Fixing small bug in activate.

If the parallelmagic extension has not been loaded, activate would
get an empty list from get_component. Now get_component returns None
in that case and activate checks for None and prints a message to
the user to load the extension.

IPython/core/iplib.py

@@ -1,2486 +1,2488 b''
 # -*- coding: utf-8 -*-
 """
 Main IPython Component
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2001 Janko Hauser <[e-mail]>
 #  Copyright (C) 2001-2007 Fernando Perez. <[e-mail]>
 #  Copyright (C) 2008-2009  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 from __future__ import with_statement
 
 import __builtin__
 import StringIO
 import bdb
 import codeop
 import exceptions
 import new
 import os
 import re
 import string
 import sys
 import tempfile
 from contextlib import nested
 
 from IPython.core import ultratb
 from IPython.core import debugger, oinspect
 from IPython.core import shadowns
 from IPython.core import history as ipcorehist
 from IPython.core import prefilter
 from IPython.core.alias import AliasManager
 from IPython.core.builtin_trap import BuiltinTrap
 from IPython.core.display_trap import DisplayTrap
 from IPython.core.fakemodule import FakeModule, init_fakemod_dict
 from IPython.core.logger import Logger
 from IPython.core.magic import Magic
 from IPython.core.prompts import CachedOutput
 from IPython.core.prefilter import PrefilterManager
 from IPython.core.component import Component
 from IPython.core.usage import interactive_usage, default_banner
 from IPython.core.error import TryNext, UsageError
 
 from IPython.utils import pickleshare
 from IPython.external.Itpl import ItplNS
 from IPython.lib.backgroundjobs import BackgroundJobManager
 from IPython.utils.ipstruct import Struct
 from IPython.utils import PyColorize
 from IPython.utils.genutils import *
 from IPython.utils.genutils import get_ipython_dir
 from IPython.utils.platutils import toggle_set_term_title, set_term_title
 from IPython.utils.strdispatch import StrDispatch
 from IPython.utils.syspathcontext import prepended_to_syspath
 
 # from IPython.utils import growl
 # growl.start("IPython")
 
 from IPython.utils.traitlets import (
     Int, Str, CBool, CaselessStrEnum, Enum, List, Unicode
 )
 
 #-----------------------------------------------------------------------------
 # Globals
 #-----------------------------------------------------------------------------
 
 
 # store the builtin raw_input globally, and use this always, in case user code
 # overwrites it (like wx.py.PyShell does)
 raw_input_original = raw_input
 
 # compiled regexps for autoindent management
 dedent_re = re.compile(r'^\s+raise|^\s+return|^\s+pass')
 
 
 #-----------------------------------------------------------------------------
 # Utilities
 #-----------------------------------------------------------------------------
 
 
 ini_spaces_re = re.compile(r'^(\s+)')
 
 
 def num_ini_spaces(strng):
     """Return the number of initial spaces in a string"""
 
     ini_spaces = ini_spaces_re.match(strng)
     if ini_spaces:
         return ini_spaces.end()
     else:
         return 0
 
 
 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
 
 
 class SpaceInInput(exceptions.Exception): pass
 
 class Bunch: pass
 
 class InputList(list):
     """Class to store user input.
 
     It's basically a list, but slices return a string instead of a list, thus
     allowing things like (assuming 'In' is an instance):
 
     exec In[4:7]
 
     or
 
     exec In[5:9] + In[14] + In[21:25]"""
 
     def __getslice__(self,i,j):
         return ''.join(list.__getslice__(self,i,j))
 
 
 class SyntaxTB(ultratb.ListTB):
     """Extension which holds some state: the last exception value"""
 
     def __init__(self,color_scheme = 'NoColor'):
         ultratb.ListTB.__init__(self,color_scheme)
         self.last_syntax_error = None
 
     def __call__(self, etype, value, elist):
         self.last_syntax_error = value
         ultratb.ListTB.__call__(self,etype,value,elist)
 
     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 get_default_editor():
     try:
         ed = os.environ['EDITOR']
     except KeyError:
         if os.name == 'posix':
             ed = 'vi'  # the only one guaranteed to be there!
         else:
             ed = 'notepad' # same in Windows!
     return ed
 
 
 def get_default_colors():
     if sys.platform=='darwin':
         return "LightBG"
     elif os.name=='nt':
         return 'Linux'
     else:
         return 'Linux'
 
 
 class SeparateStr(Str):
     """A Str subclass to validate separate_in, separate_out, etc.
 
     This is a Str based traitlet that converts '0'->'' and '\\n'->'\n'.
     """
 
     def validate(self, obj, value):
         if value == '0': value = ''
         value = value.replace('\\n','\n')
         return super(SeparateStr, self).validate(obj, value)
 
 
 #-----------------------------------------------------------------------------
 # Main IPython class
 #-----------------------------------------------------------------------------
 
 
 class InteractiveShell(Component, Magic):
     """An enhanced, interactive shell for Python."""
 
     autocall = Enum((0,1,2), default_value=1, config=True)
     autoedit_syntax = CBool(False, config=True)
     autoindent = CBool(True, config=True)
     automagic = CBool(True, config=True)
     banner = Str('')
     banner1 = Str(default_banner, config=True)
     banner2 = Str('', config=True)
     cache_size = Int(1000, config=True)
     color_info = CBool(True, config=True)
     colors = CaselessStrEnum(('NoColor','LightBG','Linux'), 
                              default_value=get_default_colors(), config=True)
     confirm_exit = CBool(True, config=True)
     debug = CBool(False, config=True)
     deep_reload = CBool(False, config=True)
     # This display_banner only controls whether or not self.show_banner()
     # is called when mainloop/interact are called.  The default is False
     # because for the terminal based application, the banner behavior
     # is controlled by Global.display_banner, which IPythonApp looks at
     # to determine if *it* should call show_banner() by hand or not.
     display_banner = CBool(False) # This isn't configurable!
     embedded = CBool(False)
     embedded_active = CBool(False)
     editor = Str(get_default_editor(), config=True)
     filename = Str("<ipython console>")
     ipythondir= Unicode('', config=True) # Set to get_ipython_dir() in __init__
     logstart = CBool(False, config=True)
     logfile = Str('', config=True)
     logappend = Str('', config=True)
     object_info_string_level = Enum((0,1,2), default_value=0,
                                     config=True)
     pager = Str('less', config=True)
     pdb = CBool(False, config=True)
     pprint = CBool(True, config=True)
     profile = Str('', config=True)
     prompt_in1 = Str('In [\\#]: ', config=True)
     prompt_in2 = Str('   .\\D.: ', config=True)
     prompt_out = Str('Out[\\#]: ', config=True)
     prompts_pad_left = CBool(True, config=True)
     quiet = CBool(False, config=True)
 
     readline_use = CBool(True, config=True)
     readline_merge_completions = CBool(True, config=True)
     readline_omit__names = Enum((0,1,2), default_value=0, config=True)
     readline_remove_delims = Str('-/~', config=True)
     readline_parse_and_bind = List([
             'tab: complete',
             '"\C-l": possible-completions',
             'set show-all-if-ambiguous on',
             '"\C-o": tab-insert',
             '"\M-i": "    "',
             '"\M-o": "\d\d\d\d"',
             '"\M-I": "\d\d\d\d"',
             '"\C-r": reverse-search-history',
             '"\C-s": forward-search-history',
             '"\C-p": history-search-backward',
             '"\C-n": history-search-forward',
             '"\e[A": history-search-backward',
             '"\e[B": history-search-forward',
             '"\C-k": kill-line',
             '"\C-u": unix-line-discard',
         ], allow_none=False, config=True)
 
     screen_length = Int(0, config=True)
     
     # Use custom TraitletTypes that convert '0'->'' and '\\n'->'\n'
     separate_in = SeparateStr('\n', config=True)
     separate_out = SeparateStr('', config=True)
     separate_out2 = SeparateStr('', config=True)
 
     system_header = Str('IPython system call: ', config=True)
     system_verbose = CBool(False, config=True)
     term_title = CBool(False, config=True)
     wildcards_case_sensitive = CBool(True, config=True)
     xmode = CaselessStrEnum(('Context','Plain', 'Verbose'), 
                             default_value='Context', config=True)
 
     autoexec = List(allow_none=False)
 
     # class attribute to indicate whether the class supports threads or not.
     # Subclasses with thread support should override this as needed.
     isthreaded = False
 
     def __init__(self, parent=None, config=None, ipythondir=None, usage=None,
                  user_ns=None, user_global_ns=None,
                  banner1=None, banner2=None, display_banner=None,
                  custom_exceptions=((),None)):
 
         # This is where traitlets with a config_key argument are updated
         # from the values on config.
         super(InteractiveShell, self).__init__(parent, config=config)
 
         # These are relatively independent and stateless
         self.init_ipythondir(ipythondir)
         self.init_instance_attrs()
         self.init_term_title()
         self.init_usage(usage)
         self.init_banner(banner1, banner2, display_banner)
 
         # Create namespaces (user_ns, user_global_ns, etc.)
         self.init_create_namespaces(user_ns, user_global_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.
         self.save_sys_module_state()
         self.init_sys_modules()
 
         self.init_history()
         self.init_encoding()
         self.init_prefilter()
 
         Magic.__init__(self, self)
 
         self.init_syntax_highlighting()
         self.init_hooks()
         self.init_pushd_popd_magic()
         self.init_traceback_handlers(custom_exceptions)
         self.init_user_ns()
         self.init_logger()
         self.init_alias()
         self.init_builtins()
         
         # pre_config_initialization
         self.init_shadow_hist()
 
         # The next section should contain averything that was in ipmaker.
         self.init_logstart()
 
         # The following was in post_config_initialization
         self.init_inspector()
         self.init_readline()
         self.init_prompts()
         self.init_displayhook()
         self.init_reload_doctest()
         self.init_magics()
         self.init_pdb()
         self.hooks.late_startup_hook()
 
     def get_ipython(self):
         return self
 
     #-------------------------------------------------------------------------
     # Traitlet changed handlers
     #-------------------------------------------------------------------------
 
     def _banner1_changed(self):
         self.compute_banner()
 
     def _banner2_changed(self):
         self.compute_banner()
 
     def _ipythondir_changed(self, name, new):
         if not os.path.isdir(new):
             os.makedirs(new, mode = 0777)
         if not os.path.isdir(self.ipython_extension_dir):
             os.makedirs(self.ipython_extension_dir, mode = 0777)
 
     @property
     def ipython_extension_dir(self):
         return os.path.join(self.ipythondir, 'extensions')
 
     @property
     def usable_screen_length(self):
         if self.screen_length == 0:
             return 0
         else:
             num_lines_bot = self.separate_in.count('\n')+1
             return self.screen_length - num_lines_bot
 
     def _term_title_changed(self, name, new_value):
         self.init_term_title()
 
     def set_autoindent(self,value=None):
         """Set the autoindent flag, checking for readline support.
 
         If called with no arguments, it acts as a toggle."""
 
         if not self.has_readline:
             if os.name == 'posix':
                 warn("The auto-indent feature requires the readline library")
             self.autoindent = 0
             return
         if value is None:
             self.autoindent = not self.autoindent
         else:
             self.autoindent = value
 
     #-------------------------------------------------------------------------
     # init_* methods called by __init__
     #-------------------------------------------------------------------------
 
     def init_ipythondir(self, ipythondir):
         if ipythondir is not None:
             self.ipythondir = ipythondir
             self.config.Global.ipythondir = self.ipythondir
             return
 
         if hasattr(self.config.Global, 'ipythondir'):
             self.ipythondir = self.config.Global.ipythondir
         else:
             self.ipythondir = get_ipython_dir()
 
         # All children can just read this
         self.config.Global.ipythondir = self.ipythondir
 
     def init_instance_attrs(self):
         self.jobs = BackgroundJobManager()
         self.more = False
 
         # command compiler
         self.compile = codeop.CommandCompiler()
 
         # User input buffer
         self.buffer = []
 
         # 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()
 
         # Object variable to store code object waiting execution.  This is
         # used mainly by the multithreaded shells, but it can come in handy in
         # other situations.  No need to use a Queue here, since it's a single
         # item which gets cleared once run.
         self.code_to_run = None
 
         # Flag to mark unconditional exit
         self.exit_now = False
 
         # Temporary files used for various purposes.  Deleted at exit.
         self.tempfiles = []
 
         # Keep track of readline usage (later set by init_readline)
         self.has_readline = False
 
         # keep track of where we started running (mainly for crash post-mortem)
         # This is not being used anywhere currently.
         self.starting_dir = os.getcwd()
 
         # Indentation management
         self.indent_current_nsp = 0
 
     def init_term_title(self):
         # Enable or disable the terminal title.
         if self.term_title:
             toggle_set_term_title(True)
             set_term_title('IPython: ' + abbrev_cwd())
         else:
             toggle_set_term_title(False)
 
     def init_usage(self, usage=None):
         if usage is None:
             self.usage = interactive_usage
         else:
             self.usage = usage
 
     def init_encoding(self):
         # Get system encoding at startup time.  Certain terminals (like Emacs
         # under Win32 have it set to None, and we need to have a known valid
         # encoding to use in the raw_input() method
         try:
             self.stdin_encoding = sys.stdin.encoding or 'ascii'
         except AttributeError:
             self.stdin_encoding = 'ascii'
 
     def init_syntax_highlighting(self):
         # Python source parser/formatter for syntax highlighting
         pyformat = PyColorize.Parser().format
         self.pycolorize = lambda src: pyformat(src,'str',self.colors)
 
     def init_pushd_popd_magic(self):
         # for pushd/popd management
         try:
             self.home_dir = get_home_dir()
         except HomeDirError, msg:
             fatal(msg)
 
         self.dir_stack = []
 
     def init_logger(self):
         self.logger = Logger(self, logfname='ipython_log.py', logmode='rotate')
         # local shortcut, this is used a LOT
         self.log = self.logger.log
 
     def init_logstart(self):
         if self.logappend:
             self.magic_logstart(self.logappend + ' append')
         elif self.logfile:
             self.magic_logstart(self.logfile)
         elif self.logstart:
             self.magic_logstart()
 
     def init_builtins(self):
         self.builtin_trap = BuiltinTrap(self)
 
     def init_inspector(self):
         # Object inspector
         self.inspector = oinspect.Inspector(oinspect.InspectColors,
                                             PyColorize.ANSICodeColors,
                                             'NoColor',
                                             self.object_info_string_level)
 
     def init_prompts(self):
         # Initialize cache, set in/out prompts and printing system
         self.outputcache = CachedOutput(self,
                                         self.cache_size,
                                         self.pprint,
                                         input_sep = self.separate_in,
                                         output_sep = self.separate_out,
                                         output_sep2 = self.separate_out2,
                                         ps1 = self.prompt_in1,
                                         ps2 = self.prompt_in2,
                                         ps_out = self.prompt_out,
                                         pad_left = self.prompts_pad_left)
 
         # user may have over-ridden the default print hook:
         try:
             self.outputcache.__class__.display = self.hooks.display
         except AttributeError:
             pass
 
     def init_displayhook(self):
         self.display_trap = DisplayTrap(self, self.outputcache)
 
     def init_reload_doctest(self):
         # Do a proper resetting of doctest, including the necessary displayhook
         # monkeypatching
         try:
             doctest_reload()
         except ImportError:
             warn("doctest module does not exist.")
 
     #-------------------------------------------------------------------------
     # Things related to the banner
     #-------------------------------------------------------------------------
 
     def init_banner(self, banner1, banner2, display_banner):
         if banner1 is not None:
             self.banner1 = banner1
         if banner2 is not None:
             self.banner2 = banner2
         if display_banner is not None:
             self.display_banner = display_banner
         self.compute_banner()
 
     def show_banner(self, banner=None):
         if banner is None:
             banner = self.banner
         self.write(banner)
 
     def compute_banner(self):
         self.banner = self.banner1 + '\n'
         if self.profile:
             self.banner += '\nIPython profile: %s\n' % self.profile
         if self.banner2:
             self.banner += '\n' + self.banner2 + '\n'
 
     #-------------------------------------------------------------------------
     # 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_ns is created.
         """
         self._orig_sys_module_state = {}
         self._orig_sys_module_state['stdin'] = sys.stdin
         self._orig_sys_module_state['stdout'] = sys.stdout
         self._orig_sys_module_state['stderr'] = sys.stderr
         self._orig_sys_module_state['excepthook'] = sys.excepthook
         try:
             self._orig_sys_modules_main_name = self.user_ns['__name__']
         except KeyError:
             pass
 
     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
         try:
             delattr(sys, 'ipcompleter')
         except AttributeError:
             pass
         # Reset what what done in self.init_sys_modules
         try:
             sys.modules[self.user_ns['__name__']] = self._orig_sys_modules_main_name
         except (AttributeError, KeyError):
             pass
 
     #-------------------------------------------------------------------------
     # 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.
         import IPython.core.hooks
         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)
 
     def set_hook(self,name,hook, priority = 50, str_key = None, re_key = None):
         """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 = new.instancemethod(hook,self,self.__class__)
 
         # 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 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 the "main" module
     #-------------------------------------------------------------------------
 
     def new_main_mod(self,ns=None):
         """Return a new 'main' module object for user code execution.
         """
         main_mod = self._user_main_module
         init_fakemod_dict(main_mod,ns)
         return main_mod
 
     def cache_main_mod(self,ns,fname):
         """Cache a main module's namespace.
 
         When scripts are executed via %run, we must keep a reference to the
         namespace of their __main__ module (a FakeModule instance) around so
         that Python doesn't clear it, rendering objects defined therein
         useless.
 
         This method keeps said reference in a private dict, keyed by the
         absolute path of the module object (which corresponds to the script
         path).  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.
 
         Note: we can not allow the actual FakeModule instances to be deleted,
         because of how Python tears down modules (it hard-sets all their
         references to None without regard for reference counts).  This method
         must therefore make a *copy* of the given namespace, to allow the
         original module's __dict__ to be cleared and reused.
 
         
         Parameters
         ----------
           ns : a namespace (a dict, typically)
 
           fname : str
             Filename associated with the namespace.
 
         Examples
         --------
 
         In [10]: import IPython
 
         In [11]: _ip.cache_main_mod(IPython.__dict__,IPython.__file__)
 
         In [12]: IPython.__file__ in _ip._main_ns_cache
         Out[12]: True
         """
         self._main_ns_cache[os.path.abspath(fname)] = ns.copy()
 
     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]: _ip.cache_main_mod(IPython.__dict__,IPython.__file__)
 
         In [17]: len(_ip._main_ns_cache) > 0
         Out[17]: True
 
         In [18]: _ip.clear_main_mod_cache()
 
         In [19]: len(_ip._main_ns_cache) == 0
         Out[19]: True
         """
         self._main_ns_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
         if self.isthreaded:
             try:
                 self.sys_excepthook.call_pdb = val
             except:
                 warn('Failed to activate pdb for threaded exception handler')
 
     call_pdb = property(_get_call_pdb,_set_call_pdb,None,
                         'Control auto-activation of pdb at exceptions')
 
     def debugger(self,force=False):
         """Call the pydb/pdb debugger.
 
         Keywords:
 
           - force(False): by default, this routine checks the instance call_pdb
           flag and does not actually invoke the debugger if the flag is false.
           The 'force' option forces the debugger to activate even if the flag
           is false.
         """
 
         if not (force or self.call_pdb):
             return
 
         if not hasattr(sys,'last_traceback'):
             error('No traceback has been produced, nothing to debug.')
             return
 
         # use pydb if available
         if debugger.has_pydb:
             from pydb import pm
         else:
             # fallback to our internal debugger
             pm = lambda : self.InteractiveTB.debugger(force=True)
         self.history_saving_wrapper(pm)()
 
     #-------------------------------------------------------------------------
     # Things related to IPython's various namespaces
     #-------------------------------------------------------------------------
 
     def init_create_namespaces(self, user_ns=None, user_global_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 properly built dicts as needed by the rest of
         # the code, and can also be used by extension writers to generate
         # properly initialized namespaces.
         user_ns, user_global_ns = self.make_user_namespaces(user_ns,
             user_global_ns)
 
         # Assign namespaces
         # This is the namespace where all normal user variables live
         self.user_ns = user_ns
         self.user_global_ns = user_global_ns
 
         # An auxiliary namespace that checks what parts of the user_ns were
         # loaded at startup, so we can list later only variables defined in
         # actual interactive use.  Since it is always a subset of user_ns, it
         # doesn't need to be seaparately tracked in the ns_table
         self.user_config_ns = {}
 
         # A namespace to keep track of internal data structures to prevent
         # them from cluttering user-visible stuff.  Will be updated later
         self.internal_ns = {}
 
         # Now that FakeModule produces a real module, we've run into a nasty
         # problem: after script execution (via %run), the module where the user
         # code ran is deleted.  Now that this object is a true module (needed
         # so docetst and other tools work correctly), the Python module
         # teardown mechanism runs over it, and sets to None every variable
         # present in that module.  Top-level references to objects from the
         # script survive, because the user_ns is updated with them.  However,
         # calling functions defined in the script that use other things from
         # the script will fail, because the function's closure had references
         # to the original objects, which are now all None.  So we must protect
         # these modules from deletion by keeping a cache.
         # 
         # To avoid keeping stale modules around (we only need the one from the
         # last run), we use a dict keyed with the full path to the script, so
         # only the last version of the module is held in the cache.  Note,
         # however, that we must cache the module *namespace contents* (their
         # __dict__).  Because if we try to cache the actual modules, old ones
         # (uncached) could be destroyed while still holding references (such as
         # those held by GUI objects that tend to be long-lived)>
         # 
         # The %reset command will flush this cache.  See the cache_main_mod()
         # and clear_main_mod_cache() methods for details on use.
 
         # This is the cache used for 'main' namespaces
         self._main_ns_cache = {}
         # And this is the single instance of FakeModule whose __dict__ we keep
         # copying and clearing for reuse on each %run
         self._user_main_module = FakeModule()
 
         # A table holding all the namespaces IPython deals with, so that
         # introspection facilities can search easily.
         self.ns_table = {'user':user_ns,
                          'user_global':user_global_ns,
                          'internal':self.internal_ns,
                          'builtin':__builtin__.__dict__
                          }
 
         # Similarly, track all namespaces where references can be held and that
         # we can safely clear (so it can NOT include builtin).  This one can be
         # a simple list.
         self.ns_refs_table = [ user_ns, user_global_ns, self.user_config_ns,
                                self.internal_ns, self._main_ns_cache ]
 
     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.
 
         try:
             main_name = self.user_ns['__name__']
         except KeyError:
             raise KeyError('user_ns dictionary MUST have a "__name__" key')
         else:
             sys.modules[main_name] = FakeModule(self.user_ns)
 
     def make_user_namespaces(self, user_ns=None, user_global_ns=None):
         """Return a valid local and global user interactive namespaces.
 
         This builds a dict with the minimal information needed to operate as a
         valid IPython user namespace, which you can pass to the various
         embedding classes in ipython. The default implementation returns the
         same dict for both the locals and the globals to allow functions to
         refer to variables in the namespace. Customized implementations can
         return different dicts. The locals dictionary can actually be anything
         following the basic mapping protocol of a dict, but the globals dict
         must be a true dict, not even a subclass. It is recommended that any
         custom object for the locals namespace synchronize with the globals
         dict somehow.
 
         Raises TypeError if the provided globals namespace is not a true dict.
 
         :Parameters:
             user_ns : dict-like, optional
                 The current user namespace. The items in this namespace should
                 be included in the output. If None, an appropriate blank
                 namespace should be created.
             user_global_ns : dict, optional
                 The current user global namespace. The items in this namespace
                 should be included in the output. If None, an appropriate
                 blank namespace should be created.
 
         :Returns:
             A tuple pair of dictionary-like object to be used as the local namespace
             of the interpreter and a dict to be used as the global namespace.
         """
 
         if user_ns is None:
             # Set __name__ to __main__ to better match the behavior of the
             # normal interpreter.
             user_ns = {'__name__'     :'__main__',
                        '__builtins__' : __builtin__,
                       }
         else:
             user_ns.setdefault('__name__','__main__')
             user_ns.setdefault('__builtins__',__builtin__)
 
         if user_global_ns is None:
             user_global_ns = user_ns
         if type(user_global_ns) is not dict:
             raise TypeError("user_global_ns must be a true dict; got %r"
                 % type(user_global_ns))
 
         return user_ns, user_global_ns
 
     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.
         """
         # Store myself as the public api!!!
         self.user_ns['get_ipython'] = self.get_ipython
 
         # make global variables for user access to the histories
         self.user_ns['_ih'] = self.input_hist
         self.user_ns['_oh'] = self.output_hist
         self.user_ns['_dh'] = self.dir_hist
 
         # user aliases to input and output histories
         self.user_ns['In']  = self.input_hist
         self.user_ns['Out'] = self.output_hist
 
         self.user_ns['_sh'] = shadowns
 
         # Put 'help' in the user namespace
         try:
             from site import _Helper
             self.user_ns['help'] = _Helper()
         except ImportError:
             warn('help() not available - check site.py')
 
     def reset(self):
         """Clear all internal namespaces.
 
         Note that this is much more aggressive than %reset, since it clears
         fully all namespaces, as well as all input/output lists.
         """
         for ns in self.ns_refs_table:
             ns.clear()
 
         self.alias_manager.clear_aliases()
 
         # Clear input and output histories
         self.input_hist[:] = []
         self.input_hist_raw[:] = []
         self.output_hist.clear()
 
         # Restore the user namespaces to minimal usability
         self.init_user_ns()
 
         # Restore the default and user aliases
         self.alias_manager.init_aliases()
 
     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, (basestring, list, tuple)):
             if isinstance(variables, basestring):
                 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
         config_ns = self.user_config_ns
         if interactive:
             for name, val in vdict.iteritems():
                 config_ns.pop(name, None)
         else:
             for name,val in vdict.iteritems():
                 config_ns[name] = val
 
     #-------------------------------------------------------------------------
     # Things related to history management
     #-------------------------------------------------------------------------
 
     def init_history(self):
         # List of input with multi-line handling.
         self.input_hist = InputList()
         # This one will hold the 'raw' input history, without any
         # pre-processing.  This will allow users to retrieve the input just as
         # it was exactly typed in by the user, with %hist -r.
         self.input_hist_raw = InputList()
 
         # list of visited directories
         try:
             self.dir_hist = [os.getcwd()]
         except OSError:
             self.dir_hist = []
 
         # dict of output history
         self.output_hist = {}
 
         # Now the history file
         if self.profile:
             histfname = 'history-%s' % self.profile
         else:
             histfname = 'history'
         self.histfile = os.path.join(self.ipythondir, histfname)
 
         # Fill the history zero entry, user counter starts at 1
         self.input_hist.append('\n')
         self.input_hist_raw.append('\n')
 
     def init_shadow_hist(self):
         try:
             self.db = pickleshare.PickleShareDB(self.ipythondir + "/db")
         except exceptions.UnicodeDecodeError:
             print "Your ipythondir can't be decoded to unicode!"
             print "Please set HOME environment variable to something that"
             print r"only has ASCII characters, e.g. c:\home"
             print "Now it is", self.ipythondir
             sys.exit()
         self.shadowhist = ipcorehist.ShadowHist(self.db)
 
     def savehist(self):
         """Save input history to a file (via readline library)."""
 
         if not self.has_readline:
             return
         
         try:
             self.readline.write_history_file(self.histfile)
         except:
             print 'Unable to save IPython command history to file: ' + \
                   `self.histfile`
 
     def reloadhist(self):
         """Reload the input history from disk file."""
 
         if self.has_readline:
             try:
                 self.readline.clear_history()
                 self.readline.read_history_file(self.shell.histfile)
             except AttributeError:
                 pass
 
     def history_saving_wrapper(self, func):
         """ Wrap func for readline history saving
 
         Convert func into callable that saves & restores
         history around the call """
 
         if not self.has_readline:
             return func
 
         def wrapper():
             self.savehist()
             try:
                 func()
             finally:
                 readline.read_history_file(self.histfile)
         return wrapper
 
     #-------------------------------------------------------------------------
     # Things related to exception handling and tracebacks (not debugging)
     #-------------------------------------------------------------------------
 
     def init_traceback_handlers(self, custom_exceptions):
         # Syntax error handler.
         self.SyntaxTB = SyntaxTB(color_scheme='NoColor')
         
         # The interactive one is initialized with an offset, meaning we always
         # want to remove the topmost item in the traceback, which is our own
         # internal code. Valid modes: ['Plain','Context','Verbose']
         self.InteractiveTB = ultratb.AutoFormattedTB(mode = 'Plain',
                                                      color_scheme='NoColor',
                                                      tb_offset = 1)
 
         # IPython itself shouldn't crash. This will produce a detailed
         # post-mortem if it does.  But we only install the crash handler for
         # non-threaded shells, the threaded ones use a normal verbose reporter
         # and lose the crash handler.  This is because exceptions in the main
         # thread (such as in GUI code) propagate directly to sys.excepthook,
         # and there's no point in printing crash dumps for every user exception.
         if self.isthreaded:
             ipCrashHandler = ultratb.FormattedTB()
         else:
             from IPython.core import crashhandler
             ipCrashHandler = crashhandler.IPythonCrashHandler(self)
         self.set_crash_handler(ipCrashHandler)
 
         # and add any custom exception handlers the user may have specified
         self.set_custom_exc(*custom_exceptions)
 
     def set_crash_handler(self, crashHandler):
         """Set the IPython crash handler.
 
         This must be a callable with a signature suitable for use as
         sys.excepthook."""
 
         # Install the given crash handler as the Python exception hook
         sys.excepthook = crashHandler
         
         # The instance will store a pointer to this, so that runtime code
         # (such as magics) can access it.  This is because during the
         # read-eval loop, it gets temporarily overwritten (to deal with GUI
         # frameworks).
         self.sys_excepthook = sys.excepthook
 
     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
         runcode() method.
 
         Inputs:
 
           - exc_tuple: a *tuple* of valid exceptions to call the defined
           handler for.  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: this must be defined as a function with the following
           basic interface: def my_handler(self,etype,value,tb).
 
           This will be made into an instance method (via new.instancemethod)
           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.
 
         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):
             print '*** Simple custom exception handler ***'
             print 'Exception type :',etype
             print 'Exception value:',value
             print 'Traceback      :',tb
             print 'Source code    :','\n'.join(self.buffer)
 
         if handler is None: handler = dummy_handler
 
         self.CustomTB = new.instancemethod(handler,self,self.__class__)
         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 showtraceback(self,exc_tuple = None,filename=None,tb_offset=None):
         """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."""
 
         
         # Though this won't be called by syntax errors in the input line,
         # there may be SyntaxError cases whith imported code.
         
         try:
             if exc_tuple is None:
                 etype, value, tb = sys.exc_info()
             else:
                 etype, value, tb = exc_tuple
     
             if etype is SyntaxError:
                 self.showsyntaxerror(filename)
             elif etype is UsageError:
                 print "UsageError:", value
             else:
                 # 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
     
                 if etype in self.custom_exceptions:
                     self.CustomTB(etype,value,tb)
                 else:
                     self.InteractiveTB(etype,value,tb,tb_offset=tb_offset)
                     if self.InteractiveTB.call_pdb and self.has_readline:
                         # pdb mucks up readline, fix it back
                         self.set_completer()
         except KeyboardInterrupt:
             self.write("\nKeyboardInterrupt\n")
 
     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 = sys.exc_info()
 
         # See note about these variables in showtraceback() below
         sys.last_type = etype
         sys.last_value = value
         sys.last_traceback = last_traceback
         
         if filename and etype is SyntaxError:
             # Work hard to stuff the correct filename in the exception
             try:
                 msg, (dummy_filename, lineno, offset, line) = value
             except:
                 # Not the format we expect; leave it alone
                 pass
             else:
                 # Stuff in the right filename
                 try:
                     # Assume SyntaxError is a class exception
                     value = SyntaxError(msg, (filename, lineno, offset, line))
                 except:
                     # If that failed, assume SyntaxError is a string
                     value = msg, (filename, lineno, offset, line)
         self.SyntaxTB(etype,value,[])
 
     def edit_syntax_error(self):
         """The bottom half of the syntax error handler called in the main loop.
 
         Loop until syntax error is fixed or user cancels.
         """
 
         while self.SyntaxTB.last_syntax_error:
             # copy and clear last_syntax_error
             err = self.SyntaxTB.clear_err_state()
             if not self._should_recompile(err):
                 return
             try:
                 # may set last_syntax_error again if a SyntaxError is raised
                 self.safe_execfile(err.filename,self.user_ns)
             except:
                 self.showtraceback()
             else:
                 try:
                     f = file(err.filename)
                     try:
                         # This should be inside a display_trap block and I 
                         # think it is.
                         sys.displayhook(f.read())
                     finally:
                         f.close()
                 except:
                     self.showtraceback()
 
     def _should_recompile(self,e):
         """Utility routine for edit_syntax_error"""
 
         if e.filename in ('<ipython console>','<input>','<string>',
                           '<console>','<BackgroundJob compilation>',
                           None):
                               
             return False
         try:
             if (self.autoedit_syntax and 
                 not self.ask_yes_no('Return to editor to correct syntax error? '
                               '[Y/n] ','y')):
                 return False
         except EOFError:
             return False
 
         def int0(x):
             try:
                 return int(x)
             except TypeError:
                 return 0
         # always pass integer line and offset values to editor hook
         try:
             self.hooks.fix_error_editor(e.filename,
                 int0(e.lineno),int0(e.offset),e.msg)
         except TryNext:
             warn('Could not open editor')
             return False
         return True
 
     #-------------------------------------------------------------------------
     # Things related to tab completion
     #-------------------------------------------------------------------------
 
     def complete(self, text):
         """Return a sorted list of all possible completions on text.
 
         Inputs:
 
           - text: a string of text to be completed on.
 
         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 [7]: x = 'hello'
 
         In [8]: x
         Out[8]: 'hello'
 
         In [9]: print x
         hello
 
         In [10]: _ip.complete('x.l')
         Out[10]: ['x.ljust', 'x.lower', 'x.lstrip']
         """
 
         # Inject names into __builtin__ so we can complete on the added names.
         with self.builtin_trap:
             complete = self.Completer.complete
             state = 0
             # use a dict so we get unique keys, since ipyhton's multiple
             # completers can return duplicates.  When we make 2.4 a requirement,
             # start using sets instead, which are faster.
             comps = {}
             while True:
                 newcomp = complete(text,state,line_buffer=text)
                 if newcomp is None:
                     break
                 comps[newcomp] = 1
                 state += 1
             outcomps = comps.keys()
             outcomps.sort()
             #print "T:",text,"OC:",outcomps  # dbg
             #print "vars:",self.user_ns.keys()
             return outcomps
 
     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 = new.instancemethod(completer,self.Completer,
                                      self.Completer.__class__)
         self.Completer.matchers.insert(pos,newcomp)
 
     def set_completer(self):
         """Reset readline's completer to be our own."""
         self.readline.set_completer(self.Completer.complete)
 
     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 readline
     #-------------------------------------------------------------------------
 
     def init_readline(self):
         """Command history completion/saving/reloading."""
 
         self.rl_next_input = None
         self.rl_do_indent = False
 
         if not self.readline_use:
             return
 
         import IPython.utils.rlineimpl as readline
                   
         if not readline.have_readline:
             self.has_readline = 0
             self.readline = None
             # no point in bugging windows users with this every time:
             warn('Readline services not available on this platform.')
         else:
             sys.modules['readline'] = readline
             import atexit
             from IPython.core.completer import IPCompleter
             self.Completer = IPCompleter(self,
                                          self.user_ns,
                                          self.user_global_ns,
                                          self.readline_omit__names,
                                          self.alias_manager.alias_table)
             sdisp = self.strdispatchers.get('complete_command', StrDispatch())
             self.strdispatchers['complete_command'] = sdisp
             self.Completer.custom_completers = sdisp
             # Platform-specific configuration
             if os.name == 'nt':
                 self.readline_startup_hook = readline.set_pre_input_hook
             else:
                 self.readline_startup_hook = readline.set_startup_hook
 
             # Load user's initrc file (readline config)
             # Or if libedit is used, load editrc.
             inputrc_name = os.environ.get('INPUTRC')
             if inputrc_name is None:
                 home_dir = get_home_dir()
                 if home_dir is not None:
                     inputrc_name = '.inputrc'
                     if readline.uses_libedit:
                         inputrc_name = '.editrc'
                     inputrc_name = os.path.join(home_dir, inputrc_name)
             if os.path.isfile(inputrc_name):
                 try:
                     readline.read_init_file(inputrc_name)
                 except:
                     warn('Problems reading readline initialization file <%s>'
                          % inputrc_name)
             
             self.has_readline = 1
             self.readline = readline
             # save this in sys so embedded copies can restore it properly
             sys.ipcompleter = self.Completer.complete
             self.set_completer()
 
             # Configure readline according to user's prefs
             # This is only done if GNU readline is being used.  If libedit
             # is being used (as on Leopard) the readline config is
             # not run as the syntax for libedit is different.
             if not readline.uses_libedit:
                 for rlcommand in self.readline_parse_and_bind:
                     #print "loading rl:",rlcommand  # dbg
                     readline.parse_and_bind(rlcommand)
 
             # Remove some chars from the delimiters list.  If we encounter
             # unicode chars, discard them.
             delims = readline.get_completer_delims().encode("ascii", "ignore")
             delims = delims.translate(string._idmap,
                                       self.readline_remove_delims)
             readline.set_completer_delims(delims)
             # otherwise we end up with a monster history after a while:
             readline.set_history_length(1000)
             try:
                 #print '*** Reading readline history'  # dbg
                 readline.read_history_file(self.histfile)
             except IOError:
                 pass  # It doesn't exist yet.
 
             atexit.register(self.atexit_operations)
             del atexit
 
         # Configure auto-indent for all platforms
         self.set_autoindent(self.autoindent)
 
     def set_next_input(self, s):
         """ Sets the 'default' input string for the next command line.
         
         Requires readline.
         
         Example:
         
         [D:\ipython]|1> _ip.set_next_input("Hello Word")
         [D:\ipython]|2> Hello Word_  # cursor is here        
         """
 
         self.rl_next_input = s
 
     def pre_readline(self):
         """readline hook to be used at the start of each line.
 
         Currently it handles auto-indent only."""
 
         #debugx('self.indent_current_nsp','pre_readline:')
 
         if self.rl_do_indent:
             self.readline.insert_text(self._indent_current_str())
         if self.rl_next_input is not None:
             self.readline.insert_text(self.rl_next_input)
             self.rl_next_input = None
 
     def _indent_current_str(self):
         """return the current level of indentation as a string"""
         return self.indent_current_nsp * ' '
 
     #-------------------------------------------------------------------------
     # Things related to magics
     #-------------------------------------------------------------------------
 
     def init_magics(self):
         # Set user colors (don't do it in the constructor above so that it
         # doesn't crash if colors option is invalid)
         self.magic_colors(self.colors)
 
     def magic(self,arg_s):
         """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.
         """
 
         args = arg_s.split(' ',1)
         magic_name = args[0]
         magic_name = magic_name.lstrip(prefilter.ESC_MAGIC)
 
         try:
             magic_args = args[1]
         except IndexError:
             magic_args = ''
         fn = getattr(self,'magic_'+magic_name,None)
         if fn is None:
             error("Magic function `%s` not found." % magic_name)
         else:
             magic_args = self.var_expand(magic_args,1)
             with nested(self.builtin_trap,):
                 result = fn(magic_args)
                 return result
 
     def define_magic(self, magicname, func):
         """Expose own function as magic function for ipython 
     
         def foo_impl(self,parameter_s=''):
             'My very own magic!. (Use docstrings, IPython reads them).'
             print 'Magic function. Passed parameter is between < >:'
             print '<%s>' % parameter_s
             print 'The self object is:',self
     
         self.define_magic('foo',foo_impl)
         """
         
         import new
         im = new.instancemethod(func,self, self.__class__)
         old = getattr(self, "magic_" + magicname, None)
         setattr(self, "magic_" + magicname, im)
         return old
 
     #-------------------------------------------------------------------------
     # 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, basestring):
             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(self, cmd):
         """Make a system call, using IPython."""
         return self.hooks.shell_hook(self.var_expand(cmd, depth=2))
 
     #-------------------------------------------------------------------------
     # Things related to aliases
     #-------------------------------------------------------------------------
 
     def init_alias(self):
         self.alias_manager = AliasManager(self, config=self.config)
         self.ns_table['alias'] = self.alias_manager.alias_table,
 
     #-------------------------------------------------------------------------
     # Things related to the running of code
     #-------------------------------------------------------------------------
 
     def ex(self, cmd):
         """Execute a normal python statement in user namespace."""
         with nested(self.builtin_trap,):
             exec cmd in self.user_global_ns, self.user_ns
 
     def ev(self, expr):
         """Evaluate python expression expr in user namespace.
 
         Returns the result of evaluation
         """
         with nested(self.builtin_trap,):
             return eval(expr, self.user_global_ns, self.user_ns)
 
     def mainloop(self, display_banner=None):
         """Start the mainloop.
 
         If an optional banner argument is given, it will override the
         internally created default banner.
         """
         
         with nested(self.builtin_trap, self.display_trap):
 
             # if you run stuff with -c <cmd>, raw hist is not updated
             # ensure that it's in sync
             if len(self.input_hist) != len (self.input_hist_raw):
                 self.input_hist_raw = InputList(self.input_hist)
 
             while 1:
                 try:
                     self.interact(display_banner=display_banner)
                     #self.interact_with_readline()                
                     # XXX for testing of a readline-decoupled repl loop, call
                     # interact_with_readline above
                     break
                 except KeyboardInterrupt:
                     # this should not be necessary, but KeyboardInterrupt
                     # handling seems rather unpredictable...
                     self.write("\nKeyboardInterrupt in interact()\n")
 
     def interact_prompt(self):
         """ Print the prompt (in read-eval-print loop) 
 
         Provided for those who want to implement their own read-eval-print loop (e.g. GUIs), not 
         used in standard IPython flow.
         """
         if self.more:
             try:
                 prompt = self.hooks.generate_prompt(True)
             except:
                 self.showtraceback()
             if self.autoindent:
                 self.rl_do_indent = True
 
         else:
             try:
                 prompt = self.hooks.generate_prompt(False)
             except:
                 self.showtraceback()
         self.write(prompt)
 
     def interact_handle_input(self,line):
         """ Handle the input line (in read-eval-print loop)
         
         Provided for those who want to implement their own read-eval-print loop (e.g. GUIs), not 
         used in standard IPython flow.        
         """
         if line.lstrip() == line:
             self.shadowhist.add(line.strip())
         lineout = self.prefilter_manager.prefilter_lines(line,self.more)
 
         if line.strip():
             if self.more:
                 self.input_hist_raw[-1] += '%s\n' % line
             else:
                 self.input_hist_raw.append('%s\n' % line)                
 
         
         self.more = self.push_line(lineout)
         if (self.SyntaxTB.last_syntax_error and
             self.autoedit_syntax):
             self.edit_syntax_error()
 
     def interact_with_readline(self):
         """ Demo of using interact_handle_input, interact_prompt
         
         This is the main read-eval-print loop. If you need to implement your own (e.g. for GUI),
         it should work like this.
         """ 
         self.readline_startup_hook(self.pre_readline)
         while not self.exit_now:
             self.interact_prompt()
             if self.more:
                 self.rl_do_indent = True
             else:
                 self.rl_do_indent = False
             line = raw_input_original().decode(self.stdin_encoding)
             self.interact_handle_input(line)
 
     def interact(self, display_banner=None):
         """Closely emulate the interactive Python console."""
 
         # batch run -> do not interact        
         if self.exit_now:
             return
 
         if display_banner is None:
             display_banner = self.display_banner
         if display_banner:
             self.show_banner()
 
         more = 0
         
         # Mark activity in the builtins
         __builtin__.__dict__['__IPYTHON__active'] += 1
         
         if self.has_readline:
             self.readline_startup_hook(self.pre_readline)
         # exit_now is set by a call to %Exit or %Quit, through the
         # ask_exit callback.
         
         while not self.exit_now:
             self.hooks.pre_prompt_hook()
             if more:
                 try:
                     prompt = self.hooks.generate_prompt(True)
                 except:
                     self.showtraceback()
                 if self.autoindent:
                     self.rl_do_indent = True
                     
             else:
                 try:
                     prompt = self.hooks.generate_prompt(False)
                 except:
                     self.showtraceback()
             try:
                 line = self.raw_input(prompt, more)
                 if self.exit_now:
                     # quick exit on sys.std[in|out] close
                     break
                 if self.autoindent:
                     self.rl_do_indent = False
                     
             except KeyboardInterrupt:
                 #double-guard against keyboardinterrupts during kbdint handling
                 try:
                     self.write('\nKeyboardInterrupt\n')
                     self.resetbuffer()
                     # keep cache in sync with the prompt counter:
                     self.outputcache.prompt_count -= 1
     
                     if self.autoindent:
                         self.indent_current_nsp = 0
                     more = 0
                 except KeyboardInterrupt:
                     pass
             except EOFError:
                 if self.autoindent:
                     self.rl_do_indent = False
                     self.readline_startup_hook(None)
                 self.write('\n')
                 self.exit()
             except bdb.BdbQuit:
                 warn('The Python debugger has exited with a BdbQuit exception.\n'
                      'Because of how pdb handles the stack, it is impossible\n'
                      'for IPython to properly format this particular exception.\n'
                      'IPython will resume normal operation.')
             except:
                 # exceptions here are VERY RARE, but they can be triggered
                 # asynchronously by signal handlers, for example.
                 self.showtraceback()
             else:
                 more = self.push_line(line)
                 if (self.SyntaxTB.last_syntax_error and
                     self.autoedit_syntax):
                     self.edit_syntax_error()
             
         # We are off again...
         __builtin__.__dict__['__IPYTHON__active'] -= 1
 
     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 don't print errors for non-zero exit statuses.
         """
         kw.setdefault('exit_ignore', False)
 
         fname = os.path.abspath(os.path.expanduser(fname))
 
         # Make sure we have a .py file
         if not fname.endswith('.py'):
             warn('File must end with .py to be run using execfile: <%s>' % fname)
 
         # Make sure we can open the file
         try:
             with open(fname) as thefile:
                 pass
         except:
             warn('Could not open file <%s> for safe execution.' % fname)
             return
 
         # Find things also in current directory.  This is needed to mimic the
         # behavior of running a script from the system command line, where
         # Python inserts the script's directory into sys.path
         dname = os.path.dirname(fname)
 
         with prepended_to_syspath(dname):
             try:
                 if sys.platform == 'win32' and sys.version_info < (2,5,1):
                     # Work around a bug in Python for Windows.  The bug was
                     # fixed in in Python 2.5 r54159 and 54158, but that's still
                     # SVN Python as of March/07.  For details, see:
                     # http://projects.scipy.org/ipython/ipython/ticket/123
                     try:
                         globs,locs = where[0:2]
                     except:
                         try:
                             globs = locs = where[0]
                         except:
                             globs = locs = globals()
                     exec file(fname) in globs,locs
                 else:
                     execfile(fname,*where)
             except SyntaxError:
                 self.showsyntaxerror()
                 warn('Failure executing file: <%s>' % fname)
             except SystemExit, status:
                 # Code that correctly sets the exit status flag to success (0)
                 # shouldn't be bothered with a traceback.  Note that a plain
                 # sys.exit() does NOT set the message to 0 (it's empty) so that
                 # will still get a traceback.  Note that the structure of the
                 # SystemExit exception changed between Python 2.4 and 2.5, so
                 # the checks must be done in a version-dependent way.
                 show = False
                 if status.args[0]==0 and not kw['exit_ignore']:
                     show = True
                 if show:
                     self.showtraceback()
                     warn('Failure executing file: <%s>' % fname)
             except:
                 self.showtraceback()
                 warn('Failure executing file: <%s>' % fname)
 
     def safe_execfile_ipy(self, fname):
         """Like safe_execfile, but for .ipy files with IPython syntax.
 
         Parameters
         ----------
         fname : str
             The name of the file to execute.  The filename must have a
             .ipy extension.
         """
         fname = os.path.abspath(os.path.expanduser(fname))
 
         # Make sure we have a .py file
         if not fname.endswith('.ipy'):
             warn('File must end with .py to be run using execfile: <%s>' % fname)
 
         # Make sure we can open the file
         try:
             with open(fname) as thefile:
                 pass
         except:
             warn('Could not open file <%s> for safe execution.' % fname)
             return
 
         # Find things also in current directory.  This is needed to mimic the
         # behavior of running a script from the system command line, where
         # Python inserts the script's directory into sys.path
         dname = os.path.dirname(fname)
 
         with prepended_to_syspath(dname):
             try:
                 with open(fname) as thefile:
                     script = thefile.read()
                     # self.runlines currently captures all exceptions
                     # raise in user code.  It would be nice if there were
                     # versions of runlines, execfile that did raise, so
                     # we could catch the errors.
                     self.runlines(script, clean=True)
             except:
                 self.showtraceback()
                 warn('Unknown failure executing file: <%s>' % fname)
                 
     def _is_secondary_block_start(self, s):
         if not s.endswith(':'):
             return False
         if (s.startswith('elif') or 
             s.startswith('else') or 
             s.startswith('except') or
             s.startswith('finally')):
             return True
 
     def cleanup_ipy_script(self, script):
         """Make a script safe for self.runlines()
 
         Currently, IPython is lines based, with blocks being detected by
         empty lines.  This is a problem for block based scripts that may
         not have empty lines after blocks.  This script adds those empty
         lines to make scripts safe for running in the current line based
         IPython.
         """
         res = []
         lines = script.splitlines()
         level = 0
 
         for l in lines:
             lstripped = l.lstrip()
             stripped = l.strip()                
             if not stripped:
                 continue
             newlevel = len(l) - len(lstripped)                    
             if level > 0 and newlevel == 0 and \
                    not self._is_secondary_block_start(stripped): 
                 # add empty line
                 res.append('')
             res.append(l)
             level = newlevel
 
         return '\n'.join(res) + '\n'
 
     def runlines(self, lines, clean=False):
         """Run a string of one or more lines of source.
 
         This method is capable of running a string containing multiple source
         lines, as if they had been entered at the IPython prompt.  Since it
         exposes IPython's processing machinery, the given strings can contain
         magic calls (%magic), special shell access (!cmd), etc.
         """
 
         if isinstance(lines, (list, tuple)):
             lines = '\n'.join(lines)
 
         if clean:
             lines = self.cleanup_ipy_script(lines)
 
         # We must start with a clean buffer, in case this is run from an
         # interactive IPython session (via a magic, for example).
         self.resetbuffer()
         lines = lines.splitlines()
         more = 0
 
         with nested(self.builtin_trap, self.display_trap):
             for line in lines:
                 # skip blank lines so we don't mess up the prompt counter, but do
                 # NOT skip even a blank line if we are in a code block (more is
                 # true)
             
                 if line or more:
                     # push to raw history, so hist line numbers stay in sync
                     self.input_hist_raw.append("# " + line + "\n")
                     prefiltered = self.prefilter_manager.prefilter_lines(line,more)
                     more = self.push_line(prefiltered)
                     # IPython's runsource returns None if there was an error
                     # compiling the code.  This allows us to stop processing right
                     # away, so the user gets the error message at the right place.
                     if more is None:
                         break
                 else:
                     self.input_hist_raw.append("\n")
             # final newline in case the input didn't have it, so that the code
             # actually does get executed
             if more:
                 self.push_line('\n')
 
     def runsource(self, source, filename='<input>', symbol='single'):
         """Compile and run some source in the interpreter.
 
         Arguments are as for compile_command().
 
         One several things can happen:
 
         1) The input is incorrect; compile_command() raised an
         exception (SyntaxError or OverflowError).  A syntax traceback
         will be printed by calling the showsyntaxerror() method.
 
         2) The input is incomplete, and more input is required;
         compile_command() returned None.  Nothing happens.
 
         3) The input is complete; compile_command() returned a code
         object.  The code is executed by calling self.runcode() (which
         also handles run-time exceptions, except for SystemExit).
 
         The return value is:
 
           - True in case 2
 
           - False in the other cases, unless an exception is raised, where
           None is returned instead.  This can be used by external callers to
           know whether to continue feeding input or not.
 
         The return value can be used to decide whether to use sys.ps1 or
         sys.ps2 to prompt the next line."""
 
         # if the source code has leading blanks, add 'if 1:\n' to it
         # this allows execution of indented pasted code. It is tempting
         # to add '\n' at the end of source to run commands like ' a=1'
         # directly, but this fails for more complicated scenarios
         source=source.encode(self.stdin_encoding)
         if source[:1] in [' ', '\t']:
             source = 'if 1:\n%s' % source
 
         try:
             code = self.compile(source,filename,symbol)
         except (OverflowError, SyntaxError, ValueError, TypeError, MemoryError):
             # Case 1
             self.showsyntaxerror(filename)
             return None
 
         if code is None:
             # Case 2
             return True
 
         # Case 3
         # We store the code object so that threaded shells and
         # custom exception handlers can access all this info if needed.
         # The source corresponding to this can be obtained from the
         # buffer attribute as '\n'.join(self.buffer).
         self.code_to_run = code
         # now actually execute the code object
         if self.runcode(code) == 0:
             return False
         else:
             return None
 
     def runcode(self,code_obj):
         """Execute a code object.
 
         When an exception occurs, self.showtraceback() is called to display a
         traceback.
 
         Return value: a flag indicating whether the code to be run completed
         successfully:
 
           - 0: successful execution.
           - 1: 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_runcode_hook()
                 exec code_obj in self.user_global_ns, self.user_ns
             finally:
                 # Reset our crash handler in place
                 sys.excepthook = old_excepthook
         except SystemExit:
             self.resetbuffer()
             self.showtraceback()
             warn("Type %exit or %quit to exit IPython "
                  "(%Exit or %Quit do so unconditionally).",level=1)
         except self.custom_exceptions:
             etype,value,tb = sys.exc_info()
             self.CustomTB(etype,value,tb)
         except:
             self.showtraceback()
         else:
             outflag = 0
             if softspace(sys.stdout, 0):
                 print
         # Flush out code object which has been run (and source)
         self.code_to_run = None
         return outflag
         
     def push_line(self, line):
         """Push a line to the interpreter.
 
         The line should not have a trailing newline; it may have
         internal newlines.  The line is appended to a buffer and the
         interpreter's runsource() method is called with the
         concatenated contents of the buffer as source.  If this
         indicates that the command was executed or invalid, the buffer
         is reset; otherwise, the command is incomplete, and the buffer
         is left as it was after the line was appended.  The return
         value is 1 if more input is required, 0 if the line was dealt
         with in some way (this is the same as runsource()).
         """
 
         # autoindent management should be done here, and not in the
         # interactive loop, since that one is only seen by keyboard input.  We
         # need this done correctly even for code run via runlines (which uses
         # push).
 
         #print 'push line: <%s>' % line  # dbg
         for subline in line.splitlines():
             self._autoindent_update(subline)
         self.buffer.append(line)
         more = self.runsource('\n'.join(self.buffer), self.filename)
         if not more:
             self.resetbuffer()
         return more
 
     def _autoindent_update(self,line):
         """Keep track of the indent level."""
 
         #debugx('line')
         #debugx('self.indent_current_nsp')
         if self.autoindent:
             if line:
                 inisp = num_ini_spaces(line)
                 if inisp < self.indent_current_nsp:
                     self.indent_current_nsp = inisp
 
                 if line[-1] == ':':
                     self.indent_current_nsp += 4
                 elif dedent_re.match(line):
                     self.indent_current_nsp -= 4
             else:
                 self.indent_current_nsp = 0
 
     def resetbuffer(self):
         """Reset the input buffer."""
         self.buffer[:] = []
         
     def raw_input(self,prompt='',continue_prompt=False):
         """Write a prompt and read a line.
 
         The returned line does not include the trailing newline.
         When the user enters the EOF key sequence, EOFError is raised.
 
         Optional inputs:
 
           - prompt(''): a string to be printed to prompt the user.
 
           - continue_prompt(False): whether this line is the first one or a
           continuation in a sequence of inputs.
         """
         # growl.notify("raw_input: ", "prompt = %r\ncontinue_prompt = %s" % (prompt, continue_prompt))
 
         # Code run by the user may have modified the readline completer state.
         # We must ensure that our completer is back in place.
 
         if self.has_readline:
             self.set_completer()
         
         try:
             line = raw_input_original(prompt).decode(self.stdin_encoding)
         except ValueError:
             warn("\n********\nYou or a %run:ed script called sys.stdin.close()"
                  " or sys.stdout.close()!\nExiting IPython!")
             self.ask_exit()
             return ""
 
         # Try to be reasonably smart about not re-indenting pasted input more
         # than necessary.  We do this by trimming out the auto-indent initial
         # spaces, if the user's actual input started itself with whitespace.
         #debugx('self.buffer[-1]')
 
         if self.autoindent:
             if num_ini_spaces(line) > self.indent_current_nsp:
                 line = line[self.indent_current_nsp:]
                 self.indent_current_nsp = 0
             
         # store the unfiltered input before the user has any chance to modify
         # it.
         if line.strip():
             if continue_prompt:
                 self.input_hist_raw[-1] += '%s\n' % line
                 if self.has_readline and self.readline_use:
                     try:
                         histlen = self.readline.get_current_history_length()
                         if histlen > 1:
                             newhist = self.input_hist_raw[-1].rstrip()
                             self.readline.remove_history_item(histlen-1)
                             self.readline.replace_history_item(histlen-2,
                                             newhist.encode(self.stdin_encoding))
                     except AttributeError:
                         pass # re{move,place}_history_item are new in 2.4.                
             else:
                 self.input_hist_raw.append('%s\n' % line)                
             # only entries starting at first column go to shadow history
             if line.lstrip() == line:
                 self.shadowhist.add(line.strip())
         elif not continue_prompt:
             self.input_hist_raw.append('\n')
         try:
             lineout = self.prefilter_manager.prefilter_lines(line,continue_prompt)
         except:
             # blanket except, in case a user-defined prefilter crashes, so it
             # can't take all of ipython with it.
             self.showtraceback()
             return ''
         else:
             return lineout
 
     #-------------------------------------------------------------------------
     # Working with components
     #-------------------------------------------------------------------------
 
     def get_component(self, name=None, klass=None):
         """Fetch a component by name and klass in my tree."""
         c = Component.get_instances(root=self, name=name, klass=klass)
+        if len(c) == 0:
+            return None
         if len(c) == 1:
             return c[0]
         else:
             return c
 
     #-------------------------------------------------------------------------
     # IPython extensions
     #-------------------------------------------------------------------------
 
     def load_extension(self, module_str):
         """Load an IPython extension by its module name.
 
         An IPython extension is an importable Python module that has
         a function with the signature::
 
             def load_ipython_extension(ipython):
                 # Do things with ipython
 
         This function is called after your extension is imported and the 
         currently active :class:`InteractiveShell` instance is passed as
         the only argument.  You can do anything you want with IPython at
         that point, including defining new magic and aliases, adding new
         components, etc.
 
         The :func:`load_ipython_extension` will be called again is you 
         load or reload the extension again.  It is up to the extension
         author to add code to manage that.
 
         You can put your extension modules anywhere you want, as long as
         they can be imported by Python's standard import mechanism.  However,
         to make it easy to write extensions, you can also put your extensions
         in ``os.path.join(self.ipythondir, 'extensions')``.  This directory
         is added to ``sys.path`` automatically.
         """
         from IPython.utils.syspathcontext import prepended_to_syspath
 
         if module_str not in sys.modules:
             with prepended_to_syspath(self.ipython_extension_dir):
                 __import__(module_str)
         mod = sys.modules[module_str]
         self._call_load_ipython_extension(mod)
 
     def unload_extension(self, module_str):
         """Unload an IPython extension by its module name.
 
         This function looks up the extension's name in ``sys.modules`` and
         simply calls ``mod.unload_ipython_extension(self)``.
         """
         if module_str in sys.modules:
             mod = sys.modules[module_str]
             self._call_unload_ipython_extension(mod)
 
     def reload_extension(self, module_str):
         """Reload an IPython extension by calling reload.
 
         If the module has not been loaded before,
         :meth:`InteractiveShell.load_extension` is called. Otherwise
         :func:`reload` is called and then the :func:`load_ipython_extension`
         function of the module, if it exists is called.
         """
         from IPython.utils.syspathcontext import prepended_to_syspath
 
         with prepended_to_syspath(self.ipython_extension_dir):
             if module_str in sys.modules:
                 mod = sys.modules[module_str]
                 reload(mod)
                 self._call_load_ipython_extension(mod)
             else:
                 self.load_extension(module_str)
 
     def _call_load_ipython_extension(self, mod):
         if hasattr(mod, 'load_ipython_extension'):
             mod.load_ipython_extension(self)
 
     def _call_unload_ipython_extension(self, mod):
         if hasattr(mod, 'unload_ipython_extension'):
             mod.unload_ipython_extension(self)
 
     #-------------------------------------------------------------------------
     # Things related to the prefilter
     #-------------------------------------------------------------------------
 
     def init_prefilter(self):
         self.prefilter_manager = PrefilterManager(self, config=self.config)
 
     #-------------------------------------------------------------------------
     # Utilities
     #-------------------------------------------------------------------------
 
     def getoutput(self, cmd):
         return getoutput(self.var_expand(cmd,depth=2),
                          header=self.system_header,
                          verbose=self.system_verbose)
 
     def getoutputerror(self, cmd):
         return getoutputerror(self.var_expand(cmd,depth=2),
                               header=self.system_header,
                               verbose=self.system_verbose)
 
     def var_expand(self,cmd,depth=0):
         """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.
         """
 
         return str(ItplNS(cmd,
                           self.user_ns,  # globals
                           # Skip our own frame in searching for locals:
                           sys._getframe(depth+1).f_locals # locals
                           ))
 
     def mktempfile(self,data=None):
         """Make a new tempfile and return its filename.
 
         This makes a call to tempfile.mktemp, 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."""
 
         filename = tempfile.mktemp('.py','ipython_edit_')
         self.tempfiles.append(filename)
         
         if data:
             tmp_file = open(filename,'w')
             tmp_file.write(data)
             tmp_file.close()
         return filename
 
     def write(self,data):
         """Write a string to the default output"""
         Term.cout.write(data)
 
     def write_err(self,data):
         """Write a string to the default error output"""
         Term.cerr.write(data)
 
     def ask_yes_no(self,prompt,default=True):
         if self.quiet:
             return True
         return ask_yes_no(prompt,default)
 
     #-------------------------------------------------------------------------
     # Things related to IPython exiting
     #-------------------------------------------------------------------------
 
     def ask_exit(self):
         """ Call for exiting. Can be overiden and used as a callback. """
         self.exit_now = True
 
     def exit(self):
         """Handle interactive exit.
 
         This method calls the ask_exit callback."""
         if self.confirm_exit:
             if self.ask_yes_no('Do you really want to exit ([y]/n)?','y'):
                 self.ask_exit()
         else:
             self.ask_exit()
 
     def atexit_operations(self):
         """This will be executed at the time of exit.
 
         Saving of persistent data should be performed here.
         """
         self.savehist()
 
         # Cleanup all tempfiles left around
         for tfile in self.tempfiles:
             try:
                 os.unlink(tfile)
             except OSError:
                 pass
 
         # Clear all user namespaces to release all references cleanly.
         self.reset()
 
         # Run user hooks
         self.hooks.shutdown_hook()
 
     def cleanup(self):
         self.restore_sys_module_state()
 
 

IPython/kernel/multiengineclient.py

@@ -1,963 +1,967 b''
 # encoding: utf-8
 # -*- test-case-name: IPython.kernel.test.test_multiengineclient -*-
 
 """General Classes for IMultiEngine clients."""
 
 __docformat__ = "restructuredtext en"
 
 #-------------------------------------------------------------------------------
 #  Copyright (C) 2008  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-------------------------------------------------------------------------------
 
 #-------------------------------------------------------------------------------
 # Imports
 #-------------------------------------------------------------------------------
 
 import sys
 import linecache
 import warnings
 
 from twisted.python import components
 from twisted.python.failure import Failure
 from zope.interface import Interface, implements, Attribute
 
 from IPython.utils.coloransi import TermColors
 
 from IPython.kernel.twistedutil import blockingCallFromThread
 from IPython.kernel import error
 from IPython.kernel.parallelfunction import ParallelFunction
 from IPython.kernel.mapper import (
     MultiEngineMapper, 
     IMultiEngineMapperFactory,
     IMapper
 )
 
 from IPython.kernel.multiengine import IFullSynchronousMultiEngine
 
 
 #-------------------------------------------------------------------------------
 # Pending Result things
 #-------------------------------------------------------------------------------
 
 class IPendingResult(Interface):
     """A representation of a result that is pending.
     
     This class is similar to Twisted's `Deferred` object, but is designed to be
     used in a synchronous context.
     """
     
     result_id=Attribute("ID of the deferred on the other side")
     client=Attribute("A client that I came from")
     r=Attribute("An attribute that is a property that calls and returns get_result")
     
     def get_result(default=None, block=True):
         """
         Get a result that is pending.
                 
         :Parameters:
             default
                 The value to return if the result is not ready.
             block : boolean
                 Should I block for the result.
                 
         :Returns: The actual result or the default value.
         """
         
     def add_callback(f, *args, **kwargs):
         """
         Add a callback that is called with the result.
         
         If the original result is foo, adding a callback will cause
         f(foo, *args, **kwargs) to be returned instead.  If multiple
         callbacks are registered, they are chained together: the result of
         one is passed to the next and so on.  
         
         Unlike Twisted's Deferred object, there is no errback chain.  Thus
         any exception raised will not be caught and handled.  User must 
         catch these by hand when calling `get_result`.
         """
 
 
 class PendingResult(object):
     """A representation of a result that is not yet ready.
     
     A user should not create a `PendingResult` instance by hand.
     
     Methods:
     
     * `get_result`
     * `add_callback`
     
     Properties:
     
     * `r`
     """
     
     def __init__(self, client, result_id):
         """Create a PendingResult with a result_id and a client instance.
         
         The client should implement `_getPendingResult(result_id, block)`.
         """
         self.client = client
         self.result_id = result_id
         self.called = False
         self.raised = False
         self.callbacks = []
         
     def get_result(self, default=None, block=True):
         """Get a result that is pending.
                 
         This method will connect to an IMultiEngine adapted controller
         and see if the result is ready.  If the action triggers an exception
         raise it and record it.  This method records the result/exception once it is 
         retrieved.  Calling `get_result` again will get this cached result or will
         re-raise the exception.  The .r attribute is a property that calls
         `get_result` with block=True.
         
         :Parameters:
             default
                 The value to return if the result is not ready.
             block : boolean
                 Should I block for the result.
                 
         :Returns: The actual result or the default value.
         """
         
         if self.called:
             if self.raised:
                 raise self.result[0], self.result[1], self.result[2]
             else:
                 return self.result
         try:
             result = self.client.get_pending_deferred(self.result_id, block)
         except error.ResultNotCompleted:
             return default
         except:
             # Reraise other error, but first record them so they can be reraised
             # later if .r or get_result is called again.
             self.result = sys.exc_info()
             self.called = True
             self.raised = True
             raise
         else:
             for cb in self.callbacks:
                 result = cb[0](result, *cb[1], **cb[2])
             self.result = result
             self.called = True
             return result
         
     def add_callback(self, f, *args, **kwargs):
         """Add a callback that is called with the result.
         
         If the original result is result, adding a callback will cause
         f(result, *args, **kwargs) to be returned instead.  If multiple
         callbacks are registered, they are chained together: the result of
         one is passed to the next and so on.  
         
         Unlike Twisted's Deferred object, there is no errback chain.  Thus
         any exception raised will not be caught and handled.  User must 
         catch these by hand when calling `get_result`.
         """
         assert callable(f)
         self.callbacks.append((f, args, kwargs))
         
     def __cmp__(self, other):
         if self.result_id < other.result_id:
             return -1
         else:
             return 1
             
     def _get_r(self):
         return self.get_result(block=True)
     
     r = property(_get_r)
     """This property is a shortcut to a `get_result(block=True)`."""
 
 
 #-------------------------------------------------------------------------------
 # Pretty printing wrappers for certain lists
 #-------------------------------------------------------------------------------    
     
 class ResultList(list):
     """A subclass of list that pretty prints the output of `execute`/`get_result`."""
     
     def __repr__(self):
         output = []
         # These colored prompts were not working on Windows
         if sys.platform == 'win32':
             blue = normal = red = green = ''
         else:
             blue = TermColors.Blue
             normal = TermColors.Normal
             red = TermColors.Red
             green = TermColors.Green
         output.append("<Results List>\n")
         for cmd in self:
             if isinstance(cmd, Failure):
                 output.append(cmd)
             else:
                 target = cmd.get('id',None)
                 cmd_num = cmd.get('number',None)
                 cmd_stdin = cmd.get('input',{}).get('translated','No Input')
                 cmd_stdout = cmd.get('stdout', None)
                 cmd_stderr = cmd.get('stderr', None)
                 output.append("%s[%i]%s In [%i]:%s %s\n" % \
                     (green, target,
                     blue, cmd_num, normal, cmd_stdin))
                 if cmd_stdout:
                     output.append("%s[%i]%s Out[%i]:%s %s\n" % \
                         (green, target,
                         red, cmd_num, normal, cmd_stdout))
                 if cmd_stderr:
                     output.append("%s[%i]%s Err[%i]:\n%s %s" % \
                         (green, target,
                         red, cmd_num, normal, cmd_stderr))
         return ''.join(output)
 
 
 def wrapResultList(result):
     """A function that wraps the output of `execute`/`get_result` -> `ResultList`."""
     if len(result) == 0:
         result = [result]
     return ResultList(result)
 
 
 class QueueStatusList(list):
     """A subclass of list that pretty prints the output of `queue_status`."""
     
     def __repr__(self):
         output = []
         output.append("<Queue Status List>\n")
         for e in self:
             output.append("Engine: %s\n" % repr(e[0]))
             output.append("    Pending: %s\n" % repr(e[1]['pending']))
             for q in e[1]['queue']:
                 output.append("    Command: %s\n" % repr(q))
         return ''.join(output)
 
 
 #-------------------------------------------------------------------------------
 # InteractiveMultiEngineClient
 #-------------------------------------------------------------------------------    
 
 class InteractiveMultiEngineClient(object):
     """A mixin class that add a few methods to a multiengine client.
     
     The methods in this mixin class are designed for interactive usage.
     """
                                         
     def activate(self):
         """Make this `MultiEngineClient` active for parallel magic commands.
         
         IPython has a magic command syntax to work with `MultiEngineClient` objects.
         In a given IPython session there is a single active one.  While
         there can be many `MultiEngineClient` created and used by the user, 
         there is only one active one.  The active `MultiEngineClient` is used whenever 
         the magic commands %px and %autopx are used.
         
         The activate() method is called on a given `MultiEngineClient` to make it 
         active.  Once this has been done, the magic commands can be used.
         """
         
         try:
             # This is injected into __builtins__.
             ip = get_ipython()
         except NameError:
             print "The IPython parallel magics (%result, %px, %autopx) only work within IPython."
         else:
             pmagic = ip.get_component('parallel_magic')
+            if pmagic is not None:
             pmagic.active_multiengine_client = self
+            else:
+                print "You must first load the parallelmagic extension " \
+                      "by doing '%load_ext parallelmagic'"
                     
     def __setitem__(self, key, value):
         """Add a dictionary interface for pushing/pulling.
         
         This functions as a shorthand for `push`.
         
         :Parameters:
             key : str 
                 What to call the remote object.
             value : object
                 The local Python object to push.
         """
         targets, block = self._findTargetsAndBlock()
         return self.push({key:value}, targets=targets, block=block)
     
     def __getitem__(self, key):
         """Add a dictionary interface for pushing/pulling.
         
         This functions as a shorthand to `pull`.
         
         :Parameters:
          - `key`: A string representing the key.
         """
         if isinstance(key, str):
             targets, block = self._findTargetsAndBlock()
             return self.pull(key, targets=targets, block=block)
         else:
             raise TypeError("__getitem__ only takes strs")
             
     def __len__(self):
         """Return the number of available engines."""
         return len(self.get_ids())
     
     #---------------------------------------------------------------------------
     # Make this a context manager for with
     #---------------------------------------------------------------------------
     
     def findsource_file(self,f):
         linecache.checkcache()
         s = findsource(f.f_code) # findsource is not defined!
         lnum = f.f_lineno
         wsource = s[0][f.f_lineno:]
         return strip_whitespace(wsource)
 
     def findsource_ipython(self,f):
         from IPython.core import ipapi
         self.ip = ipapi.get()
         wsource = [l+'\n' for l in
                    self.ip.input_hist_raw[-1].splitlines()[1:]] 
         return strip_whitespace(wsource)
         
     def __enter__(self):
         f = sys._getframe(1)
         local_ns = f.f_locals
         global_ns = f.f_globals
         if f.f_code.co_filename == '<ipython console>':
             s = self.findsource_ipython(f)
         else:
             s = self.findsource_file(f)
 
         self._with_context_result = self.execute(s)
 
     def __exit__ (self, etype, value, tb):
         if issubclass(etype,error.StopLocalExecution):
             return True
 
 
 def remote():
     m = 'Special exception to stop local execution of parallel code.'
     raise error.StopLocalExecution(m)
 
 def strip_whitespace(source):
     # Expand tabs to avoid any confusion.
     wsource = [l.expandtabs(4) for l in source]
     # Detect the indentation level
     done = False
     for line in wsource:
         if line.isspace():
             continue
         for col,char in enumerate(line):
             if char != ' ':
                 done = True
                 break
         if done:
             break
     # Now we know how much leading space there is in the code.  Next, we
     # extract up to the first line that has less indentation.
     # WARNINGS: we skip comments that may be misindented, but we do NOT yet
     # detect triple quoted strings that may have flush left text.
     for lno,line in enumerate(wsource):
         lead = line[:col]
         if lead.isspace():
             continue
         else:
             if not lead.lstrip().startswith('#'):
                 break
     # The real 'with' source is up to lno
     src_lines = [l[col:] for l in wsource[:lno+1]]
 
     # Finally, check that the source's first non-comment line begins with the
     # special call 'remote()'
     for nline,line in enumerate(src_lines):
         if line.isspace() or line.startswith('#'):
             continue
         if 'remote()' in line:
             break
         else:
             raise ValueError('remote() call missing at the start of code')
     src = ''.join(src_lines[nline+1:])
     #print 'SRC:\n<<<<<<<>>>>>>>\n%s<<<<<>>>>>>' % src  # dbg
     return src
 
 
 #-------------------------------------------------------------------------------
 # The top-level MultiEngine client adaptor
 #-------------------------------------------------------------------------------
 
 
 _prop_warn = """\
 
 We are currently refactoring the task dependency system.  This might
 involve the removal of this method and other methods related to engine
 properties.  Please see the docstrings for IPython.kernel.TaskRejectError 
 for more information."""
 
 
 class IFullBlockingMultiEngineClient(Interface):
     pass
 
 
 class FullBlockingMultiEngineClient(InteractiveMultiEngineClient):
     """
     A blocking client to the `IMultiEngine` controller interface.
     
     This class allows users to use a set of engines for a parallel
     computation through the `IMultiEngine` interface.  In this interface,
     each engine has a specific id (an int) that is used to refer to the
     engine, run code on it, etc.
     """
     
     implements(
         IFullBlockingMultiEngineClient,
         IMultiEngineMapperFactory,
         IMapper
     )
     
     def __init__(self, smultiengine):
         self.smultiengine = smultiengine
         self.block = True
         self.targets = 'all'
     
     def _findBlock(self, block=None):
         if block is None:
             return self.block
         else:
             if block in (True, False):
                 return block
             else:
                 raise ValueError("block must be True or False")
     
     def _findTargets(self, targets=None):
         if targets is None:
             return self.targets
         else:
             if not isinstance(targets, (str,list,tuple,int)):
                 raise ValueError("targets must be a str, list, tuple or int")
             return targets
     
     def _findTargetsAndBlock(self, targets=None, block=None):
         return self._findTargets(targets), self._findBlock(block) 
     
     def _blockFromThread(self, function, *args, **kwargs):
         block = kwargs.get('block', None)
         if block is None:
             raise error.MissingBlockArgument("'block' keyword argument is missing")
         result = blockingCallFromThread(function, *args, **kwargs)
         if not block:
             result = PendingResult(self, result)
         return result
     
     def get_pending_deferred(self, deferredID, block):
         return blockingCallFromThread(self.smultiengine.get_pending_deferred, deferredID, block)
     
     def barrier(self, pendingResults):
         """Synchronize a set of `PendingResults`.
         
         This method is a synchronization primitive that waits for a set of
         `PendingResult` objects to complete.  More specifically, barier does
         the following.
         
         * The `PendingResult`s are sorted by result_id.
         * The `get_result` method is called for each `PendingResult` sequentially
           with block=True.
         * If a `PendingResult` gets a result that is an exception, it is 
           trapped and can be re-raised later by calling `get_result` again.
         * The `PendingResult`s are flushed from the controller.
                 
         After barrier has been called on a `PendingResult`, its results can 
         be retrieved by calling `get_result` again or accesing the `r` attribute
         of the instance.
         """
         
         # Convert to list for sorting and check class type 
         prList = list(pendingResults)
         for pr in prList:
             if not isinstance(pr, PendingResult):
                 raise error.NotAPendingResult("Objects passed to barrier must be PendingResult instances")
                             
         # Sort the PendingResults so they are in order
         prList.sort()
         # Block on each PendingResult object
         for pr in prList:
             try:
                 result = pr.get_result(block=True)
             except Exception:
                 pass
     
     def flush(self):
         """
         Clear all pending deferreds/results from the controller.
         
         For each `PendingResult` that is created by this client, the controller
         holds on to the result for that `PendingResult`.  This can be a problem
         if there are a large number of `PendingResult` objects that are created.
         
         Once the result of the `PendingResult` has been retrieved, the result
         is removed from the controller, but if a user doesn't get a result (
         they just ignore the `PendingResult`) the result is kept forever on the
         controller.  This method allows the user to clear out all un-retrieved
         results on the controller. 
         """
         r = blockingCallFromThread(self.smultiengine.clear_pending_deferreds)
         return r
     
     clear_pending_results = flush
     
     #---------------------------------------------------------------------------
     # IEngineMultiplexer related methods
     #---------------------------------------------------------------------------
     
     def execute(self, lines, targets=None, block=None):
         """
         Execute code on a set of engines.
         
         :Parameters:
             lines : str
                 The Python code to execute as a string
             targets : id or list of ids
                 The engine to use for the execution
             block : boolean
                 If False, this method will return the actual result.  If False,
                 a `PendingResult` is returned which can be used to get the result
                 at a later time.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         result = blockingCallFromThread(self.smultiengine.execute, lines,
             targets=targets, block=block)
         if block:
             result = ResultList(result)
         else:
             result = PendingResult(self, result)
             result.add_callback(wrapResultList)
         return result
     
     def push(self, namespace, targets=None, block=None):
         """
         Push a dictionary of keys and values to engines namespace.
         
         Each engine has a persistent namespace.  This method is used to push
         Python objects into that namespace.
         
         The objects in the namespace must be pickleable.
         
         :Parameters:
             namespace : dict
                 A dict that contains Python objects to be injected into
                 the engine persistent namespace.
             targets : id or list of ids
                 The engine to use for the execution
             block : boolean
                 If False, this method will return the actual result.  If False,
                 a `PendingResult` is returned which can be used to get the result
                 at a later time.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.push, namespace,
             targets=targets, block=block)
     
     def pull(self, keys, targets=None, block=None):
         """
         Pull Python objects by key out of engines namespaces.
         
         :Parameters:
             keys : str or list of str
                 The names of the variables to be pulled
             targets : id or list of ids
                 The engine to use for the execution
             block : boolean
                 If False, this method will return the actual result.  If False,
                 a `PendingResult` is returned which can be used to get the result
                 at a later time.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.pull, keys, targets=targets, block=block)
     
     def push_function(self, namespace, targets=None, block=None):
         """
         Push a Python function to an engine.
         
         This method is used to push a Python function to an engine.  This
         method can then be used in code on the engines.  Closures are not supported.
         
         :Parameters:
             namespace : dict
                 A dict whose values are the functions to be pushed.  The keys give
                 that names that the function will appear as in the engines
                 namespace.
             targets : id or list of ids
                 The engine to use for the execution
             block : boolean
                 If False, this method will return the actual result.  If False,
                 a `PendingResult` is returned which can be used to get the result
                 at a later time.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.push_function, namespace, targets=targets, block=block)
     
     def pull_function(self, keys, targets=None, block=None):
         """
         Pull a Python function from an engine.
         
         This method is used to pull a Python function from an engine.
         Closures are not supported.
         
         :Parameters:
             keys : str or list of str
                 The names of the functions to be pulled
             targets : id or list of ids
                 The engine to use for the execution
             block : boolean
                 If False, this method will return the actual result.  If False,
                 a `PendingResult` is returned which can be used to get the result
                 at a later time.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.pull_function, keys, targets=targets, block=block)
     
     def push_serialized(self, namespace, targets=None, block=None):
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.push_serialized, namespace, targets=targets, block=block)
     
     def pull_serialized(self, keys, targets=None, block=None):
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.pull_serialized, keys, targets=targets, block=block)
     
     def get_result(self, i=None, targets=None, block=None):
         """
         Get a previous result.
         
         When code is executed in an engine, a dict is created and returned.  This
         method retrieves that dict for previous commands.
         
         :Parameters:
             i : int
                 The number of the result to get
             targets : id or list of ids
                 The engine to use for the execution
             block : boolean
                 If False, this method will return the actual result.  If False,
                 a `PendingResult` is returned which can be used to get the result
                 at a later time.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         result = blockingCallFromThread(self.smultiengine.get_result, i, targets=targets, block=block)
         if block:
             result = ResultList(result)
         else:
             result = PendingResult(self, result)
             result.add_callback(wrapResultList)
         return result
     
     def reset(self, targets=None, block=None):
         """
         Reset an engine.
         
         This method clears out the namespace of an engine.
 
         :Parameters:
             targets : id or list of ids
                 The engine to use for the execution
             block : boolean
                 If False, this method will return the actual result.  If False,
                 a `PendingResult` is returned which can be used to get the result
                 at a later time.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.reset, targets=targets, block=block)
     
     def keys(self, targets=None, block=None):
         """
         Get a list of all the variables in an engine's namespace.
 
         :Parameters:
             targets : id or list of ids
                 The engine to use for the execution
             block : boolean
                 If False, this method will return the actual result.  If False,
                 a `PendingResult` is returned which can be used to get the result
                 at a later time.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.keys, targets=targets, block=block)
     
     def kill(self, controller=False, targets=None, block=None):
         """
         Kill the engines and controller.
         
         This method is used to stop the engine and controller by calling
         `reactor.stop`.
         
         :Parameters:
             controller : boolean
                 If True, kill the engines and controller.  If False, just the 
                 engines
             targets : id or list of ids
                 The engine to use for the execution
             block : boolean
                 If False, this method will return the actual result.  If False,
                 a `PendingResult` is returned which can be used to get the result
                 at a later time.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.kill, controller, targets=targets, block=block)
     
     def clear_queue(self, targets=None, block=None):
         """
         Clear out the controller's queue for an engine.
         
         The controller maintains a queue for each engine.  This clear it out.
         
         :Parameters:
             targets : id or list of ids
                 The engine to use for the execution
             block : boolean
                 If False, this method will return the actual result.  If False,
                 a `PendingResult` is returned which can be used to get the result
                 at a later time.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.clear_queue, targets=targets, block=block)
     
     def queue_status(self, targets=None, block=None):
         """
         Get the status of an engines queue.
         
         :Parameters:
             targets : id or list of ids
                 The engine to use for the execution
             block : boolean
                 If False, this method will return the actual result.  If False,
                 a `PendingResult` is returned which can be used to get the result
                 at a later time.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.queue_status, targets=targets, block=block)
     
     def set_properties(self, properties, targets=None, block=None):
         warnings.warn(_prop_warn)
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.set_properties, properties, targets=targets, block=block)
     
     def get_properties(self, keys=None, targets=None, block=None):
         warnings.warn(_prop_warn)
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.get_properties, keys, targets=targets, block=block)
     
     def has_properties(self, keys, targets=None, block=None):
         warnings.warn(_prop_warn)
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.has_properties, keys, targets=targets, block=block)
     
     def del_properties(self, keys, targets=None, block=None):
         warnings.warn(_prop_warn)
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.del_properties, keys, targets=targets, block=block)
     
     def clear_properties(self, targets=None, block=None):
         warnings.warn(_prop_warn)
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.clear_properties, targets=targets, block=block)
     
     #---------------------------------------------------------------------------
     # IMultiEngine related methods
     #---------------------------------------------------------------------------
     
     def get_ids(self):
         """
         Returns the ids of currently registered engines.
         """
         result = blockingCallFromThread(self.smultiengine.get_ids)
         return result
         
     #---------------------------------------------------------------------------
     # IMultiEngineCoordinator
     #---------------------------------------------------------------------------
              
     def scatter(self, key, seq, dist='b', flatten=False, targets=None, block=None):
         """
         Partition a Python sequence and send the partitions to a set of engines.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.scatter, key, seq, 
             dist, flatten, targets=targets, block=block)
     
     def gather(self, key, dist='b', targets=None, block=None):
         """
         Gather a partitioned sequence on a set of engines as a single local seq.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.gather, key, dist, 
             targets=targets, block=block)
     
     def raw_map(self, func, seq, dist='b', targets=None, block=None):
         """
         A parallelized version of Python's builtin map.
         
         This has a slightly different syntax than the builtin `map`.
         This is needed because we need to have keyword arguments and thus
         can't use *args to capture all the sequences.  Instead, they must
         be passed in a list or tuple.
         
         raw_map(func, seqs) -> map(func, seqs[0], seqs[1], ...)
         
         Most users will want to use parallel functions or the `mapper`
         and `map` methods for an API that follows that of the builtin
         `map`.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.raw_map, func, seq, 
             dist, targets=targets, block=block)
     
     def map(self, func, *sequences):
         """
         A parallel version of Python's builtin `map` function.
         
         This method applies a function to sequences of arguments.  It 
         follows the same syntax as the builtin `map`.
         
         This method creates a mapper objects by calling `self.mapper` with
         no arguments and then uses that mapper to do the mapping.  See
         the documentation of `mapper` for more details.
         """
         return self.mapper().map(func, *sequences)
     
     def mapper(self, dist='b', targets='all', block=None):
         """
         Create a mapper object that has a `map` method.
         
         This method returns an object that implements the `IMapper` 
         interface.  This method is a factory that is used to control how 
         the map happens.
         
         :Parameters:
             dist : str
                 What decomposition to use, 'b' is the only one supported
                 currently
             targets : str, int, sequence of ints
                 Which engines to use for the map
             block : boolean
                 Should calls to `map` block or not
         """
         return MultiEngineMapper(self, dist, targets, block)
     
     def parallel(self, dist='b', targets=None, block=None):
         """
         A decorator that turns a function into a parallel function.
         
         This can be used as:
         
         @parallel()
         def f(x, y)
             ...
         
         f(range(10), range(10))
         
         This causes f(0,0), f(1,1), ... to be called in parallel.
         
         :Parameters:
             dist : str
                 What decomposition to use, 'b' is the only one supported
                 currently
             targets : str, int, sequence of ints
                 Which engines to use for the map
             block : boolean
                 Should calls to `map` block or not
         """
         targets, block = self._findTargetsAndBlock(targets, block)       
         mapper = self.mapper(dist, targets, block)
         pf = ParallelFunction(mapper)
         return pf
     
     #---------------------------------------------------------------------------
     # IMultiEngineExtras
     #---------------------------------------------------------------------------
     
     def zip_pull(self, keys, targets=None, block=None):
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.zip_pull, keys, 
             targets=targets, block=block)
     
     def run(self, filename, targets=None, block=None):
         """
         Run a Python code in a file on the engines.
         
         :Parameters:
             filename : str
                 The name of the local file to run
             targets : id or list of ids
                 The engine to use for the execution
             block : boolean
                 If False, this method will return the actual result.  If False,
                 a `PendingResult` is returned which can be used to get the result
                 at a later time.
         """
         targets, block = self._findTargetsAndBlock(targets, block)
         return self._blockFromThread(self.smultiengine.run, filename,
             targets=targets, block=block)
     
     def benchmark(self, push_size=10000):
         """
         Run performance benchmarks for the current IPython cluster.
         
         This method tests both the latency of sending command and data to the
         engines as well as the throughput of sending large objects to the
         engines using push.  The latency is measured by having one or more
         engines execute the command 'pass'.  The throughput is measure by 
         sending an NumPy array of size `push_size` to one or more engines.
         
         These benchmarks will vary widely on different hardware and networks
         and thus can be used to get an idea of the performance characteristics
         of a particular configuration of an IPython controller and engines.
         
         This function is not testable within our current testing framework.
         """
         import timeit, __builtin__
         __builtin__._mec_self = self
         benchmarks = {}
         repeat = 3
         count = 10
 
         timer = timeit.Timer('_mec_self.execute("pass",0)')
         result = 1000*min(timer.repeat(repeat,count))/count
         benchmarks['single_engine_latency'] = (result,'msec')
 
         timer = timeit.Timer('_mec_self.execute("pass")')
         result = 1000*min(timer.repeat(repeat,count))/count
         benchmarks['all_engine_latency'] = (result,'msec')
 
         try:
             import numpy as np
         except:
             pass
         else:
             timer = timeit.Timer(
                 "_mec_self.push(d)",
                 "import numpy as np; d = dict(a=np.zeros(%r,dtype='float64'))" % push_size
             )
             result = min(timer.repeat(repeat,count))/count
             benchmarks['all_engine_push'] = (1e-6*push_size*8/result, 'MB/sec')
 
         try:
             import numpy as np
         except:
             pass
         else:
             timer = timeit.Timer(
                 "_mec_self.push(d,0)",
                 "import numpy as np; d = dict(a=np.zeros(%r,dtype='float64'))" % push_size
             )
             result = min(timer.repeat(repeat,count))/count
             benchmarks['single_engine_push'] = (1e-6*push_size*8/result, 'MB/sec')
 
         return benchmarks
 
 
 components.registerAdapter(FullBlockingMultiEngineClient,
             IFullSynchronousMultiEngine, IFullBlockingMultiEngineClient)