Merge pull request #10136 from srinivasreddy/dead_people

remove python2 code

IPython/core/interactiveshell.py

@@ -1,3220 +1,3212 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.
 #-----------------------------------------------------------------------------
 
 
 import __future__
 import abc
 import ast
 import atexit
 import functools
 import os
 import re
 import runpy
 import sys
 import tempfile
 import traceback
 import types
 import subprocess
 import warnings
 from io import open as io_open
 
 from pickleshare import PickleShareDB
 
 from traitlets.config.configurable import SingletonConfigurable
 from IPython.core import 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 Alias, AliasManager
 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.debugger import Pdb
 from IPython.core.display_trap import DisplayTrap
 from IPython.core.displayhook import DisplayHook
 from IPython.core.displaypub import DisplayPublisher
 from IPython.core.error import InputRejected, UsageError
 from IPython.core.extensions import ExtensionManager
 from IPython.core.formatters import DisplayFormatter
 from IPython.core.history import HistoryManager
 from IPython.core.inputsplitter import 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.usage import default_banner
 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.paths import get_ipython_dir
 from IPython.utils.path import get_home_dir, get_py_filename, ensure_dir_exists
 from IPython.utils.process import system, getoutput
 from IPython.utils.py3compat import builtin_mod
 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.tempdir import TemporaryDirectory
 from traitlets import (
     Integer, Bool, CaselessStrEnum, Enum, List, Dict, Unicode, Instance, Type,
     observe, default,
 )
 from warnings import warn
 from logging import error
 import IPython.core.hooks
 
 # NoOpContext is deprecated, but ipykernel imports it from here.
 # See https://github.com/ipython/ipykernel/issues/157
 from IPython.utils.contexts import NoOpContext
 
 try:
     import docrepr.sphinxify as sphx
 
     def sphinxify(doc):
         with TemporaryDirectory() as dirname:
             return {
                 'text/html': sphx.sphinxify(doc, dirname),
                 'text/plain': doc
             }
 except ImportError:
     sphinxify = None
 
 
 class ProvisionalWarning(DeprecationWarning):
     """
     Warning class for unstable features
     """
     pass
 
 #-----------------------------------------------------------------------------
 # 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
 
 
 class SpaceInInput(Exception): pass
 
 
 def get_default_colors():
     "DEPRECATED"
     warn('get_default_color is Deprecated, and is `Neutral` on all platforms.',
             DeprecationWarning, stacklevel=2)
     return 'Neutral'
 
 
 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)
 
 
 @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
 
 
 class ExecutionResult(object):
     """The result of a call to :meth:`InteractiveShell.run_cell`
 
     Stores information about what took place.
     """
     execution_count = None
     error_before_exec = None
     error_in_exec = None
     result = None
 
     @property
     def success(self):
         return (self.error_before_exec is None) and (self.error_in_exec is None)
 
     def raise_error(self):
         """Reraises error if `success` is `False`, otherwise does nothing"""
         if self.error_before_exec is not None:
             raise self.error_before_exec
         if self.error_in_exec is not None:
             raise self.error_in_exec
 
     def __repr__(self):
         name = self.__class__.__qualname__
         return '<%s object at %x, execution_count=%s error_before_exec=%s error_in_exec=%s result=%s>' %\
                 (name, id(self), self.execution_count, self.error_before_exec, self.error_in_exec, repr(self.result))
 
 
 class InteractiveShell(SingletonConfigurable):
     """An enhanced, interactive shell for Python."""
 
     _instance = None
     
     ast_transformers = List([], help=
         """
         A list of ast.NodeTransformer subclass instances, which will be applied
         to user input before code is run.
         """
     ).tag(config=True)
 
     autocall = Enum((0,1,2), default_value=0, 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).
         """
     ).tag(config=True)
     # TODO: remove all autoindent logic and put into frontends.
     # We can't do this yet because even runlines uses the autoindent.
     autoindent = Bool(True, help=
         """
         Autoindent IPython code entered interactively.
         """
     ).tag(config=True)
 
     automagic = Bool(True, help=
         """
         Enable magic commands to be called without the leading %.
         """
     ).tag(config=True)
     
     banner1 = Unicode(default_banner,
         help="""The part of the banner to be printed before the profile"""
     ).tag(config=True)
     banner2 = Unicode('',
         help="""The part of the banner to be printed after the profile"""
     ).tag(config=True)
 
     cache_size = Integer(1000, 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
         """
     ).tag(config=True)
     color_info = Bool(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.
         """
     ).tag(config=True)
     colors = CaselessStrEnum(('Neutral', 'NoColor','LightBG','Linux'),
                              default_value='Neutral',
         help="Set the color scheme (NoColor, Neutral, Linux, or LightBG)."
     ).tag(config=True)
     debug = Bool(False).tag(config=True)
     disable_failing_post_execute = Bool(False,
         help="Don't call post-execute functions that have failed in the past."
     ).tag(config=True)
     display_formatter = Instance(DisplayFormatter, allow_none=True)
     displayhook_class = Type(DisplayHook)
     display_pub_class = Type(DisplayPublisher)
     
     sphinxify_docstring = Bool(False, help=
         """
         Enables rich html representation of docstrings. (This requires the
         docrepr module).
         """).tag(config=True)
 
     @observe("sphinxify_docstring")
     def _sphinxify_docstring_changed(self, change):
         if change['new']:
             warn("`sphinxify_docstring` is provisional since IPython 5.0 and might change in future versions." , ProvisionalWarning)
 
     enable_html_pager = Bool(False, help=
         """
         (Provisional API) enables html representation in mime bundles sent
         to pagers.
         """).tag(config=True)
 
     @observe("enable_html_pager")
     def _enable_html_pager_changed(self, change):
         if change['new']:
             warn("`enable_html_pager` is provisional since IPython 5.0 and might change in future versions.", ProvisionalWarning)
 
     data_pub_class = None
 
     exit_now = Bool(False)
     exiter = Instance(ExitAutocall)
     @default('exiter')
     def _exiter_default(self):
         return ExitAutocall(self)
     # Monotonically increasing execution counter
     execution_count = Integer(1)
     filename = Unicode("<ipython console>")
     ipython_dir= Unicode('').tag(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 = Bool(False, help=
         """
         Start logging to the default log file in overwrite mode.
         Use `logappend` to specify a log file to **append** logs to.
         """
     ).tag(config=True)
     logfile = Unicode('', help=
         """
         The name of the logfile to use.
         """
     ).tag(config=True)
     logappend = Unicode('', help=
         """
         Start logging to the given file in append mode.
         Use `logfile` to specify a log file to **overwrite** logs to.
         """
     ).tag(config=True)
     object_info_string_level = Enum((0,1,2), default_value=0,
     ).tag(config=True)
     pdb = Bool(False, help=
         """
         Automatically call the pdb debugger after every exception.
         """
     ).tag(config=True)
     display_page = Bool(False,
         help="""If True, anything that would be passed to the pager
         will be displayed as regular output instead."""
     ).tag(config=True)
 
     # deprecated prompt traits:
     
     prompt_in1 = Unicode('In [\\#]: ',
         help="Deprecated since IPython 4.0 and ignored since 5.0, set TerminalInteractiveShell.prompts object directly."
     ).tag(config=True)
     prompt_in2 = Unicode('   .\\D.: ',
         help="Deprecated since IPython 4.0 and ignored since 5.0, set TerminalInteractiveShell.prompts object directly."
     ).tag(config=True)
     prompt_out = Unicode('Out[\\#]: ',
         help="Deprecated since IPython 4.0 and ignored since 5.0, set TerminalInteractiveShell.prompts object directly."
     ).tag(config=True)
     prompts_pad_left = Bool(True,
         help="Deprecated since IPython 4.0 and ignored since 5.0, set TerminalInteractiveShell.prompts object directly."
     ).tag(config=True)
     
     @observe('prompt_in1', 'prompt_in2', 'prompt_out', 'prompt_pad_left')
     def _prompt_trait_changed(self, change):
         name = change['name']
         warn("InteractiveShell.{name} is deprecated since IPython 4.0"
              " and ignored since 5.0, set TerminalInteractiveShell.prompts"
              " object directly.".format(name=name))
         
         # protect against weird cases where self.config may not exist:
 
     show_rewritten_input = Bool(True,
         help="Show rewritten input, e.g. for autocall."
     ).tag(config=True)
 
     quiet = Bool(False).tag(config=True)
 
     history_length = Integer(10000,
         help='Total length of command history'
     ).tag(config=True)
 
     history_load_length = Integer(1000, help=
         """
         The number of saved history entries to be loaded
         into the history buffer at startup.
         """
     ).tag(config=True)
 
     ast_node_interactivity = Enum(['all', 'last', 'last_expr', 'none'],
                                   default_value='last_expr',
                                   help="""
         'all', 'last', 'last_expr' or 'none', specifying which nodes should be
         run interactively (displaying output from expressions)."""
     ).tag(config=True)
 
     # 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').tag(config=True)
     separate_out = SeparateUnicode('').tag(config=True)
     separate_out2 = SeparateUnicode('').tag(config=True)
     wildcards_case_sensitive = Bool(True).tag(config=True)
     xmode = CaselessStrEnum(('Context','Plain', 'Verbose'),
                             default_value='Context').tag(config=True)
 
     # Subcomponents of InteractiveShell
     alias_manager = Instance('IPython.core.alias.AliasManager', allow_none=True)
     prefilter_manager = Instance('IPython.core.prefilter.PrefilterManager', allow_none=True)
     builtin_trap = Instance('IPython.core.builtin_trap.BuiltinTrap', allow_none=True)
     display_trap = Instance('IPython.core.display_trap.DisplayTrap', allow_none=True)
     extension_manager = Instance('IPython.core.extensions.ExtensionManager', allow_none=True)
     payload_manager = Instance('IPython.core.payload.PayloadManager', allow_none=True)
     history_manager = Instance('IPython.core.history.HistoryAccessorBase', allow_none=True)
     magics_manager = Instance('IPython.core.magic.MagicsManager', allow_none=True)
 
     profile_dir = Instance('IPython.core.application.ProfileDir', allow_none=True)
     @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 = Dict()
 
     # Tracks any GUI loop loaded for pylab
     pylab_gui_select = None
 
     last_execution_succeeded = Bool(True, help='Did last executed command succeeded')
 
     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)
         if 'PromptManager' in self.config:
             warn('As of IPython 5.0 `PromptManager` config will have no effect'
                  ' and has been replaced by TerminalInteractiveShell.prompts_class')
         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_user_ns()
         self.init_logger()
         self.init_builtins()
 
         # The following was in post_config_initialization
         self.init_inspector()
         self.raw_input_original = input
         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_magics()
         self.init_alias()
         self.init_logstart()
         self.init_pdb()
         self.init_extension_manager()
         self.init_payload()
         self.init_deprecation_warnings()
         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
     #-------------------------------------------------------------------------
     @observe('ipython_dir')
     def _ipython_dir_changed(self, change):
         ensure_dir_exists(change['new'])
 
     def set_autoindent(self,value=None):
         """Set the autoindent flag.
 
         If called with no arguments, it acts as a toggle."""
         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 where we started running (mainly for crash post-mortem)
         # This is not being used anywhere currently.
         self.starting_dir = os.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'
 
 
     @observe('colors')
     def init_syntax_highlighting(self, changes=None):
         # Python source parser/formatter for syntax highlighting
         pyformat = PyColorize.Parser(style=self.colors, parent=self).format
         self.pycolorize = lambda src: pyformat(src,'str')
 
     def refresh_style(self):
         # No-op here, used in subclass
         pass
 
     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_deprecation_warnings(self):
         """
         register default filter for deprecation warning.
 
         This will allow deprecation warning of function used interactively to show
         warning to users, and still hide deprecation warning from libraries import.
         """
         warnings.filterwarnings("default", category=DeprecationWarning, module=self.user_ns.get("__name__"))
 
     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
 
         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.
         # io.std* are deprecated, but don't show our own deprecation warnings
         # during initialization of the deprecated API.
         with warnings.catch_warnings():
             warnings.simplefilter('ignore', DeprecationWarning)
             io.stdout = io.IOStream(sys.stdout)
             io.stderr = io.IOStream(sys.stderr)
 
     def init_prompts(self):
         # 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_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 = os.path.normcase(sys.executable)
         paths = [p]
         while os.path.islink(p):
             p = os.path.normcase(os.path.join(os.path.dirname(p), os.readlink(p)))
             paths.append(p)
         p_venv = os.path.normcase(os.environ['VIRTUAL_ENV'])
         if any(p.startswith(p_venv) 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 = {'stdin': sys.stdin,
                                        'stdout': sys.stdout,
                                        'stderr': sys.stderr,
                                        '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 self._orig_sys_module_state.items():
                 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 the banner
     #-------------------------------------------------------------------------
     
     @property
     def banner(self):
         banner = self.banner1
         if self.profile and self.profile != 'default':
             banner += '\nIPython profile: %s\n' % self.profile
         if self.banner2:
             banner += '\n' + self.banner2
         return banner
 
     def show_banner(self, banner=None):
         if banner is None:
             banner = self.banner
         sys.stdout.write(banner)
     
     #-------------------------------------------------------------------------
     # 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)
         
         if self.display_page:
             self.set_hook('show_in_pager', page.as_hook(page.display_page), 90)
     
     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), stacklevel=2)
 
         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)
 
         self.events.register("pre_execute", self._clear_warning_registry)
 
     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.", stacklevel=2)
         self.events.register('post_run_cell', func)
     
     def _clear_warning_registry(self):
         # clear the warning registry, so that different code blocks with
         # overlapping line number ranges don't cause spurious suppression of
         # warnings (see gh-6611 for details)
         if "__warningregistry__" in self.user_global_ns:
             del self.user_global_ns["__warningregistry__"]
 
     #-------------------------------------------------------------------------
     # 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(
                         py3compat.cast_bytes_py2(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 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
 
         self.InteractiveTB.debugger(force=True)
 
     #-------------------------------------------------------------------------
     # 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 doctest 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 they 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 ns.items() 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, (str, list, tuple)):
             if isinstance(variables, str):
                 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 variables.items():
             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)
 
         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;
         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 idx, part in enumerate(oname_rest):
                     try:
                         parent = obj
                         # The last part is looked up in a special way to avoid
                         # descriptor invocation as it may raise or have side
                         # effects.
                         if idx == len(oname_rest) - 1:
                             obj = self._getattr_property(obj, part)
                         else:
                             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
                 isalias = isinstance(obj, Alias)
 
         # 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}
 
     @staticmethod
     def _getattr_property(obj, attrname):
         """Property-aware getattr to use in object finding.
 
         If attrname represents a property, return it unevaluated (in case it has
         side effects or raises an error.
 
         """
         if not isinstance(obj, type):
             try:
                 # `getattr(type(obj), attrname)` is not guaranteed to return
                 # `obj`, but does so for property:
                 #
                 # property.__get__(self, None, cls) -> self
                 #
                 # The universal alternative is to traverse the mro manually
                 # searching for attrname in class dicts.
                 attr = getattr(type(obj), attrname)
             except AttributeError:
                 pass
             else:
                 # This relies on the fact that data descriptors (with both
                 # __get__ & __set__ magic methods) take precedence over
                 # instance-level attributes:
                 #
                 #    class A(object):
                 #        @property
                 #        def foobar(self): return 123
                 #    a = A()
                 #    a.__dict__['foobar'] = 345
                 #    a.foobar  # == 123
                 #
                 # So, a property may be returned right away.
                 if isinstance(attr, property):
                     return attr
 
         # Nothing helped, fall back.
         return getattr(obj, attrname)
 
     def _object_find(self, oname, namespaces=None):
         """Find an object and return a struct with info about it."""
         return Struct(self._ofind(oname, namespaces))
 
     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)
         docformat = sphinxify if self.sphinxify_docstring else None
         if info.found:
             pmethod = getattr(self.inspector, meth)
             # TODO: only apply format_screen to the plain/text repr of the mime
             # bundle.
             formatter = format_screen if info.ismagic else docformat
             if meth == 'pdoc':
                 pmethod(info.obj, oname, formatter)
             elif meth == 'pinfo':
                 pmethod(info.obj, oname, formatter, info, 
                         enable_html_pager=self.enable_html_pager, **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):
         """Get object info about oname"""
         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)
 
     def object_inspect_text(self, oname, detail_level=0):
         """Get object info as formatted text"""
         return self.object_inspect_mime(oname, detail_level)['text/plain']
 
     def object_inspect_mime(self, oname, detail_level=0):
         """Get object info as a mimebundle of formatted representations.
 
         A mimebundle is a dictionary, keyed by mime-type.
         It must always have the key `'text/plain'`.
         """
         with self.builtin_trap:
             info = self._object_find(oname)
             if info.found:
                 return self.inspector._get_info(info.obj, oname, info=info,
                             detail_level=detail_level
                 )
             else:
                 raise KeyError(oname)
 
     #-------------------------------------------------------------------------
     # 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)
     #-------------------------------------------------------------------------
 
     debugger_cls = Pdb
 
     def init_traceback_handlers(self, custom_exceptions):
         # Syntax error handler.
         self.SyntaxTB = ultratb.SyntaxTB(color_scheme='NoColor', parent=self)
 
         # 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,
                                    debugger_cls=self.debugger_cls, parent=self)
 
         # 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, str):
                 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, str):
                     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=sys.stderr)
                     # show the exception in handler first
                     stb = self.InteractiveTB.structured_traceback(*sys.exc_info())
                     print(self.InteractiveTB.stb2text(stb))
                     print("The original exception:")
                     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.
         """
         print("UsageError: %s" % exc, file=sys.stderr)
     
     def get_exception_only(self, exc_tuple=None):
         """
         Return as a string (ending with a newline) the exception that
         just occurred, without any traceback.
         """
         etype, value, tb = self._get_exc_info(exc_tuple)
         msg = traceback.format_exception_only(etype, value)
         return ''.join(msg)
 
     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:
                 print('No traceback available to show.', file=sys.stderr)
                 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:
             print('\n' + self.get_exception_only(), file=sys.stderr)
 
     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))
 
     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):
         """DEPRECATED
         
         Moved to terminal subclass, here only to simplify the init logic."""
         # Set a number of methods that depend on readline to be no-op
         warnings.warn('`init_readline` is no-op since IPython 5.0 and is Deprecated',
                 DeprecationWarning, stacklevel=2)
         self.set_custom_completer = no_op
 
     @skip_doctest
     def set_next_input(self, s, replace=False):
         """ Sets the 'default' input string for the next command line.
 
         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)
 
     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), programmatically (such as in test suites) or out-of-process
         (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,
                                      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', module_completer, str_key = '%aimport')
         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')
 
 
     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_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.register_magics(m.AutoMagics, m.BasicMagics, m.CodeMagics,
             m.ConfigMagics, 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, str):
             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)
                 try:
                     ec = os.system(cmd)
                 except KeyboardInterrupt:
                     print('\n' + self.get_exception_only(), file=sys.stderr)
                     ec = -2
         else:
             # For posix the result of the subprocess.call() below is an exit
             # code, which by convention is zero for success, positive for
             # program failure.  Exit codes above 128 are reserved for signals,
             # and the formula for converting a signal to an exit code is usually
             # signal_number+128.  To more easily differentiate between exit
             # codes and signals, ipython uses negative numbers.  For instance
             # since control-c is signal 2 but exit code 130, ipython's
             # _exit_code variable will read -2.  Note that some shells like
             # csh and fish don't follow sh/bash conventions for exit codes.
             executable = os.environ.get('SHELL', None)
             try:
                 # Use env shell instead of default /bin/sh
                 ec = subprocess.call(cmd, shell=True, executable=executable)
             except KeyboardInterrupt:
                 # intercept control-C; a long traceback is not useful here
                 print('\n' + self.get_exception_only(), file=sys.stderr)
                 ec = 130
             if ec > 128:
                 ec = -(ec - 128)
         
         # 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.  Note the semantics
         # of _exit_code: for control-c, _exit_code == -signal.SIGNIT,
         # but raising SystemExit(_exit_code) will give status 254!
         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 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
 
         # This is overridden in TerminalInteractiveShell to use fancy prompts
         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_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' : 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
         """
         
         data, md = self.display_formatter.format(obj)
         value = {
             'status' : 'ok',
             'data' : data,
             'metadata' : md,
         }
         return value
     
     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 expressions.items():
             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.
         shell_futures : bool (False)
             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.
 
         """
         kw.setdefault('exit_ignore', False)
         kw.setdefault('raise_exceptions', False)
         kw.setdefault('shell_futures', False)
 
         fname = os.path.abspath(os.path.expanduser(fname))
 
         # Make sure we can open the file
         try:
             with open(fname):
                 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), self.builtin_trap:
             try:
                 glob, loc = (where + (None, ))[:2]
                 py3compat.execfile(
                     fname, glob, loc,
                     self.compile if kw['shell_futures'] else None)
             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 status.code:
                     if kw['raise_exceptions']:
                         raise
                     if 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, shell_futures=False, raise_exceptions=False):
         """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.
         shell_futures : bool (False)
             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.
         raise_exceptions : bool (False)
             If True raise exceptions everywhere.  Meant for testing.
         """
         fname = os.path.abspath(os.path.expanduser(fname))
 
         # Make sure we can open the file
         try:
             with open(fname):
                 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 nbformat import read
                 with io_open(fname) as f:
                     nb = read(f, as_version=4)
                     if not nb.cells:
                         return
                     for cell in nb.cells:
                         if cell.cell_type == 'code':
                             yield cell.source
             else:
                 with open(fname) as f:
                     yield f.read()
 
         with prepended_to_syspath(dname):
             try:
                 for cell in get_cells():
                     result = self.run_cell(cell, silent=True, shell_futures=shell_futures)
                     if raise_exceptions:
                         result.raise_error()
                     elif not result.success:
                         break
             except:
                 if raise_exceptions:
                     raise
                 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_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.
 
         Returns
         -------
         result : :class:`ExecutionResult`
         """
         result = ExecutionResult()
 
         if (not raw_cell) or raw_cell.isspace():
             self.last_execution_succeeded = True
             return result
         
         if silent:
             store_history = False
 
         if store_history:
             result.execution_count = self.execution_count
 
         def error_before_exec(value):
             result.error_before_exec = value
             self.last_execution_succeeded = False
             return result
 
         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 error_before_exec(preprocessing_exc_tuple[2])
 
         # 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 self.custom_exceptions as e:
                     etype, value, tb = sys.exc_info()
                     self.CustomTB(etype, value, tb)
                     return error_before_exec(e)
                 except IndentationError as e:
                     self.showindentationerror()
                     if store_history:
                         self.execution_count += 1
                     return error_before_exec(e)
                 except (OverflowError, SyntaxError, ValueError, TypeError,
                         MemoryError) as e:
                     self.showsyntaxerror()
                     if store_history:
                         self.execution_count += 1
                     return error_before_exec(e)
 
                 # Apply AST transformations
                 try:
                     code_ast = self.transform_ast(code_ast)
                 except InputRejected as e:
                     self.showtraceback()
                     if store_history:
                         self.execution_count += 1
                     return error_before_exec(e)
 
                 # Give the displayhook a reference to our ExecutionResult so it
                 # can fill in the output value.
                 self.displayhook.exec_result = result
 
                 # Execute the user code
                 interactivity = "none" if silent else self.ast_node_interactivity
                 has_raised = self.run_ast_nodes(code_ast.body, cell_name,
                    interactivity=interactivity, compiler=compiler, result=result)
                 
                 self.last_execution_succeeded = not has_raised
 
                 # Reset this so later displayed values do not modify the
                 # ExecutionResult
                 self.displayhook.exec_result = None
 
                 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
 
         return result
     
     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 InputRejected:
                 # User-supplied AST transformers can reject an input by raising
                 # an InputRejected.  Short-circuit in this case so that we
                 # don't unregister the transform.
                 raise
             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, result=None):
         """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().
         result : ExecutionResult, optional
           An object to store exceptions that occur during execution.
 
         Returns
         -------
         True if an exception occurred while running code, False if it finished
         running.
         """
         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)
 
         try:
             for i, node in enumerate(to_run_exec):
                 mod = ast.Module([node])
                 code = compiler(mod, cell_name, "exec")
                 if self.run_code(code, result):
                     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, result):
                     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.
             if result:
                 result.error_before_exec = sys.exc_info()[1]
             self.showtraceback()
             return True
 
         return False
 
     def run_code(self, code_obj, result=None):
         """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
         result : ExecutionResult, optional
           An object to store exceptions that occur during execution.
 
         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 as e:
             if result is not None:
                 result.error_in_exec = e
             self.showtraceback(exception_only=True)
             warn("To exit: use 'exit', 'quit', or Ctrl-D.", stacklevel=1)
         except self.custom_exceptions:
             etype, value, tb = sys.exc_info()
             if result is not None:
                 result.error_in_exec = value
             self.CustomTB(etype, value, tb)
         except:
             if result is not None:
                 result.error_in_exec = sys.exc_info()[1]
             self.showtraceback()
         else:
             outflag = 0
         return outflag
 
     # For backwards compatibility
     runcode = run_code
 
     #-------------------------------------------------------------------------
     # Things related to GUI support and pylab
     #-------------------------------------------------------------------------
 
     active_eventloop = None
 
     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 = {"__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()
         try:
             frame = sys._getframe(depth+1)
         except ValueError:
             # This is thrown if there aren't that many frames on the stack,
             # e.g. if a script called run_line_magic() directly.
             pass
         else:
             ns.update(frame.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)
         os.close(handle)  # On Windows, there can only be one open handle on a file
         self.tempfiles.append(filename)
 
         if data:
             tmp_file = open(filename,'w')
             tmp_file.write(data)
             tmp_file.close()
         return filename
 
     @undoc
     def write(self,data):
         """DEPRECATED: Write a string to the default output"""
         warn('InteractiveShell.write() is deprecated, use sys.stdout instead',
              DeprecationWarning, stacklevel=2)
         sys.stdout.write(data)
 
     @undoc
     def write_err(self,data):
         """DEPRECATED: Write a string to the default error output"""
         warn('InteractiveShell.write_err() is deprecated, use sys.stderr instead',
              DeprecationWarning, stacklevel=2)
         sys.stderr.write(data)
 
     def ask_yes_no(self, prompt, default=None, interrupt=None):
         if self.quiet:
             return True
         return ask_yes_no(prompt,default,interrupt)
 
     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,
           corresponding .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
         try:
             if target.startswith(('http://', 'https://')):
                 return openpy.read_py_url(target, skip_encoding_cookie=skip_encoding_cookie)
         except UnicodeDecodeError:
             if not py_only :
                 # Deferred import
                 from urllib.request import urlopen
                 response = urlopen(target)
                 return response.read().decode('latin1')
             raise ValueError(("'%s' seem to be unreadable.") % target)
 
         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, str):
             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()
 
 
     # Overridden in terminal subclass to change prompts
     def switch_doctest_mode(self, mode):
         pass
 
 
 class InteractiveShellABC(metaclass=abc.ABCMeta):
     """An abstract base class for InteractiveShell."""
 
 InteractiveShellABC.register(InteractiveShell)

IPython/core/ultratb.py

@@ -1,1488 +1,1469 b''
 # -*- coding: utf-8 -*-
 """
 Verbose and colourful traceback formatting.
 
 **ColorTB**
 
 I've always found it a bit hard to visually parse tracebacks in Python.  The
 ColorTB class is a solution to that problem.  It colors the different parts of a
 traceback in a manner similar to what you would expect from a syntax-highlighting
 text editor.
 
 Installation instructions for ColorTB::
 
     import sys,ultratb
     sys.excepthook = ultratb.ColorTB()
 
 **VerboseTB**
 
 I've also included a port of Ka-Ping Yee's "cgitb.py" that produces all kinds
 of useful info when a traceback occurs.  Ping originally had it spit out HTML
 and intended it for CGI programmers, but why should they have all the fun?  I
 altered it to spit out colored text to the terminal.  It's a bit overwhelming,
 but kind of neat, and maybe useful for long-running programs that you believe
 are bug-free.  If a crash *does* occur in that type of program you want details.
 Give it a shot--you'll love it or you'll hate it.
 
 .. note::
 
   The Verbose mode prints the variables currently visible where the exception
   happened (shortening their strings if too long). This can potentially be
   very slow, if you happen to have a huge data structure whose string
   representation is complex to compute. Your computer may appear to freeze for
   a while with cpu usage at 100%. If this occurs, you can cancel the traceback
   with Ctrl-C (maybe hitting it more than once).
 
   If you encounter this kind of situation often, you may want to use the
   Verbose_novars mode instead of the regular Verbose, which avoids formatting
   variables (but otherwise includes the information and context given by
   Verbose).
 
 .. note::
 
   The verbose mode print all variables in the stack, which means it can
   potentially leak sensitive information like access keys, or unencryted
   password.
 
 Installation instructions for VerboseTB::
 
     import sys,ultratb
     sys.excepthook = ultratb.VerboseTB()
 
 Note:  Much of the code in this module was lifted verbatim from the standard
 library module 'traceback.py' and Ka-Ping Yee's 'cgitb.py'.
 
 Color schemes
 -------------
 
 The colors are defined in the class TBTools through the use of the
 ColorSchemeTable class. Currently the following exist:
 
   - NoColor: allows all of this module to be used in any terminal (the color
     escapes are just dummy blank strings).
 
   - Linux: is meant to look good in a terminal like the Linux console (black
     or very dark background).
 
   - LightBG: similar to Linux but swaps dark/light colors to be more readable
     in light background terminals.
 
   - Neutral: a neutral color scheme that should be readable on both light and
     dark background
 
 You can implement other color schemes easily, the syntax is fairly
 self-explanatory. Please send back new schemes you develop to the author for
 possible inclusion in future releases.
 
 Inheritance diagram:
 
 .. inheritance-diagram:: IPython.core.ultratb
    :parts: 3
 """
 
 #*****************************************************************************
 # Copyright (C) 2001 Nathaniel Gray <[e-mail]>
 # Copyright (C) 2001-2004 Fernando Perez <[e-mail]>
 #
 # Distributed under the terms of the BSD License.  The full license is in
 # the file COPYING, distributed as part of this software.
 #*****************************************************************************
 
 
 import dis
 import inspect
 import keyword
 import linecache
 import os
 import pydoc
 import re
 import sys
 import time
 import tokenize
 import traceback
 import types
 
 try:  # Python 2
     generate_tokens = tokenize.generate_tokens
 except AttributeError:  # Python 3
     generate_tokens = tokenize.tokenize
 
 # For purposes of monkeypatching inspect to fix a bug in it.
 from inspect import getsourcefile, getfile, getmodule, \
     ismodule, isclass, ismethod, isfunction, istraceback, isframe, iscode
 
 # IPython's own modules
 from IPython import get_ipython
 from IPython.core import debugger
 from IPython.core.display_trap import DisplayTrap
 from IPython.core.excolors import exception_colors
 from IPython.utils import PyColorize
 from IPython.utils import openpy
 from IPython.utils import path as util_path
 from IPython.utils import py3compat
 from IPython.utils import ulinecache
 from IPython.utils.data import uniq_stable
 from IPython.utils.terminal import get_terminal_size
 from logging import info, error
 
 import IPython.utils.colorable as colorable
 
 # Globals
 # amount of space to put line numbers before verbose tracebacks
 INDENT_SIZE = 8
 
 # Default color scheme.  This is used, for example, by the traceback
 # formatter.  When running in an actual IPython instance, the user's rc.colors
 # value is used, but having a module global makes this functionality available
 # to users of ultratb who are NOT running inside ipython.
 DEFAULT_SCHEME = 'NoColor'
 
 # ---------------------------------------------------------------------------
 # Code begins
 
 # Utility functions
 def inspect_error():
     """Print a message about internal inspect errors.
 
     These are unfortunately quite common."""
 
     error('Internal Python error in the inspect module.\n'
           'Below is the traceback from this internal error.\n')
 
 
 # This function is a monkeypatch we apply to the Python inspect module. We have
 # now found when it's needed (see discussion on issue gh-1456), and we have a
 # test case (IPython.core.tests.test_ultratb.ChangedPyFileTest) that fails if
 # the monkeypatch is not applied. TK, Aug 2012.
 def findsource(object):
     """Return the entire source file and starting line number for an object.
 
     The argument may be a module, class, method, function, traceback, frame,
     or code object.  The source code is returned as a list of all the lines
     in the file and the line number indexes a line in that list.  An IOError
     is raised if the source code cannot be retrieved.
 
     FIXED version with which we monkeypatch the stdlib to work around a bug."""
 
     file = getsourcefile(object) or getfile(object)
     # If the object is a frame, then trying to get the globals dict from its
     # module won't work. Instead, the frame object itself has the globals
     # dictionary.
     globals_dict = None
     if inspect.isframe(object):
         # XXX: can this ever be false?
         globals_dict = object.f_globals
     else:
         module = getmodule(object, file)
         if module:
             globals_dict = module.__dict__
     lines = linecache.getlines(file, globals_dict)
     if not lines:
         raise IOError('could not get source code')
 
     if ismodule(object):
         return lines, 0
 
     if isclass(object):
         name = object.__name__
         pat = re.compile(r'^(\s*)class\s*' + name + r'\b')
         # make some effort to find the best matching class definition:
         # use the one with the least indentation, which is the one
         # that's most probably not inside a function definition.
         candidates = []
         for i in range(len(lines)):
             match = pat.match(lines[i])
             if match:
                 # if it's at toplevel, it's already the best one
                 if lines[i][0] == 'c':
                     return lines, i
                 # else add whitespace to candidate list
                 candidates.append((match.group(1), i))
         if candidates:
             # this will sort by whitespace, and by line number,
             # less whitespace first
             candidates.sort()
             return lines, candidates[0][1]
         else:
             raise IOError('could not find class definition')
 
     if ismethod(object):
         object = object.__func__
     if isfunction(object):
         object = object.__code__
     if istraceback(object):
         object = object.tb_frame
     if isframe(object):
         object = object.f_code
     if iscode(object):
         if not hasattr(object, 'co_firstlineno'):
             raise IOError('could not find function definition')
         pat = re.compile(r'^(\s*def\s)|(.*(?<!\w)lambda(:|\s))|^(\s*@)')
         pmatch = pat.match
         # fperez - fix: sometimes, co_firstlineno can give a number larger than
         # the length of lines, which causes an error.  Safeguard against that.
         lnum = min(object.co_firstlineno, len(lines)) - 1
         while lnum > 0:
             if pmatch(lines[lnum]):
                 break
             lnum -= 1
 
         return lines, lnum
     raise IOError('could not find code object')
 
 
 # This is a patched version of inspect.getargs that applies the (unmerged)
 # patch for http://bugs.python.org/issue14611 by Stefano Taschini.  This fixes
 # https://github.com/ipython/ipython/issues/8205 and
 # https://github.com/ipython/ipython/issues/8293
 def getargs(co):
     """Get information about the arguments accepted by a code object.
 
     Three things are returned: (args, varargs, varkw), where 'args' is
     a list of argument names (possibly containing nested lists), and
     'varargs' and 'varkw' are the names of the * and ** arguments or None."""
     if not iscode(co):
         raise TypeError('{!r} is not a code object'.format(co))
 
     nargs = co.co_argcount
     names = co.co_varnames
     args = list(names[:nargs])
     step = 0
 
     # The following acrobatics are for anonymous (tuple) arguments.
     for i in range(nargs):
         if args[i][:1] in ('', '.'):
             stack, remain, count = [], [], []
             while step < len(co.co_code):
                 op = ord(co.co_code[step])
                 step = step + 1
                 if op >= dis.HAVE_ARGUMENT:
                     opname = dis.opname[op]
                     value = ord(co.co_code[step]) + ord(co.co_code[step+1])*256
                     step = step + 2
                     if opname in ('UNPACK_TUPLE', 'UNPACK_SEQUENCE'):
                         remain.append(value)
                         count.append(value)
                     elif opname in ('STORE_FAST', 'STORE_DEREF'):
                         if op in dis.haslocal:
                             stack.append(co.co_varnames[value])
                         elif op in dis.hasfree:
                             stack.append((co.co_cellvars + co.co_freevars)[value])
                         # Special case for sublists of length 1: def foo((bar))
                         # doesn't generate the UNPACK_TUPLE bytecode, so if
                         # `remain` is empty here, we have such a sublist.
                         if not remain:
                             stack[0] = [stack[0]]
                             break
                         else:
                             remain[-1] = remain[-1] - 1
                             while remain[-1] == 0:
                                 remain.pop()
                                 size = count.pop()
                                 stack[-size:] = [stack[-size:]]
                                 if not remain:
                                     break
                                 remain[-1] = remain[-1] - 1
                             if not remain:
                                 break
             args[i] = stack[0]
 
     varargs = None
     if co.co_flags & inspect.CO_VARARGS:
         varargs = co.co_varnames[nargs]
         nargs = nargs + 1
     varkw = None
     if co.co_flags & inspect.CO_VARKEYWORDS:
         varkw = co.co_varnames[nargs]
     return inspect.Arguments(args, varargs, varkw)
 
 
 # Monkeypatch inspect to apply our bugfix.
 def with_patch_inspect(f):
     """decorator for monkeypatching inspect.findsource"""
 
     def wrapped(*args, **kwargs):
         save_findsource = inspect.findsource
         save_getargs = inspect.getargs
         inspect.findsource = findsource
         inspect.getargs = getargs
         try:
             return f(*args, **kwargs)
         finally:
             inspect.findsource = save_findsource
             inspect.getargs = save_getargs
 
     return wrapped
 
 
 if py3compat.PY3:
     fixed_getargvalues = inspect.getargvalues
 else:
     # Fixes for https://github.com/ipython/ipython/issues/8293
     #       and https://github.com/ipython/ipython/issues/8205.
     # The relevant bug is caused by failure to correctly handle anonymous tuple
     # unpacking, which only exists in Python 2.
     fixed_getargvalues = with_patch_inspect(inspect.getargvalues)
 
 
 def fix_frame_records_filenames(records):
     """Try to fix the filenames in each record from inspect.getinnerframes().
 
     Particularly, modules loaded from within zip files have useless filenames
     attached to their code object, and inspect.getinnerframes() just uses it.
     """
     fixed_records = []
     for frame, filename, line_no, func_name, lines, index in records:
         # Look inside the frame's globals dictionary for __file__,
         # which should be better. However, keep Cython filenames since
         # we prefer the source filenames over the compiled .so file.
         filename = py3compat.cast_unicode_py2(filename, "utf-8")
         if not filename.endswith(('.pyx', '.pxd', '.pxi')):
             better_fn = frame.f_globals.get('__file__', None)
             if isinstance(better_fn, str):
                 # Check the type just in case someone did something weird with
                 # __file__. It might also be None if the error occurred during
                 # import.
                 filename = better_fn
         fixed_records.append((frame, filename, line_no, func_name, lines, index))
     return fixed_records
 
 
 @with_patch_inspect
 def _fixed_getinnerframes(etb, context=1, tb_offset=0):
     LNUM_POS, LINES_POS, INDEX_POS = 2, 4, 5
 
     records = fix_frame_records_filenames(inspect.getinnerframes(etb, context))
     # If the error is at the console, don't build any context, since it would
     # otherwise produce 5 blank lines printed out (there is no file at the
     # console)
     rec_check = records[tb_offset:]
     try:
         rname = rec_check[0][1]
         if rname == '<ipython console>' or rname.endswith('<string>'):
             return rec_check
     except IndexError:
         pass
 
     aux = traceback.extract_tb(etb)
     assert len(records) == len(aux)
     for i, (file, lnum, _, _) in zip(range(len(records)), aux):
         maybeStart = lnum - 1 - context // 2
         start = max(maybeStart, 0)
         end = start + context
         lines = ulinecache.getlines(file)[start:end]
         buf = list(records[i])
         buf[LNUM_POS] = lnum
         buf[INDEX_POS] = lnum - 1 - start
         buf[LINES_POS] = lines
         records[i] = tuple(buf)
     return records[tb_offset:]
 
 # Helper function -- largely belongs to VerboseTB, but we need the same
 # functionality to produce a pseudo verbose TB for SyntaxErrors, so that they
 # can be recognized properly by ipython.el's py-traceback-line-re
 # (SyntaxErrors have to be treated specially because they have no traceback)
 
 
 def _format_traceback_lines(lnum, index, lines, Colors, lvals=None,  _line_format=(lambda x,_:x,None)):
     numbers_width = INDENT_SIZE - 1
     res = []
     i = lnum - index
 
     for line in lines:
         line = py3compat.cast_unicode(line)
 
         new_line, err = _line_format(line, 'str')
         if not err: line = new_line
 
         if i == lnum:
             # This is the line with the error
             pad = numbers_width - len(str(i))
             num = '%s%s' % (debugger.make_arrow(pad), str(lnum))
             line = '%s%s%s %s%s' % (Colors.linenoEm, num,
                                     Colors.line, line, Colors.Normal)
         else:
             num = '%*s' % (numbers_width, i)
             line = '%s%s%s %s' % (Colors.lineno, num,
                                   Colors.Normal, line)
 
         res.append(line)
         if lvals and i == lnum:
             res.append(lvals + '\n')
         i = i + 1
     return res
 
 def is_recursion_error(etype, value, records):
     try:
         # RecursionError is new in Python 3.5
         recursion_error_type = RecursionError
     except NameError:
         recursion_error_type = RuntimeError
 
     # The default recursion limit is 1000, but some of that will be taken up
     # by stack frames in IPython itself. >500 frames probably indicates
     # a recursion error.
     return (etype is recursion_error_type) \
            and "recursion" in str(value).lower() \
            and len(records) > 500
 
 def find_recursion(etype, value, records):
     """Identify the repeating stack frames from a RecursionError traceback
 
     'records' is a list as returned by VerboseTB.get_records()
 
     Returns (last_unique, repeat_length)
     """
     # This involves a bit of guesswork - we want to show enough of the traceback
     # to indicate where the recursion is occurring. We guess that the innermost
     # quarter of the traceback (250 frames by default) is repeats, and find the
     # first frame (from in to out) that looks different.
     if not is_recursion_error(etype, value, records):
         return len(records), 0
 
     # Select filename, lineno, func_name to track frames with
     records = [r[1:4] for r in records]
     inner_frames = records[-(len(records)//4):]
     frames_repeated = set(inner_frames)
 
     last_seen_at = {}
     longest_repeat = 0
     i = len(records)
     for frame in reversed(records):
         i -= 1
         if frame not in frames_repeated:
             last_unique = i
             break
 
         if frame in last_seen_at:
             distance = last_seen_at[frame] - i
             longest_repeat = max(longest_repeat, distance)
 
         last_seen_at[frame] = i
     else:
         last_unique = 0 # The whole traceback was recursion
 
     return last_unique, longest_repeat
 
 #---------------------------------------------------------------------------
 # Module classes
 class TBTools(colorable.Colorable):
     """Basic tools used by all traceback printer classes."""
 
     # Number of frames to skip when reporting tracebacks
     tb_offset = 0
 
     def __init__(self, color_scheme='NoColor', call_pdb=False, ostream=None, parent=None, config=None):
         # Whether to call the interactive pdb debugger after printing
         # tracebacks or not
         super(TBTools, self).__init__(parent=parent, config=config)
         self.call_pdb = call_pdb
 
         # Output stream to write to.  Note that we store the original value in
         # a private attribute and then make the public ostream a property, so
         # that we can delay accessing sys.stdout until runtime.  The way
         # things are written now, the sys.stdout object is dynamically managed
         # so a reference to it should NEVER be stored statically.  This
         # property approach confines this detail to a single location, and all
         # subclasses can simply access self.ostream for writing.
         self._ostream = ostream
 
         # Create color table
         self.color_scheme_table = exception_colors()
 
         self.set_colors(color_scheme)
         self.old_scheme = color_scheme  # save initial value for toggles
 
         if call_pdb:
             self.pdb = debugger.Pdb()
         else:
             self.pdb = None
 
     def _get_ostream(self):
         """Output stream that exceptions are written to.
 
         Valid values are:
 
         - None: the default, which means that IPython will dynamically resolve
           to sys.stdout.  This ensures compatibility with most tools, including
           Windows (where plain stdout doesn't recognize ANSI escapes).
 
         - Any object with 'write' and 'flush' attributes.
         """
         return sys.stdout if self._ostream is None else self._ostream
 
     def _set_ostream(self, val):
         assert val is None or (hasattr(val, 'write') and hasattr(val, 'flush'))
         self._ostream = val
 
     ostream = property(_get_ostream, _set_ostream)
 
     def set_colors(self, *args, **kw):
         """Shorthand access to the color table scheme selector method."""
 
         # Set own color table
         self.color_scheme_table.set_active_scheme(*args, **kw)
         # for convenience, set Colors to the active scheme
         self.Colors = self.color_scheme_table.active_colors
         # Also set colors of debugger
         if hasattr(self, 'pdb') and self.pdb is not None:
             self.pdb.set_colors(*args, **kw)
 
     def color_toggle(self):
         """Toggle between the currently active color scheme and NoColor."""
 
         if self.color_scheme_table.active_scheme_name == 'NoColor':
             self.color_scheme_table.set_active_scheme(self.old_scheme)
             self.Colors = self.color_scheme_table.active_colors
         else:
             self.old_scheme = self.color_scheme_table.active_scheme_name
             self.color_scheme_table.set_active_scheme('NoColor')
             self.Colors = self.color_scheme_table.active_colors
 
     def stb2text(self, stb):
         """Convert a structured traceback (a list) to a string."""
         return '\n'.join(stb)
 
     def text(self, etype, value, tb, tb_offset=None, context=5):
         """Return formatted traceback.
 
         Subclasses may override this if they add extra arguments.
         """
         tb_list = self.structured_traceback(etype, value, tb,
                                             tb_offset, context)
         return self.stb2text(tb_list)
 
     def structured_traceback(self, etype, evalue, tb, tb_offset=None,
                              context=5, mode=None):
         """Return a list of traceback frames.
 
         Must be implemented by each class.
         """
         raise NotImplementedError()
 
 
 #---------------------------------------------------------------------------
 class ListTB(TBTools):
     """Print traceback information from a traceback list, with optional color.
 
     Calling requires 3 arguments: (etype, evalue, elist)
     as would be obtained by::
     
       etype, evalue, tb = sys.exc_info()
       if tb:
         elist = traceback.extract_tb(tb)
       else:
         elist = None
 
     It can thus be used by programs which need to process the traceback before
     printing (such as console replacements based on the code module from the
     standard library).
 
     Because they are meant to be called without a full traceback (only a
     list), instances of this class can't call the interactive pdb debugger."""
 
     def __init__(self, color_scheme='NoColor', call_pdb=False, ostream=None, parent=None, config=None):
         TBTools.__init__(self, color_scheme=color_scheme, call_pdb=call_pdb,
                          ostream=ostream, parent=parent,config=config)
 
     def __call__(self, etype, value, elist):
         self.ostream.flush()
         self.ostream.write(self.text(etype, value, elist))
         self.ostream.write('\n')
 
     def structured_traceback(self, etype, value, elist, tb_offset=None,
                              context=5):
         """Return a color formatted string with the traceback info.
 
         Parameters
         ----------
         etype : exception type
           Type of the exception raised.
 
         value : object
           Data stored in the exception
 
         elist : list
           List of frames, see class docstring for details.
 
         tb_offset : int, optional
           Number of frames in the traceback to skip.  If not given, the
           instance value is used (set in constructor).
 
         context : int, optional
           Number of lines of context information to print.
 
         Returns
         -------
         String with formatted exception.
         """
         tb_offset = self.tb_offset if tb_offset is None else tb_offset
         Colors = self.Colors
         out_list = []
         if elist:
 
             if tb_offset and len(elist) > tb_offset:
                 elist = elist[tb_offset:]
 
             out_list.append('Traceback %s(most recent call last)%s:' %
                             (Colors.normalEm, Colors.Normal) + '\n')
             out_list.extend(self._format_list(elist))
         # The exception info should be a single entry in the list.
         lines = ''.join(self._format_exception_only(etype, value))
         out_list.append(lines)
 
         # Note: this code originally read:
 
         ## for line in lines[:-1]:
         ##     out_list.append(" "+line)
         ## out_list.append(lines[-1])
 
         # This means it was indenting everything but the last line by a little
         # bit.  I've disabled this for now, but if we see ugliness somewhere we
         # can restore it.
 
         return out_list
 
     def _format_list(self, extracted_list):
         """Format a list of traceback entry tuples for printing.
 
         Given a list of tuples as returned by extract_tb() or
         extract_stack(), return a list of strings ready for printing.
         Each string in the resulting list corresponds to the item with the
         same index in the argument list.  Each string ends in a newline;
         the strings may contain internal newlines as well, for those items
         whose source text line is not None.
 
         Lifted almost verbatim from traceback.py
         """
 
         Colors = self.Colors
         list = []
         for filename, lineno, name, line in extracted_list[:-1]:
             item = '  File %s"%s"%s, line %s%d%s, in %s%s%s\n' % \
                    (Colors.filename, py3compat.cast_unicode_py2(filename, "utf-8"), Colors.Normal,
                     Colors.lineno, lineno, Colors.Normal,
                     Colors.name, py3compat.cast_unicode_py2(name, "utf-8"), Colors.Normal)
             if line:
                 item += '    %s\n' % line.strip()
             list.append(item)
         # Emphasize the last entry
         filename, lineno, name, line = extracted_list[-1]
         item = '%s  File %s"%s"%s, line %s%d%s, in %s%s%s%s\n' % \
                (Colors.normalEm,
                 Colors.filenameEm, py3compat.cast_unicode_py2(filename, "utf-8"), Colors.normalEm,
                 Colors.linenoEm, lineno, Colors.normalEm,
                 Colors.nameEm, py3compat.cast_unicode_py2(name, "utf-8"), Colors.normalEm,
                 Colors.Normal)
         if line:
             item += '%s    %s%s\n' % (Colors.line, line.strip(),
                                       Colors.Normal)
         list.append(item)
         return list
 
     def _format_exception_only(self, etype, value):
         """Format the exception part of a traceback.
 
         The arguments are the exception type and value such as given by
         sys.exc_info()[:2]. The return value is a list of strings, each ending
         in a newline.  Normally, the list contains a single string; however,
         for SyntaxError exceptions, it contains several lines that (when
         printed) display detailed information about where the syntax error
         occurred.  The message indicating which exception occurred is the
         always last string in the list.
 
         Also lifted nearly verbatim from traceback.py
         """
         have_filedata = False
         Colors = self.Colors
         list = []
         stype = py3compat.cast_unicode(Colors.excName + etype.__name__ + Colors.Normal)
         if value is None:
             # Not sure if this can still happen in Python 2.6 and above
             list.append(stype + '\n')
         else:
             if issubclass(etype, SyntaxError):
                 have_filedata = True
                 if not value.filename: value.filename = "<string>"
                 if value.lineno:
                     lineno = value.lineno
                     textline = ulinecache.getline(value.filename, value.lineno)
                 else:
                     lineno = 'unknown'
                     textline = ''
                 list.append('%s  File %s"%s"%s, line %s%s%s\n' % \
                             (Colors.normalEm,
                              Colors.filenameEm, py3compat.cast_unicode(value.filename), Colors.normalEm,
                              Colors.linenoEm, lineno, Colors.Normal  ))
                 if textline == '':
                     textline = py3compat.cast_unicode(value.text, "utf-8")
 
                 if textline is not None:
                     i = 0
                     while i < len(textline) and textline[i].isspace():
                         i += 1
                     list.append('%s    %s%s\n' % (Colors.line,
                                                   textline.strip(),
                                                   Colors.Normal))
                     if value.offset is not None:
                         s = '    '
                         for c in textline[i:value.offset - 1]:
                             if c.isspace():
                                 s += c
                             else:
                                 s += ' '
                         list.append('%s%s^%s\n' % (Colors.caret, s,
                                                    Colors.Normal))
 
             try:
                 s = value.msg
             except Exception:
                 s = self._some_str(value)
             if s:
                 list.append('%s%s:%s %s\n' % (stype, Colors.excName,
                                               Colors.Normal, s))
             else:
                 list.append('%s\n' % stype)
 
         # sync with user hooks
         if have_filedata:
             ipinst = get_ipython()
             if ipinst is not None:
                 ipinst.hooks.synchronize_with_editor(value.filename, value.lineno, 0)
 
         return list
 
     def get_exception_only(self, etype, value):
         """Only print the exception type and message, without a traceback.
 
         Parameters
         ----------
         etype : exception type
         value : exception value
         """
         return ListTB.structured_traceback(self, etype, value, [])
 
     def show_exception_only(self, etype, evalue):
         """Only print the exception type and message, without a traceback.
 
         Parameters
         ----------
         etype : exception type
         value : exception value
         """
         # This method needs to use __call__ from *this* class, not the one from
         # a subclass whose signature or behavior may be different
         ostream = self.ostream
         ostream.flush()
         ostream.write('\n'.join(self.get_exception_only(etype, evalue)))
         ostream.flush()
 
     def _some_str(self, value):
         # Lifted from traceback.py
         try:
             return py3compat.cast_unicode(str(value))
         except:
             return u'<unprintable %s object>' % type(value).__name__
 
 
 #----------------------------------------------------------------------------
 class VerboseTB(TBTools):
     """A port of Ka-Ping Yee's cgitb.py module that outputs color text instead
     of HTML.  Requires inspect and pydoc.  Crazy, man.
 
     Modified version which optionally strips the topmost entries from the
     traceback, to be used with alternate interpreters (because their own code
     would appear in the traceback)."""
 
     def __init__(self, color_scheme='Linux', call_pdb=False, ostream=None,
                  tb_offset=0, long_header=False, include_vars=True,
                  check_cache=None, debugger_cls = None,
                  parent=None, config=None):
         """Specify traceback offset, headers and color scheme.
 
         Define how many frames to drop from the tracebacks. Calling it with
         tb_offset=1 allows use of this handler in interpreters which will have
         their own code at the top of the traceback (VerboseTB will first
         remove that frame before printing the traceback info)."""
         TBTools.__init__(self, color_scheme=color_scheme, call_pdb=call_pdb,
                          ostream=ostream, parent=parent, config=config)
         self.tb_offset = tb_offset
         self.long_header = long_header
         self.include_vars = include_vars
         # By default we use linecache.checkcache, but the user can provide a
         # different check_cache implementation.  This is used by the IPython
         # kernel to provide tracebacks for interactive code that is cached,
         # by a compiler instance that flushes the linecache but preserves its
         # own code cache.
         if check_cache is None:
             check_cache = linecache.checkcache
         self.check_cache = check_cache
 
         self.debugger_cls = debugger_cls or debugger.Pdb
 
     def format_records(self, records, last_unique, recursion_repeat):
         """Format the stack frames of the traceback"""
         frames = []
         for r in records[:last_unique+recursion_repeat+1]:
             #print '*** record:',file,lnum,func,lines,index  # dbg
             frames.append(self.format_record(*r))
 
         if recursion_repeat:
             frames.append('... last %d frames repeated, from the frame below ...\n' % recursion_repeat)
             frames.append(self.format_record(*records[last_unique+recursion_repeat+1]))
 
         return frames
 
     def format_record(self, frame, file, lnum, func, lines, index):
         """Format a single stack frame"""
         Colors = self.Colors  # just a shorthand + quicker name lookup
         ColorsNormal = Colors.Normal  # used a lot
         col_scheme = self.color_scheme_table.active_scheme_name
         indent = ' ' * INDENT_SIZE
         em_normal = '%s\n%s%s' % (Colors.valEm, indent, ColorsNormal)
         undefined = '%sundefined%s' % (Colors.em, ColorsNormal)
         tpl_link = '%s%%s%s' % (Colors.filenameEm, ColorsNormal)
         tpl_call = 'in %s%%s%s%%s%s' % (Colors.vName, Colors.valEm,
                                         ColorsNormal)
         tpl_call_fail = 'in %s%%s%s(***failed resolving arguments***)%s' % \
                         (Colors.vName, Colors.valEm, ColorsNormal)
         tpl_local_var = '%s%%s%s' % (Colors.vName, ColorsNormal)
         tpl_global_var = '%sglobal%s %s%%s%s' % (Colors.em, ColorsNormal,
                                                  Colors.vName, ColorsNormal)
         tpl_name_val = '%%s %s= %%s%s' % (Colors.valEm, ColorsNormal)
 
         tpl_line = '%s%%s%s %%s' % (Colors.lineno, ColorsNormal)
         tpl_line_em = '%s%%s%s %%s%s' % (Colors.linenoEm, Colors.line,
                                          ColorsNormal)
 
         abspath = os.path.abspath
 
 
         if not file:
             file = '?'
         elif file.startswith(str("<")) and file.endswith(str(">")):
             # Not a real filename, no problem...
             pass
         elif not os.path.isabs(file):
             # Try to make the filename absolute by trying all
             # sys.path entries (which is also what linecache does)
             for dirname in sys.path:
                 try:
                     fullname = os.path.join(dirname, file)
                     if os.path.isfile(fullname):
                         file = os.path.abspath(fullname)
                         break
                 except Exception:
                     # Just in case that sys.path contains very
                     # strange entries...
                     pass
 
         file = py3compat.cast_unicode(file, util_path.fs_encoding)
         link = tpl_link % file
         args, varargs, varkw, locals = fixed_getargvalues(frame)
 
         if func == '?':
             call = ''
         else:
             # Decide whether to include variable details or not
             var_repr = self.include_vars and eqrepr or nullrepr
             try:
                 call = tpl_call % (func, inspect.formatargvalues(args,
                                                                  varargs, varkw,
                                                                  locals, formatvalue=var_repr))
             except KeyError:
                 # This happens in situations like errors inside generator
                 # expressions, where local variables are listed in the
                 # line, but can't be extracted from the frame.  I'm not
                 # 100% sure this isn't actually a bug in inspect itself,
                 # but since there's no info for us to compute with, the
                 # best we can do is report the failure and move on.  Here
                 # we must *not* call any traceback construction again,
                 # because that would mess up use of %debug later on.  So we
                 # simply report the failure and move on.  The only
                 # limitation will be that this frame won't have locals
                 # listed in the call signature.  Quite subtle problem...
                 # I can't think of a good way to validate this in a unit
                 # test, but running a script consisting of:
                 #  dict( (k,v.strip()) for (k,v) in range(10) )
                 # will illustrate the error, if this exception catch is
                 # disabled.
                 call = tpl_call_fail % func
 
         # Don't attempt to tokenize binary files.
         if file.endswith(('.so', '.pyd', '.dll')):
             return '%s %s\n' % (link, call)
 
         elif file.endswith(('.pyc', '.pyo')):
             # Look up the corresponding source file.
             try:
                 file = openpy.source_from_cache(file)
             except ValueError:
                 # Failed to get the source file for some reason
                 # E.g. https://github.com/ipython/ipython/issues/9486
                 return '%s %s\n' % (link, call)
 
         def linereader(file=file, lnum=[lnum], getline=ulinecache.getline):
             line = getline(file, lnum[0])
             lnum[0] += 1
             return line
 
         # Build the list of names on this line of code where the exception
         # occurred.
         try:
             names = []
             name_cont = False
 
             for token_type, token, start, end, line in generate_tokens(linereader):
                 # build composite names
                 if token_type == tokenize.NAME and token not in keyword.kwlist:
                     if name_cont:
                         # Continuation of a dotted name
                         try:
                             names[-1].append(token)
                         except IndexError:
                             names.append([token])
                         name_cont = False
                     else:
                         # Regular new names.  We append everything, the caller
                         # will be responsible for pruning the list later.  It's
                         # very tricky to try to prune as we go, b/c composite
                         # names can fool us.  The pruning at the end is easy
                         # to do (or the caller can print a list with repeated
                         # names if so desired.
                         names.append([token])
                 elif token == '.':
                     name_cont = True
                 elif token_type == tokenize.NEWLINE:
                     break
 
         except (IndexError, UnicodeDecodeError, SyntaxError):
             # signals exit of tokenizer
             # SyntaxError can occur if the file is not actually Python
             #  - see gh-6300
             pass
         except tokenize.TokenError as msg:
             _m = ("An unexpected error occurred while tokenizing input\n"
                   "The following traceback may be corrupted or invalid\n"
                   "The error message is: %s\n" % msg)
             error(_m)
 
         # Join composite names (e.g. "dict.fromkeys")
         names = ['.'.join(n) for n in names]
         # prune names list of duplicates, but keep the right order
         unique_names = uniq_stable(names)
 
         # Start loop over vars
         lvals = []
         if self.include_vars:
             for name_full in unique_names:
                 name_base = name_full.split('.', 1)[0]
                 if name_base in frame.f_code.co_varnames:
                     if name_base in locals:
                         try:
                             value = repr(eval(name_full, locals))
                         except:
                             value = undefined
                     else:
                         value = undefined
                     name = tpl_local_var % name_full
                 else:
                     if name_base in frame.f_globals:
                         try:
                             value = repr(eval(name_full, frame.f_globals))
                         except:
                             value = undefined
                     else:
                         value = undefined
                     name = tpl_global_var % name_full
                 lvals.append(tpl_name_val % (name, value))
         if lvals:
             lvals = '%s%s' % (indent, em_normal.join(lvals))
         else:
             lvals = ''
 
         level = '%s %s\n' % (link, call)
 
         if index is None:
             return level
         else:
             _line_format = PyColorize.Parser(style=col_scheme, parent=self).format2
             return '%s%s' % (level, ''.join(
                 _format_traceback_lines(lnum, index, lines, Colors, lvals,
                                          _line_format)))
 
     def prepare_chained_exception_message(self, cause):
         direct_cause = "\nThe above exception was the direct cause of the following exception:\n"
         exception_during_handling = "\nDuring handling of the above exception, another exception occurred:\n"
 
         if cause:
             message = [[direct_cause]]
         else:
             message = [[exception_during_handling]]
         return message
 
     def prepare_header(self, etype, long_version=False):
         colors = self.Colors  # just a shorthand + quicker name lookup
         colorsnormal = colors.Normal  # used a lot
         exc = '%s%s%s' % (colors.excName, etype, colorsnormal)
         width = min(75, get_terminal_size()[0])
         if long_version:
             # Header with the exception type, python version, and date
             pyver = 'Python ' + sys.version.split()[0] + ': ' + sys.executable
             date = time.ctime(time.time())
 
             head = '%s%s%s\n%s%s%s\n%s' % (colors.topline, '-' * width, colorsnormal,
                                            exc, ' ' * (width - len(str(etype)) - len(pyver)),
                                            pyver, date.rjust(width) )
             head += "\nA problem occurred executing Python code.  Here is the sequence of function" \
                     "\ncalls leading up to the error, with the most recent (innermost) call last."
         else:
             # Simplified header
             head = '%s%s' % (exc, 'Traceback (most recent call last)'. \
                              rjust(width - len(str(etype))) )
 
         return head
 
     def format_exception(self, etype, evalue):
         colors = self.Colors  # just a shorthand + quicker name lookup
         colorsnormal = colors.Normal  # used a lot
         indent = ' ' * INDENT_SIZE
         # Get (safely) a string form of the exception info
         try:
             etype_str, evalue_str = map(str, (etype, evalue))
         except:
             # User exception is improperly defined.
             etype, evalue = str, sys.exc_info()[:2]
             etype_str, evalue_str = map(str, (etype, evalue))
         # ... and format it
-        exception = ['%s%s%s: %s' % (colors.excName, etype_str,
-                                     colorsnormal, py3compat.cast_unicode(evalue_str))]
-
-        if (not py3compat.PY3) and type(evalue) is types.InstanceType:
-            try:
-                names = [w for w in dir(evalue) if isinstance(w, str)]
-            except:
-                # Every now and then, an object with funny internals blows up
-                # when dir() is called on it.  We do the best we can to report
-                # the problem and continue
-                _m = '%sException reporting error (object with broken dir())%s:'
-                exception.append(_m % (colors.excName, colorsnormal))
-                etype_str, evalue_str = map(str, sys.exc_info()[:2])
-                exception.append('%s%s%s: %s' % (colors.excName, etype_str,
-                                                 colorsnormal, py3compat.cast_unicode(evalue_str)))
-                names = []
-            for name in names:
-                value = text_repr(getattr(evalue, name))
-                exception.append('\n%s%s = %s' % (indent, name, value))
-
-        return exception
+        return ['%s%s%s: %s' % (colors.excName, etype_str,
+                                colorsnormal, py3compat.cast_unicode(evalue_str))]
 
     def format_exception_as_a_whole(self, etype, evalue, etb, number_of_lines_of_context, tb_offset):
         """Formats the header, traceback and exception message for a single exception.
 
         This may be called multiple times by Python 3 exception chaining
         (PEP 3134).
         """
         # some locals
         orig_etype = etype
         try:
             etype = etype.__name__
         except AttributeError:
             pass
 
         tb_offset = self.tb_offset if tb_offset is None else tb_offset
         head = self.prepare_header(etype, self.long_header)
         records = self.get_records(etb, number_of_lines_of_context, tb_offset)
 
         if records is None:
             return ""
 
         last_unique, recursion_repeat = find_recursion(orig_etype, evalue, records)
 
         frames = self.format_records(records, last_unique, recursion_repeat)
 
         formatted_exception = self.format_exception(etype, evalue)
         if records:
             filepath, lnum = records[-1][1:3]
             filepath = os.path.abspath(filepath)
             ipinst = get_ipython()
             if ipinst is not None:
                 ipinst.hooks.synchronize_with_editor(filepath, lnum, 0)
 
         return [[head] + frames + [''.join(formatted_exception[0])]]
 
     def get_records(self, etb, number_of_lines_of_context, tb_offset):
         try:
             # Try the default getinnerframes and Alex's: Alex's fixes some
             # problems, but it generates empty tracebacks for console errors
             # (5 blanks lines) where none should be returned.
             return _fixed_getinnerframes(etb, number_of_lines_of_context, tb_offset)
         except UnicodeDecodeError:
             # This can occur if a file's encoding magic comment is wrong.
             # I can't see a way to recover without duplicating a bunch of code
             # from the stdlib traceback module. --TK
             error('\nUnicodeDecodeError while processing traceback.\n')
             return None
         except:
             # FIXME: I've been getting many crash reports from python 2.3
             # users, traceable to inspect.py.  If I can find a small test-case
             # to reproduce this, I should either write a better workaround or
             # file a bug report against inspect (if that's the real problem).
             # So far, I haven't been able to find an isolated example to
             # reproduce the problem.
             inspect_error()
             traceback.print_exc(file=self.ostream)
             info('\nUnfortunately, your original traceback can not be constructed.\n')
             return None
 
     def get_parts_of_chained_exception(self, evalue):
         def get_chained_exception(exception_value):
             cause = getattr(exception_value, '__cause__', None)
             if cause:
                 return cause
             if getattr(exception_value, '__suppress_context__', False):
                 return None
             return getattr(exception_value, '__context__', None)
 
         chained_evalue = get_chained_exception(evalue)
 
         if chained_evalue:
             return chained_evalue.__class__, chained_evalue, chained_evalue.__traceback__
 
     def structured_traceback(self, etype, evalue, etb, tb_offset=None,
                              number_of_lines_of_context=5):
         """Return a nice text document describing the traceback."""
 
         formatted_exception = self.format_exception_as_a_whole(etype, evalue, etb, number_of_lines_of_context,
                                                                tb_offset)
 
         colors = self.Colors  # just a shorthand + quicker name lookup
         colorsnormal = colors.Normal  # used a lot
         head = '%s%s%s' % (colors.topline, '-' * min(75, get_terminal_size()[0]), colorsnormal)
         structured_traceback_parts = [head]
         if py3compat.PY3:
             chained_exceptions_tb_offset = 0
             lines_of_context = 3
             formatted_exceptions = formatted_exception
             exception = self.get_parts_of_chained_exception(evalue)
             if exception:
                 formatted_exceptions += self.prepare_chained_exception_message(evalue.__cause__)
                 etype, evalue, etb = exception
             else:
                 evalue = None
             chained_exc_ids = set()
             while evalue:
                 formatted_exceptions += self.format_exception_as_a_whole(etype, evalue, etb, lines_of_context,
                                                                          chained_exceptions_tb_offset)
                 exception = self.get_parts_of_chained_exception(evalue)
 
                 if exception and not id(exception[1]) in chained_exc_ids:
                     chained_exc_ids.add(id(exception[1])) # trace exception to avoid infinite 'cause' loop
                     formatted_exceptions += self.prepare_chained_exception_message(evalue.__cause__)
                     etype, evalue, etb = exception
                 else:
                     evalue = None
 
             # we want to see exceptions in a reversed order:
             # the first exception should be on top
             for formatted_exception in reversed(formatted_exceptions):
                 structured_traceback_parts += formatted_exception
         else:
             structured_traceback_parts += formatted_exception[0]
 
         return structured_traceback_parts
 
     def debugger(self, force=False):
         """Call up the pdb debugger if desired, always clean up the tb
         reference.
 
         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 the call_pdb flag is set, the pdb interactive debugger is
         invoked. In all cases, the self.tb reference to the current traceback
         is deleted to prevent lingering references which hamper memory
         management.
 
         Note that each call to pdb() does an 'import readline', so if your app
         requires a special setup for the readline completers, you'll have to
         fix that by hand after invoking the exception handler."""
 
         if force or self.call_pdb:
             if self.pdb is None:
                 self.pdb = self.debugger_cls()
             # the system displayhook may have changed, restore the original
             # for pdb
             display_trap = DisplayTrap(hook=sys.__displayhook__)
             with display_trap:
                 self.pdb.reset()
                 # Find the right frame so we don't pop up inside ipython itself
                 if hasattr(self, 'tb') and self.tb is not None:
                     etb = self.tb
                 else:
                     etb = self.tb = sys.last_traceback
                 while self.tb is not None and self.tb.tb_next is not None:
                     self.tb = self.tb.tb_next
                 if etb and etb.tb_next:
                     etb = etb.tb_next
                 self.pdb.botframe = etb.tb_frame
                 self.pdb.interaction(self.tb.tb_frame, self.tb)
 
         if hasattr(self, 'tb'):
             del self.tb
 
     def handler(self, info=None):
         (etype, evalue, etb) = info or sys.exc_info()
         self.tb = etb
         ostream = self.ostream
         ostream.flush()
         ostream.write(self.text(etype, evalue, etb))
         ostream.write('\n')
         ostream.flush()
 
     # Changed so an instance can just be called as VerboseTB_inst() and print
     # out the right info on its own.
     def __call__(self, etype=None, evalue=None, etb=None):
         """This hook can replace sys.excepthook (for Python 2.1 or higher)."""
         if etb is None:
             self.handler()
         else:
             self.handler((etype, evalue, etb))
         try:
             self.debugger()
         except KeyboardInterrupt:
             print("\nKeyboardInterrupt")
 
 
 #----------------------------------------------------------------------------
 class FormattedTB(VerboseTB, ListTB):
     """Subclass ListTB but allow calling with a traceback.
 
     It can thus be used as a sys.excepthook for Python > 2.1.
 
     Also adds 'Context' and 'Verbose' modes, not available in ListTB.
 
     Allows a tb_offset to be specified. This is useful for situations where
     one needs to remove a number of topmost frames from the traceback (such as
     occurs with python programs that themselves execute other python code,
     like Python shells).  """
 
     def __init__(self, mode='Plain', color_scheme='Linux', call_pdb=False,
                  ostream=None,
                  tb_offset=0, long_header=False, include_vars=False,
                  check_cache=None, debugger_cls=None,
                  parent=None, config=None):
 
         # NEVER change the order of this list. Put new modes at the end:
         self.valid_modes = ['Plain', 'Context', 'Verbose']
         self.verbose_modes = self.valid_modes[1:3]
 
         VerboseTB.__init__(self, color_scheme=color_scheme, call_pdb=call_pdb,
                            ostream=ostream, tb_offset=tb_offset,
                            long_header=long_header, include_vars=include_vars,
                            check_cache=check_cache, debugger_cls=debugger_cls,
                            parent=parent, config=config)
 
         # Different types of tracebacks are joined with different separators to
         # form a single string.  They are taken from this dict
         self._join_chars = dict(Plain='', Context='\n', Verbose='\n')
         # set_mode also sets the tb_join_char attribute
         self.set_mode(mode)
 
     def _extract_tb(self, tb):
         if tb:
             return traceback.extract_tb(tb)
         else:
             return None
 
     def structured_traceback(self, etype, value, tb, tb_offset=None, number_of_lines_of_context=5):
         tb_offset = self.tb_offset if tb_offset is None else tb_offset
         mode = self.mode
         if mode in self.verbose_modes:
             # Verbose modes need a full traceback
             return VerboseTB.structured_traceback(
                 self, etype, value, tb, tb_offset, number_of_lines_of_context
             )
         else:
             # We must check the source cache because otherwise we can print
             # out-of-date source code.
             self.check_cache()
             # Now we can extract and format the exception
             elist = self._extract_tb(tb)
             return ListTB.structured_traceback(
                 self, etype, value, elist, tb_offset, number_of_lines_of_context
             )
 
     def stb2text(self, stb):
         """Convert a structured traceback (a list) to a string."""
         return self.tb_join_char.join(stb)
 
 
     def set_mode(self, mode=None):
         """Switch to the desired mode.
 
         If mode is not specified, cycles through the available modes."""
 
         if not mode:
             new_idx = (self.valid_modes.index(self.mode) + 1 ) % \
                       len(self.valid_modes)
             self.mode = self.valid_modes[new_idx]
         elif mode not in self.valid_modes:
             raise ValueError('Unrecognized mode in FormattedTB: <' + mode + '>\n'
                                                                             'Valid modes: ' + str(self.valid_modes))
         else:
             self.mode = mode
         # include variable details only in 'Verbose' mode
         self.include_vars = (self.mode == self.valid_modes[2])
         # Set the join character for generating text tracebacks
         self.tb_join_char = self._join_chars[self.mode]
 
     # some convenient shortcuts
     def plain(self):
         self.set_mode(self.valid_modes[0])
 
     def context(self):
         self.set_mode(self.valid_modes[1])
 
     def verbose(self):
         self.set_mode(self.valid_modes[2])
 
 
 #----------------------------------------------------------------------------
 class AutoFormattedTB(FormattedTB):
     """A traceback printer which can be called on the fly.
 
     It will find out about exceptions by itself.
 
     A brief example::
 
         AutoTB = AutoFormattedTB(mode = 'Verbose',color_scheme='Linux')
         try:
           ...
         except:
           AutoTB()  # or AutoTB(out=logfile) where logfile is an open file object
     """
 
     def __call__(self, etype=None, evalue=None, etb=None,
                  out=None, tb_offset=None):
         """Print out a formatted exception traceback.
 
         Optional arguments:
           - out: an open file-like object to direct output to.
 
           - tb_offset: the number of frames to skip over in the stack, on a
           per-call basis (this overrides temporarily the instance's tb_offset
           given at initialization time.  """
 
         if out is None:
             out = self.ostream
         out.flush()
         out.write(self.text(etype, evalue, etb, tb_offset))
         out.write('\n')
         out.flush()
         # FIXME: we should remove the auto pdb behavior from here and leave
         # that to the clients.
         try:
             self.debugger()
         except KeyboardInterrupt:
             print("\nKeyboardInterrupt")
 
     def structured_traceback(self, etype=None, value=None, tb=None,
                              tb_offset=None, number_of_lines_of_context=5):
         if etype is None:
             etype, value, tb = sys.exc_info()
         self.tb = tb
         return FormattedTB.structured_traceback(
             self, etype, value, tb, tb_offset, number_of_lines_of_context)
 
 
 #---------------------------------------------------------------------------
 
 # A simple class to preserve Nathan's original functionality.
 class ColorTB(FormattedTB):
     """Shorthand to initialize a FormattedTB in Linux colors mode."""
 
     def __init__(self, color_scheme='Linux', call_pdb=0, **kwargs):
         FormattedTB.__init__(self, color_scheme=color_scheme,
                              call_pdb=call_pdb, **kwargs)
 
 
 class SyntaxTB(ListTB):
     """Extension which holds some state: the last exception value"""
 
     def __init__(self, color_scheme='NoColor', parent=None, config=None):
         ListTB.__init__(self, color_scheme, parent=parent, config=config)
         self.last_syntax_error = None
 
     def __call__(self, etype, value, elist):
         self.last_syntax_error = value
 
         ListTB.__call__(self, etype, value, elist)
 
     def structured_traceback(self, etype, value, elist, tb_offset=None,
                              context=5):
         # If the source file has been edited, the line in the syntax error can
         # be wrong (retrieved from an outdated cache). This replaces it with
         # the current value.
         if isinstance(value, SyntaxError) \
                 and isinstance(value.filename, str) \
                 and isinstance(value.lineno, int):
             linecache.checkcache(value.filename)
             newtext = ulinecache.getline(value.filename, value.lineno)
             if newtext:
                 value.text = newtext
         self.last_syntax_error = value
         return super(SyntaxTB, self).structured_traceback(etype, value, elist,
                                                           tb_offset=tb_offset, context=context)
 
     def clear_err_state(self):
         """Return the current error state and clear it"""
         e = self.last_syntax_error
         self.last_syntax_error = None
         return e
 
     def stb2text(self, stb):
         """Convert a structured traceback (a list) to a string."""
         return ''.join(stb)
 
 
 # some internal-use functions
 def text_repr(value):
     """Hopefully pretty robust repr equivalent."""
     # this is pretty horrible but should always return *something*
     try:
         return pydoc.text.repr(value)
     except KeyboardInterrupt:
         raise
     except:
         try:
             return repr(value)
         except KeyboardInterrupt:
             raise
         except:
             try:
                 # all still in an except block so we catch
                 # getattr raising
                 name = getattr(value, '__name__', None)
                 if name:
                     # ick, recursion
                     return text_repr(name)
                 klass = getattr(value, '__class__', None)
                 if klass:
                     return '%s instance' % text_repr(klass)
             except KeyboardInterrupt:
                 raise
             except:
                 return 'UNRECOVERABLE REPR FAILURE'
 
 
 def eqrepr(value, repr=text_repr):
     return '=%s' % repr(value)
 
 
 def nullrepr(value, repr=text_repr):
     return ''

IPython/extensions/autoreload.py

@@ -1,532 +1,528 b''
 """IPython extension to reload modules before executing user code.
 
 ``autoreload`` reloads modules automatically before entering the execution of
 code typed at the IPython prompt.
 
 This makes for example the following workflow possible:
 
 .. sourcecode:: ipython
 
    In [1]: %load_ext autoreload
 
    In [2]: %autoreload 2
 
    In [3]: from foo import some_function
 
    In [4]: some_function()
    Out[4]: 42
 
    In [5]: # open foo.py in an editor and change some_function to return 43
 
    In [6]: some_function()
    Out[6]: 43
 
 The module was reloaded without reloading it explicitly, and the object
 imported with ``from foo import ...`` was also updated.
 
 Usage
 =====
 
 The following magic commands are provided:
 
 ``%autoreload``
 
     Reload all modules (except those excluded by ``%aimport``)
     automatically now.
 
 ``%autoreload 0``
 
     Disable automatic reloading.
 
 ``%autoreload 1``
 
     Reload all modules imported with ``%aimport`` every time before
     executing the Python code typed.
 
 ``%autoreload 2``
 
     Reload all modules (except those excluded by ``%aimport``) every
     time before executing the Python code typed.
 
 ``%aimport``
 
     List modules which are to be automatically imported or not to be imported.
 
 ``%aimport foo``
 
     Import module 'foo' and mark it to be autoreloaded for ``%autoreload 1``
 
 ``%aimport foo, bar``
 
     Import modules 'foo', 'bar' and mark them to be autoreloaded for ``%autoreload 1``
 
 ``%aimport -foo``
 
     Mark module 'foo' to not be autoreloaded.
 
 Caveats
 =======
 
 Reloading Python modules in a reliable way is in general difficult,
 and unexpected things may occur. ``%autoreload`` tries to work around
 common pitfalls by replacing function code objects and parts of
 classes previously in the module with new versions. This makes the
 following things to work:
 
 - Functions and classes imported via 'from xxx import foo' are upgraded
   to new versions when 'xxx' is reloaded.
 
 - Methods and properties of classes are upgraded on reload, so that
   calling 'c.foo()' on an object 'c' created before the reload causes
   the new code for 'foo' to be executed.
 
 Some of the known remaining caveats are:
 
 - Replacing code objects does not always succeed: changing a @property
   in a class to an ordinary method or a method to a member variable
   can cause problems (but in old objects only).
 
 - Functions that are removed (eg. via monkey-patching) from a module
   before it is reloaded are not upgraded.
 
 - C extension modules cannot be reloaded, and so cannot be autoreloaded.
 """
 
 skip_doctest = True
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2000 Thomas Heller
 #  Copyright (C) 2008 Pauli Virtanen <[e-mail]>
 #  Copyright (C) 2012  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.
 #-----------------------------------------------------------------------------
 #
 # This IPython module is written by Pauli Virtanen, based on the autoreload
 # code by Thomas Heller.
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import os
 import sys
 import traceback
 import types
 import weakref
 from importlib import import_module
-
+from IPython.utils.py3compat import PY3
 try:
     # Reload is not defined by default in Python3.
     reload
 except NameError:
     from imp import reload
 
 from IPython.utils import openpy
-from IPython.utils.py3compat import PY3
 
 #------------------------------------------------------------------------------
 # Autoreload functionality
 #------------------------------------------------------------------------------
 
 class ModuleReloader(object):
     enabled = False
     """Whether this reloader is enabled"""
 
     check_all = True
     """Autoreload all modules, not just those listed in 'modules'"""
 
     def __init__(self):
         # Modules that failed to reload: {module: mtime-on-failed-reload, ...}
         self.failed = {}
         # Modules specially marked as autoreloadable.
         self.modules = {}
         # Modules specially marked as not autoreloadable.
         self.skip_modules = {}
         # (module-name, name) -> weakref, for replacing old code objects
         self.old_objects = {}
         # Module modification timestamps
         self.modules_mtimes = {}
 
         # Cache module modification times
         self.check(check_all=True, do_reload=False)
 
     def mark_module_skipped(self, module_name):
         """Skip reloading the named module in the future"""
         try:
             del self.modules[module_name]
         except KeyError:
             pass
         self.skip_modules[module_name] = True
 
     def mark_module_reloadable(self, module_name):
         """Reload the named module in the future (if it is imported)"""
         try:
             del self.skip_modules[module_name]
         except KeyError:
             pass
         self.modules[module_name] = True
 
     def aimport_module(self, module_name):
         """Import a module, and mark it reloadable
 
         Returns
         -------
         top_module : module
             The imported module if it is top-level, or the top-level
         top_name : module
             Name of top_module
 
         """
         self.mark_module_reloadable(module_name)
 
         import_module(module_name)
         top_name = module_name.split('.')[0]
         top_module = sys.modules[top_name]
         return top_module, top_name
 
     def filename_and_mtime(self, module):
         if not hasattr(module, '__file__') or module.__file__ is None:
             return None, None
 
         if getattr(module, '__name__', None) == '__main__':
             # we cannot reload(__main__)
             return None, None
 
         filename = module.__file__
         path, ext = os.path.splitext(filename)
 
         if ext.lower() == '.py':
             py_filename = filename
         else:
             try:
                 py_filename = openpy.source_from_cache(filename)
             except ValueError:
                 return None, None
 
         try:
             pymtime = os.stat(py_filename).st_mtime
         except OSError:
             return None, None
 
         return py_filename, pymtime
 
     def check(self, check_all=False, do_reload=True):
         """Check whether some modules need to be reloaded."""
 
         if not self.enabled and not check_all:
             return
 
         if check_all or self.check_all:
             modules = list(sys.modules.keys())
         else:
             modules = list(self.modules.keys())
 
         for modname in modules:
             m = sys.modules.get(modname, None)
 
             if modname in self.skip_modules:
                 continue
 
             py_filename, pymtime = self.filename_and_mtime(m)
             if py_filename is None:
                 continue
 
             try:
                 if pymtime <= self.modules_mtimes[modname]:
                     continue
             except KeyError:
                 self.modules_mtimes[modname] = pymtime
                 continue
             else:
                 if self.failed.get(py_filename, None) == pymtime:
                     continue
 
             self.modules_mtimes[modname] = pymtime
 
             # If we've reached this point, we should try to reload the module
             if do_reload:
                 try:
                     superreload(m, reload, self.old_objects)
                     if py_filename in self.failed:
                         del self.failed[py_filename]
                 except:
                     print("[autoreload of %s failed: %s]" % (
                             modname, traceback.format_exc(1)), file=sys.stderr)
                     self.failed[py_filename] = pymtime
 
 #------------------------------------------------------------------------------
 # superreload
 #------------------------------------------------------------------------------
 
 
 func_attrs = ['__code__', '__defaults__', '__doc__',
               '__closure__', '__globals__', '__dict__']
 
 
 def update_function(old, new):
     """Upgrade the code object of a function"""
     for name in func_attrs:
         try:
             setattr(old, name, getattr(new, name))
         except (AttributeError, TypeError):
             pass
 
 
 def update_class(old, new):
     """Replace stuff in the __dict__ of a class, and upgrade
     method code objects"""
     for key in list(old.__dict__.keys()):
         old_obj = getattr(old, key)
 
         try:
             new_obj = getattr(new, key)
         except AttributeError:
             # obsolete attribute: remove it
             try:
                 delattr(old, key)
             except (AttributeError, TypeError):
                 pass
             continue
 
         if update_generic(old_obj, new_obj): continue
 
         try:
             setattr(old, key, getattr(new, key))
         except (AttributeError, TypeError):
             pass # skip non-writable attributes
 
 
 def update_property(old, new):
     """Replace get/set/del functions of a property"""
     update_generic(old.fdel, new.fdel)
     update_generic(old.fget, new.fget)
     update_generic(old.fset, new.fset)
 
 
 def isinstance2(a, b, typ):
     return isinstance(a, typ) and isinstance(b, typ)
 
 
 UPDATE_RULES = [
     (lambda a, b: isinstance2(a, b, type),
      update_class),
     (lambda a, b: isinstance2(a, b, types.FunctionType),
      update_function),
     (lambda a, b: isinstance2(a, b, property),
      update_property),
 ]
 UPDATE_RULES.extend([(lambda a, b: isinstance2(a, b, types.MethodType),
                       lambda a, b: update_function(a.__func__, b.__func__)),
 ])
 
 
 def update_generic(a, b):
     for type_check, update in UPDATE_RULES:
         if type_check(a, b):
             update(a, b)
             return True
     return False
 
 
 class StrongRef(object):
     def __init__(self, obj):
         self.obj = obj
     def __call__(self):
         return self.obj
 
 
 def superreload(module, reload=reload, old_objects={}):
     """Enhanced version of the builtin reload function.
 
     superreload remembers objects previously in the module, and
 
     - upgrades the class dictionary of every old class in the module
     - upgrades the code object of every old function and method
     - clears the module's namespace before reloading
 
     """
 
     # collect old objects in the module
     for name, obj in list(module.__dict__.items()):
         if not hasattr(obj, '__module__') or obj.__module__ != module.__name__:
             continue
         key = (module.__name__, name)
         try:
             old_objects.setdefault(key, []).append(weakref.ref(obj))
         except TypeError:
-            # weakref doesn't work for all types;
-            # create strong references for 'important' cases
-            if not PY3 and isinstance(obj, types.ClassType):
-                old_objects.setdefault(key, []).append(StrongRef(obj))
+            pass
 
     # reload module
     try:
         # clear namespace first from old cruft
         old_dict = module.__dict__.copy()
         old_name = module.__name__
         module.__dict__.clear()
         module.__dict__['__name__'] = old_name
         module.__dict__['__loader__'] = old_dict['__loader__']
     except (TypeError, AttributeError, KeyError):
         pass
 
     try:
         module = reload(module)
     except:
         # restore module dictionary on failed reload
         module.__dict__.update(old_dict)
         raise
 
     # iterate over all objects and update functions & classes
     for name, new_obj in list(module.__dict__.items()):
         key = (module.__name__, name)
         if key not in old_objects: continue
 
         new_refs = []
         for old_ref in old_objects[key]:
             old_obj = old_ref()
             if old_obj is None: continue
             new_refs.append(old_ref)
             update_generic(old_obj, new_obj)
 
         if new_refs:
             old_objects[key] = new_refs
         else:
             del old_objects[key]
 
     return module
 
 #------------------------------------------------------------------------------
 # IPython connectivity
 #------------------------------------------------------------------------------
 
 from IPython.core.magic import Magics, magics_class, line_magic
 
 @magics_class
 class AutoreloadMagics(Magics):
     def __init__(self, *a, **kw):
         super(AutoreloadMagics, self).__init__(*a, **kw)
         self._reloader = ModuleReloader()
         self._reloader.check_all = False
         self.loaded_modules = set(sys.modules)
 
     @line_magic
     def autoreload(self, parameter_s=''):
         r"""%autoreload => Reload modules automatically
 
         %autoreload
         Reload all modules (except those excluded by %aimport) automatically
         now.
 
         %autoreload 0
         Disable automatic reloading.
 
         %autoreload 1
         Reload all modules imported with %aimport every time before executing
         the Python code typed.
 
         %autoreload 2
         Reload all modules (except those excluded by %aimport) every time
         before executing the Python code typed.
 
         Reloading Python modules in a reliable way is in general
         difficult, and unexpected things may occur. %autoreload tries to
         work around common pitfalls by replacing function code objects and
         parts of classes previously in the module with new versions. This
         makes the following things to work:
 
         - Functions and classes imported via 'from xxx import foo' are upgraded
           to new versions when 'xxx' is reloaded.
 
         - Methods and properties of classes are upgraded on reload, so that
           calling 'c.foo()' on an object 'c' created before the reload causes
           the new code for 'foo' to be executed.
 
         Some of the known remaining caveats are:
 
         - Replacing code objects does not always succeed: changing a @property
           in a class to an ordinary method or a method to a member variable
           can cause problems (but in old objects only).
 
         - Functions that are removed (eg. via monkey-patching) from a module
           before it is reloaded are not upgraded.
 
         - C extension modules cannot be reloaded, and so cannot be
           autoreloaded.
 
         """
         if parameter_s == '':
             self._reloader.check(True)
         elif parameter_s == '0':
             self._reloader.enabled = False
         elif parameter_s == '1':
             self._reloader.check_all = False
             self._reloader.enabled = True
         elif parameter_s == '2':
             self._reloader.check_all = True
             self._reloader.enabled = True
 
     @line_magic
     def aimport(self, parameter_s='', stream=None):
         """%aimport => Import modules for automatic reloading.
 
         %aimport
         List modules to automatically import and not to import.
 
         %aimport foo
         Import module 'foo' and mark it to be autoreloaded for %autoreload 1
 
         %aimport foo, bar
         Import modules 'foo', 'bar' and mark them to be autoreloaded for %autoreload 1
 
         %aimport -foo
         Mark module 'foo' to not be autoreloaded for %autoreload 1
         """
         modname = parameter_s
         if not modname:
             to_reload = sorted(self._reloader.modules.keys())
             to_skip = sorted(self._reloader.skip_modules.keys())
             if stream is None:
                 stream = sys.stdout
             if self._reloader.check_all:
                 stream.write("Modules to reload:\nall-except-skipped\n")
             else:
                 stream.write("Modules to reload:\n%s\n" % ' '.join(to_reload))
             stream.write("\nModules to skip:\n%s\n" % ' '.join(to_skip))
         elif modname.startswith('-'):
             modname = modname[1:]
             self._reloader.mark_module_skipped(modname)
         else:
             for _module in ([_.strip() for _ in modname.split(',')]):
                 top_module, top_name = self._reloader.aimport_module(_module)
 
                 # Inject module to user namespace
                 self.shell.push({top_name: top_module})
 
     def pre_run_cell(self):
         if self._reloader.enabled:
             try:
                 self._reloader.check()
             except:
                 pass
 
     def post_execute_hook(self):
         """Cache the modification times of any modules imported in this execution
         """
         newly_loaded_modules = set(sys.modules) - self.loaded_modules
         for modname in newly_loaded_modules:
             _, pymtime = self._reloader.filename_and_mtime(sys.modules[modname])
             if pymtime is not None:
                 self._reloader.modules_mtimes[modname] = pymtime
 
         self.loaded_modules.update(newly_loaded_modules)
 
 
 def load_ipython_extension(ip):
     """Load the extension in IPython."""
     auto_reload = AutoreloadMagics(ip)
     ip.register_magics(auto_reload)
     ip.events.register('pre_run_cell', auto_reload.pre_run_cell)
     ip.events.register('post_execute', auto_reload.post_execute_hook)

IPython/utils/_process_common.py

@@ -1,223 +1,212 b''
 """Common utilities for the various process_* implementations.
 
 This file is only meant to be imported by the platform-specific implementations
 of subprocess utilities, and it contains tools that are common to all of them.
 """
 
 #-----------------------------------------------------------------------------
 #  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
 #-----------------------------------------------------------------------------
 import subprocess
 import shlex
 import sys
 import os
 
 from IPython.utils import py3compat
 
 #-----------------------------------------------------------------------------
 # Function definitions
 #-----------------------------------------------------------------------------
 
 def read_no_interrupt(p):
     """Read from a pipe ignoring EINTR errors.
 
     This is necessary because when reading from pipes with GUI event loops
     running in the background, often interrupts are raised that stop the
     command from completing."""
     import errno
 
     try:
         return p.read()
     except IOError as err:
         if err.errno != errno.EINTR:
             raise
 
 
 def process_handler(cmd, callback, stderr=subprocess.PIPE):
     """Open a command in a shell subprocess and execute a callback.
 
     This function provides common scaffolding for creating subprocess.Popen()
     calls.  It creates a Popen object and then calls the callback with it.
 
     Parameters
     ----------
     cmd : str or list
       A command to be executed by the system, using :class:`subprocess.Popen`.
       If a string is passed, it will be run in the system shell. If a list is
       passed, it will be used directly as arguments.
 
     callback : callable
       A one-argument function that will be called with the Popen object.
 
     stderr : file descriptor number, optional
       By default this is set to ``subprocess.PIPE``, but you can also pass the
       value ``subprocess.STDOUT`` to force the subprocess' stderr to go into
       the same file descriptor as its stdout.  This is useful to read stdout
       and stderr combined in the order they are generated.
 
     Returns
     -------
     The return value of the provided callback is returned.
     """
     sys.stdout.flush()
     sys.stderr.flush()
     # On win32, close_fds can't be true when using pipes for stdin/out/err
     close_fds = sys.platform != 'win32'
     # Determine if cmd should be run with system shell.
     shell = isinstance(cmd, str)
     # On POSIX systems run shell commands with user-preferred shell.
     executable = None
     if shell and os.name == 'posix' and 'SHELL' in os.environ:
         executable = os.environ['SHELL']
     p = subprocess.Popen(cmd, shell=shell,
                          executable=executable,
                          stdin=subprocess.PIPE,
                          stdout=subprocess.PIPE,
                          stderr=stderr,
                          close_fds=close_fds)
 
     try:
         out = callback(p)
     except KeyboardInterrupt:
         print('^C')
         sys.stdout.flush()
         sys.stderr.flush()
         out = None
     finally:
         # Make really sure that we don't leave processes behind, in case the
         # call above raises an exception
         # We start by assuming the subprocess finished (to avoid NameErrors
         # later depending on the path taken)
         if p.returncode is None:
             try:
                 p.terminate()
                 p.poll()
             except OSError:
                 pass
         # One last try on our way out
         if p.returncode is None:
             try:
                 p.kill()
             except OSError:
                 pass
 
     return out
 
 
 def getoutput(cmd):
     """Run a command and return its stdout/stderr as a string.
 
     Parameters
     ----------
     cmd : str or list
       A command to be executed in the system shell.
 
     Returns
     -------
     output : str
       A string containing the combination of stdout and stderr from the
     subprocess, in whatever order the subprocess originally wrote to its
     file descriptors (so the order of the information in this string is the
     correct order as would be seen if running the command in a terminal).
     """
     out = process_handler(cmd, lambda p: p.communicate()[0], subprocess.STDOUT)
     if out is None:
         return ''
     return py3compat.bytes_to_str(out)
 
 
 def getoutputerror(cmd):
     """Return (standard output, standard error) of executing cmd in a shell.
 
     Accepts the same arguments as os.system().
 
     Parameters
     ----------
     cmd : str or list
       A command to be executed in the system shell.
 
     Returns
     -------
     stdout : str
     stderr : str
     """
     return get_output_error_code(cmd)[:2]
 
 def get_output_error_code(cmd):
     """Return (standard output, standard error, return code) of executing cmd
     in a shell.
 
     Accepts the same arguments as os.system().
 
     Parameters
     ----------
     cmd : str or list
       A command to be executed in the system shell.
 
     Returns
     -------
     stdout : str
     stderr : str
     returncode: int
     """
 
     out_err, p = process_handler(cmd, lambda p: (p.communicate(), p))
     if out_err is None:
         return '', '', p.returncode
     out, err = out_err
     return py3compat.bytes_to_str(out), py3compat.bytes_to_str(err), p.returncode
 
 def arg_split(s, posix=False, strict=True):
     """Split a command line's arguments in a shell-like manner.
 
     This is a modified version of the standard library's shlex.split()
     function, but with a default of posix=False for splitting, so that quotes
     in inputs are respected.
 
     if strict=False, then any errors shlex.split would raise will result in the
     unparsed remainder being the last element of the list, rather than raising.
     This is because we sometimes use arg_split to parse things other than
     command-line args.
     """
 
-    # Unfortunately, python's shlex module is buggy with unicode input:
-    # http://bugs.python.org/issue1170
-    # At least encoding the input when it's unicode seems to help, but there
-    # may be more problems lurking.  Apparently this is fixed in python3.
-    is_unicode = False
-    if (not py3compat.PY3) and isinstance(s, unicode):
-        is_unicode = True
-        s = s.encode('utf-8')
     lex = shlex.shlex(s, posix=posix)
     lex.whitespace_split = True
     # Extract tokens, ensuring that things like leaving open quotes
     # does not cause this to raise.  This is important, because we
     # sometimes pass Python source through this (e.g. %timeit f(" ")),
     # and it shouldn't raise an exception.
     # It may be a bad idea to parse things that are not command-line args
     # through this function, but we do, so let's be safe about it.
     lex.commenters='' #fix for GH-1269
     tokens = []
     while True:
         try:
             tokens.append(next(lex))
         except StopIteration:
             break
         except ValueError:
             if strict:
                 raise
             # couldn't parse, get remaining blob as last token
             tokens.append(lex.token)
             break
-    
-    if is_unicode:
-        # Convert the tokens back to unicode.
-        tokens = [x.decode('utf-8') for x in tokens]
+
     return tokens