is, after running through
     :func:`expandvars` and :func:`expanduser`.  Thus a simple call::
 
         filefind('myfile.txt')
 
     will find the file in the current working dir, but::
 
         filefind('~/myfile.txt')
 
     Will find the file in the users home directory.  This function does not
     automatically try any paths, such as the cwd or the user's home directory.
 
     Parameters
     ----------
     filename : str
         The filename to look for.
     path_dirs : str, None or sequence of str
         The sequence of paths to look for the file in.  If None, the filename
         need to be absolute or be in the cwd.  If a string, the string is
         put into a sequence and the searched.  If a sequence, walk through
         each element and join with ``filename``, calling :func:`expandvars`
         and :func:`expanduser` before testing for existence.
 
     Returns
     -------
     Raises :exc:`IOError` or returns absolute path to file.
     """
 
     # If paths are quoted, abspath gets confused, strip them...
     filename = filename.strip('"').strip("'")
     # If the input is an absolute path, just check it exists
     if os.path.isabs(filename) and os.path.isfile(filename):
         return filename
 
     if path_dirs is None:
         path_dirs = ("",)
     elif isinstance(path_dirs, py3compat.string_types):
         path_dirs = (path_dirs,)
 
     for path in path_dirs:
         if path == '.': path = py3compat.getcwd()
         testname = expand_path(os.path.join(path, filename))
         if os.path.isfile(testname):
             return os.path.abspath(testname)
 
     raise IOError("File %r does not exist in any of the search paths: %r" %
                   (filename, path_dirs) )
 
 
 class HomeDirError(Exception):
     pass
 
 
 def get_home_dir(require_writable=False):
     """Return the 'home' directory, as a unicode string.
 
     Uses os.path.expanduser('~'), and checks for writability.
     
     See stdlib docs for how this is determined.
     $HOME is first priority on *ALL* platforms.
     
     Parameters
     ----------
     
     require_writable : bool [default: False]
         if True:
             guarantees the return value is a writable directory, otherwise
             raises HomeDirError
         if False:
             The path is resolved, but it is not guaranteed to exist or be writable.
     """
 
     homedir = os.path.expanduser('~')
     # Next line will make things work even when /home/ is a symlink to
     # /usr/home as it is on FreeBSD, for example
     homedir = os.path.realpath(homedir)
     
     if not _writable_dir(homedir) and os.name == 'nt':
         # expanduser failed, use the registry to get the 'My Documents' folder.
         try:
             try:
                 import winreg as wreg  # Py 3
             except ImportError:
                 import _winreg as wreg  # Py 2
             key = wreg.OpenKey(
                 wreg.HKEY_CURRENT_USER,
                 "Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders"
             )
             homedir = wreg.QueryValueEx(key,'Personal')[0]
             key.Close()
         except:
             pass
     
     if (not require_writable) or _writable_dir(homedir):
         return py3compat.cast_unicode(homedir, fs_encoding)
     else:
         raise HomeDirError('%s is not a writable dir, '
                 'set $HOME environment variable to override' % homedir)
 
 def get_xdg_dir():
     """Return the XDG_CONFIG_HOME, if it is defined and exists, else None.
 
     This is only for non-OS X posix (Linux,Unix,etc.) systems.
     """
 
     env = os.environ
 
     if os.name == 'posix' and sys.platform != 'darwin':
         # Linux, Unix, AIX, etc.
         # use ~/.config if empty OR not set
         xdg = env.get("XDG_CONFIG_HOME", None) or os.path.join(get_home_dir(), '.config')
         if xdg and _writable_dir(xdg):
             return py3compat.cast_unicode(xdg, fs_encoding)
 
     return None
 
 
 def get_xdg_cache_dir():
     """Return the XDG_CACHE_HOME, if it is defined and exists, else None.
 
     This is only for non-OS X posix (Linux,Unix,etc.) systems.
     """
 
     env = os.environ
 
     if os.name == 'posix' and sys.platform != 'darwin':
         # Linux, Unix, AIX, etc.
         # use ~/.cache if empty OR not set
         xdg = env.get("XDG_CACHE_HOME", None) or os.path.join(get_home_dir(), '.cache')
         if xdg and _writable_dir(xdg):
             return py3compat.cast_unicode(xdg, fs_encoding)
 
     return None
 
 
 def get_ipython_dir():
     """Get the IPython directory for this platform and user.
 
     This uses the logic in `get_home_dir` to find the home directory
     and then adds .ipython to the end of the path.
     """
 
     env = os.environ
     pjoin = os.path.join
 
 
     ipdir_def = '.ipython'
 
     home_dir = get_home_dir()
     xdg_dir = get_xdg_dir()
     
     # import pdb; pdb.set_trace()  # dbg
     if 'IPYTHON_DIR' in env:
         warnings.warn('The environment variable IPYTHON_DIR is deprecated. '
                       'Please use IPYTHONDIR instead.')
     ipdir = env.get('IPYTHONDIR', env.get('IPYTHON_DIR', None))
     if ipdir is None:
         # not set explicitly, use ~/.ipython
         ipdir = pjoin(home_dir, ipdir_def)
         if xdg_dir:
             # Several IPython versions (up to 1.x) defaulted to .config/ipython
             # on Linux. We have decided to go back to using .ipython everywhere
             xdg_ipdir = pjoin(xdg_dir, 'ipython')
 
             if _writable_dir(xdg_ipdir):
                 cu = compress_user
                 if os.path.exists(ipdir):
                     warnings.warn(('Ignoring {0} in favour of {1}. Remove {0} '
                     'to get rid of this message').format(cu(xdg_ipdir), cu(ipdir)))
                 else:
                     warnings.warn('Moving {0} to {1}'.format(cu(xdg_ipdir), cu(ipdir)))
                     os.rename(xdg_ipdir, ipdir)
 
     ipdir = os.path.normpath(os.path.expanduser(ipdir))
 
     if os.path.exists(ipdir) and not _writable_dir(ipdir):
         # ipdir exists, but is not writable
         warnings.warn("IPython dir '%s' is not a writable location,"
                         " using a temp directory."%ipdir)
         ipdir = tempfile.mkdtemp()
     elif not os.path.exists(ipdir):
         parent = os.path.dirname(ipdir)
         if not _writable_dir(parent):
             # ipdir does not exist and parent isn't writable
             warnings.warn("IPython parent '%s' is not a writable location,"
                         " using a temp directory."%parent)
             ipdir = tempfile.mkdtemp()
 
     return py3compat.cast_unicode(ipdir, fs_encoding)
 
 
 def get_ipython_cache_dir():
     """Get the cache directory it is created if it does not exist."""
     xdgdir = get_xdg_cache_dir()
     if xdgdir is None:
         return get_ipython_dir()
     ipdir = os.path.join(xdgdir, "ipython")
     if not os.path.exists(ipdir) and _writable_dir(xdgdir):
-        os.makedirs(ipdir)
+        ensure_dir_exists(ipdir)
     elif not _writable_dir(xdgdir):
         return get_ipython_dir()
 
     return py3compat.cast_unicode(ipdir, fs_encoding)
 
 
 def get_ipython_package_dir():
     """Get the base directory where IPython itself is installed."""
     ipdir = os.path.dirname(IPython.__file__)
     return py3compat.cast_unicode(ipdir, fs_encoding)
 
 
 def get_ipython_module_path(module_str):
     """Find the path to an IPython module in this version of IPython.
 
     This will always find the version of the module that is in this importable
     IPython package. This will always return the path to the ``.py``
     version of the module.
     """
     if module_str == 'IPython':
         return os.path.join(get_ipython_package_dir(), '__init__.py')
     mod = import_item(module_str)
     the_path = mod.__file__.replace('.pyc', '.py')
     the_path = the_path.replace('.pyo', '.py')
     return py3compat.cast_unicode(the_path, fs_encoding)
 
 def locate_profile(profile='default'):
     """Find the path to the folder associated with a given profile.
     
     I.e. find $IPYTHONDIR/profile_whatever.
     """
     from IPython.core.profiledir import ProfileDir, ProfileDirError
     try:
         pd = ProfileDir.find_profile_dir_by_name(get_ipython_dir(), profile)
     except ProfileDirError:
         # IOError makes more sense when people are expecting a path
         raise IOError("Couldn't find profile %r" % profile)
     return pd.location
 
 def expand_path(s):
     """Expand $VARS and ~names in a string, like a shell
 
     :Examples:
 
        In [2]: os.environ['FOO']='test'
 
        In [3]: expand_path('variable FOO is $FOO')
        Out[3]: 'variable FOO is test'
     """
     # This is a pretty subtle hack. When expand user is given a UNC path
     # on Windows (\\server\share$\%username%), os.path.expandvars, removes
     # the $ to get (\\server\share\%username%). I think it considered $
     # alone an empty var. But, we need the $ to remains there (it indicates
     # a hidden share).
     if os.name=='nt':
         s = s.replace('$\\', 'IPYTHON_TEMP')
     s = os.path.expandvars(os.path.expanduser(s))
     if os.name=='nt':
         s = s.replace('IPYTHON_TEMP', '$\\')
     return s
 
 
 def unescape_glob(string):
     """Unescape glob pattern in `string`."""
     def unescape(s):
         for pattern in '*[]!?':
             s = s.replace(r'\{0}'.format(pattern), pattern)
         return s
     return '\\'.join(map(unescape, string.split('\\\\')))
 
 
 def shellglob(args):
     """
     Do glob expansion for each element in `args` and return a flattened list.
 
     Unmatched glob pattern will remain as-is in the returned list.
 
     """
     expanded = []
     # Do not unescape backslash in Windows as it is interpreted as
     # path separator:
     unescape = unescape_glob if sys.platform != 'win32' else lambda x: x
     for a in args:
         expanded.extend(glob.glob(a) or [unescape(a)])
     return expanded
 
 
 def target_outdated(target,deps):
     """Determine whether a target is out of date.
 
     target_outdated(target,deps) -> 1/0
 
     deps: list of filenames which MUST exist.
     target: single filename which may or may not exist.
 
     If target doesn't exist or is older than any file listed in deps, return
     true, otherwise return false.
     """
     try:
         target_time = os.path.getmtime(target)
     except os.error:
         return 1
     for dep in deps:
         dep_time = os.path.getmtime(dep)
         if dep_time > target_time:
             #print "For target",target,"Dep failed:",dep # dbg
             #print "times (dep,tar):",dep_time,target_time # dbg
             return 1
     return 0
 
 
 def target_update(target,deps,cmd):
     """Update a target with a given command given a list of dependencies.
 
     target_update(target,deps,cmd) -> runs cmd if target is outdated.
 
     This is just a wrapper around target_outdated() which calls the given
     command if target is outdated."""
 
     if target_outdated(target,deps):
         system(cmd)
 
 def filehash(path):
     """Make an MD5 hash of a file, ignoring any differences in line
     ending characters."""
     with open(path, "rU") as f:
         return md5(py3compat.str_to_bytes(f.read())).hexdigest()
 
 # If the config is unmodified from the default, we'll just delete it.
 # These are consistent for 0.10.x, thankfully. We're not going to worry about
 # older versions.
 old_config_md5 = {'ipy_user_conf.py': 'fc108bedff4b9a00f91fa0a5999140d3',
                   'ipythonrc': '12a68954f3403eea2eec09dc8fe5a9b5'}
 
 def check_for_old_config(ipython_dir=None):
     """Check for old config files, and present a warning if they exist.
 
     A link to the docs of the new config is included in the message.
 
     This should mitigate confusion with the transition to the new
     config system in 0.11.
     """
     if ipython_dir is None:
         ipython_dir = get_ipython_dir()
 
     old_configs = ['ipy_user_conf.py', 'ipythonrc', 'ipython_config.py']
     warned = False
     for cfg in old_configs:
         f = os.path.join(ipython_dir, cfg)
         if os.path.exists(f):
             if filehash(f) == old_config_md5.get(cfg, ''):
                 os.unlink(f)
             else:
                 warnings.warn("Found old IPython config file %r (modified by user)"%f)
                 warned = True
 
     if warned:
         warnings.warn("""
   The IPython configuration system has changed as of 0.11, and these files will
   be ignored. See http://ipython.github.com/ipython-doc/dev/config for details
   of the new config system.
   To start configuring IPython, do `ipython profile create`, and edit
   `ipython_config.py` in <ipython_dir>/profile_default.
   If you need to leave the old config files in place for an older version of
   IPython and want to suppress this warning message, set
   `c.InteractiveShellApp.ignore_old_config=True` in the new config.""")
 
 def get_security_file(filename, profile='default'):
     """Return the absolute path of a security file given by filename and profile
     
     This allows users and developers to find security files without
     knowledge of the IPython directory structure. The search path
     will be ['.', profile.security_dir]
     
     Parameters
     ----------
     
     filename : str
         The file to be found. If it is passed as an absolute path, it will
         simply be returned.
     profile : str [default: 'default']
         The name of the profile to search.  Leaving this unspecified
         The file to be found. If it is passed as an absolute path, fname will
         simply be returned.
     
     Returns
     -------
     Raises :exc:`IOError` if file not found or returns absolute path to file.
     """
     # import here, because profiledir also imports from utils.path
     from IPython.core.profiledir import ProfileDir
     try:
         pd = ProfileDir.find_profile_dir_by_name(get_ipython_dir(), profile)
     except Exception:
         # will raise ProfileDirError if no such profile
         raise IOError("Profile %r not found")
     return filefind(filename, ['.', pd.security_dir])
 
 
 ENOLINK = 1998
 
 def link(src, dst):
     """Hard links ``src`` to ``dst``, returning 0 or errno.
 
     Note that the special errno ``ENOLINK`` will be returned if ``os.link`` isn't
     supported by the operating system.
     """
 
     if not hasattr(os, "link"):
         return ENOLINK
     link_errno = 0
     try:
         os.link(src, dst)
     except OSError as e:
         link_errno = e.errno
     return link_errno
 
 
 def link_or_copy(src, dst):
     """Attempts to hardlink ``src`` to ``dst``, copying if the link fails.
 
     Attempts to maintain the semantics of ``shutil.copy``.
 
     Because ``os.link`` does not overwrite files, a unique temporary file
     will be used if the target already exists, then that file will be moved
     into place.
     """
 
     if os.path.isdir(dst):
         dst = os.path.join(dst, os.path.basename(src))
 
     link_errno = link(src, dst)
     if link_errno == errno.EEXIST:
         new_dst = dst + "-temp-%04X" %(random.randint(1, 16**4), )
         try:
             link_or_copy(src, new_dst)
         except:
             try:
                 os.remove(new_dst)
             except OSError:
                 pass
             raise
         os.rename(new_dst, dst)
     elif link_errno != 0:
         # Either link isn't supported, or the filesystem doesn't support
         # linking, or 'src' and 'dst' are on different filesystems.
         shutil.copy(src, dst)
+
+def ensure_dir_exists(path, mode=0o777):
+    """ensure that a directory exists
+    
+    If it doesn't exist, try to create it and protect against a race condition
+    if another process is doing the same.
+    """
+    if not os.path.exists(path):
+        try:
+            os.makedirs(path, mode=mode)
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+    
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