Created context manager for the things injected into __builtin__.

IPython/core/builtin_trap.py

@@ -0,0 +1,104 b''
+#!/usr/bin/env python
+# encoding: utf-8
+"""
+A context manager for managing things injected into :mod:`__builtin__`.
+
+Authors:
+
+* Brian Granger
+"""
+
+#-----------------------------------------------------------------------------
+#  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
+#-----------------------------------------------------------------------------
+
+import __builtin__
+
+from IPython.core.component import Component
+from IPython.core.quitter import Quitter
+
+#-----------------------------------------------------------------------------
+# Classes and functions
+#-----------------------------------------------------------------------------
+
+
+class BuiltinUndefined(object): pass
+BuiltinUndefined = BuiltinUndefined()
+
+
+class BuiltinTrap(Component):
+
+    def __init__(self, parent, name=None, config=None):
+        super(BuiltinTrap, self).__init__(parent, name, config)
+        # Don't just grab parent!!!
+        from IPython.core.iplib import InteractiveShell
+        self.shell = InteractiveShell.get_instances(root=self.root)[0]
+        self._orig_builtins = {}
+
+    def __enter__(self):
+        self.set()
+        # I return self, so callers can use add_builtin in a with clause.
+        return self
+
+    def __exit__(self, type, value, traceback):
+        self.unset()
+        return True
+
+    def add_builtin(self, key, value):
+        """Add a builtin and save the original."""
+        orig = __builtin__.__dict__.get(key, BuiltinUndefined)
+        self._orig_builtins[key] = orig
+        __builtin__.__dict__[key] = value
+
+    def remove_builtin(self, key):
+        """Remove an added builtin and re-set the original."""
+        try:
+            orig = self._orig_builtins.pop(key)
+        except KeyError:
+            pass
+        else:
+            if orig is BuiltinUndefined:
+                del __builtin__.__dict__[key]
+            else:
+                __builtin__.__dict__[key] = orig
+
+    def set(self):
+        """Store ipython references in the __builtin__ namespace."""
+        self.add_builtin('exit', Quitter(self.shell, 'exit'))
+        self.add_builtin('quit', Quitter(self.shell, 'quit'))
+
+        # Recursive reload function
+        try:
+            from IPython.lib import deepreload
+            if self.shell.deep_reload:
+                self.add_builtin('reload', deepreload.reload)
+            else:
+                self.add_builtin('dreload', deepreload.reload)
+            del deepreload
+        except ImportError:
+            pass
+
+        # Keep in the builtins a flag for when IPython is active.  We set it
+        # with setdefault so that multiple nested IPythons don't clobber one
+        # another.  Each will increase its value by one upon being activated,
+        # which also gives us a way to determine the nesting level.
+        __builtin__.__dict__.setdefault('__IPYTHON__active',0)
+
+    def unset(self):
+        """Remove any builtins which might have been added by add_builtins, or
+        restore overwritten ones to their previous values."""
+        for key in self._orig_builtins.keys():
+            self.remove_builtin(key)
+        self._orig_builtins.clear()
+        self._builtins_added = False
+        try:
+            del __builtin__.__dict__['__IPYTHON__active']
+        except KeyError:
+            pass
  No newline at end of file

IPython/core/quitter.py

@@ -0,0 +1,38 b''
+#!/usr/bin/env python
+# encoding: utf-8
+"""
+A simple class for quitting IPython.
+
+Authors:
+
+* Brian Granger
+"""
+
+#-----------------------------------------------------------------------------
+#  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
+#-----------------------------------------------------------------------------
+
+
+class Quitter(object):
+    """Simple class to handle exit, similar to Python 2.5's.
+
+    It handles exiting in an ipython-safe manner, which the one in Python 2.5
+    doesn't do (obviously, since it doesn't know about ipython)."""
+    
+    def __init__(self, shell, name):
+        self.shell = shell
+        self.name = name
+        
+    def __repr__(self):
+        return 'Type %s() to exit.' % self.name
+    __str__ = __repr__
+
+    def __call__(self):
+        self.shell.exit()
  No newline at end of file

IPython/core/component.py

@@ -1,233 +1,242 b''
 #!/usr/bin/env python
 # encoding: utf-8
 """
 A lightweight component system for IPython.
 
 Authors:
 
 * Brian Granger
 * Fernando Perez
 """
 
 #-----------------------------------------------------------------------------
 #  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 copy import deepcopy
 import datetime
 from weakref import WeakValueDictionary
 
 from IPython.utils.ipstruct import Struct
 from IPython.utils.traitlets import (
     HasTraitlets, TraitletError, MetaHasTraitlets, Instance, This
 )
 
 
 #-----------------------------------------------------------------------------
 # Helper classes for Components
 #-----------------------------------------------------------------------------
 
 
 class ComponentError(Exception):
     pass
 
 class MetaComponentTracker(type):
     """A metaclass that tracks instances of Components and its subclasses."""
 
     def __init__(cls, name, bases, d):
         super(MetaComponentTracker, cls).__init__(name, bases, d)
         cls.__instance_refs = WeakValueDictionary()
         cls.__numcreated = 0
 
     def __call__(cls, *args, **kw):
         """Called when *class* is called (instantiated)!!!
         
         When a Component or subclass is instantiated, this is called and
         the instance is saved in a WeakValueDictionary for tracking.
         """
-
-        instance = super(MetaComponentTracker, cls).__call__(*args, **kw)
+        instance = cls.__new__(cls, *args, **kw)
+        # Do this before __init__ is called so get_instances works inside
+        # __init__ methods!
         for c in cls.__mro__:
             if issubclass(cls, c) and issubclass(c, Component):
                 c.__numcreated += 1
                 c.__instance_refs[c.__numcreated] = instance
+        if isinstance(instance, cls):
+            cls.__init__(instance, *args, **kw)
+
         return instance
 
-    def get_instances(cls, name=None, root=None):
+    def get_instances(cls, name=None, root=None, classname=None):
         """Get all instances of cls and its subclasses.
 
         Parameters
         ----------
         name : str
             Limit to components with this name.
         root : Component or subclass
             Limit to components having this root.
+        classname : str
+            The string name of a class to match exactly.
         """
         instances = cls.__instance_refs.values()
         if name is not None:
             instances = [i for i in instances if i.name == name]
+        if classname is not None:
+            instances = [i for i in instances if i.__class__.__name__ == classname]
         if root is not None:
             instances = [i for i in instances if i.root == root]
         return instances
 
-    def get_instances_by_condition(cls, call, name=None, root=None):
+    def get_instances_by_condition(cls, call, name=None, root=None,
+                                   classname=None):
         """Get all instances of cls, i such that call(i)==True.
 
-        This also takes the ``name`` and ``root`` arguments of
-        :meth:`get_instance`
+        This also takes the ``name`` and ``root`` and ``classname`` 
+        arguments of :meth:`get_instance`
         """
-        return [i for i in cls.get_instances(name, root) if call(i)]
+        return [i for i in cls.get_instances(name, root, classname) if call(i)]
 
 
 class ComponentNameGenerator(object):
     """A Singleton to generate unique component names."""
 
     def __init__(self, prefix):
         self.prefix = prefix
         self.i = 0
 
     def __call__(self):
         count = self.i
         self.i += 1
         return "%s%s" % (self.prefix, count)
 
 
 ComponentNameGenerator = ComponentNameGenerator('ipython.component')
 
 
 class MetaComponent(MetaHasTraitlets, MetaComponentTracker):
     pass
 
 
 #-----------------------------------------------------------------------------
 # Component implementation
 #-----------------------------------------------------------------------------
 
 
 class Component(HasTraitlets):
 
     __metaclass__ = MetaComponent
 
     # Traitlets are fun!
     config = Instance(Struct,(),{})
     parent = This()
     root = This()
     created = None
 
     def __init__(self, parent, name=None, config=None):
         """Create a component given a parent and possibly and name and config.
 
         Parameters
         ----------
         parent : Component subclass
             The parent in the component graph.  The parent is used
             to get the root of the component graph.
         name : str
             The unique name of the component.  If empty, then a unique
             one will be autogenerated.
         config : Struct
             If this is empty, self.config = parent.config, otherwise
             self.config = config and root.config is ignored.  This argument
             should only be used to *override* the automatic inheritance of 
             parent.config.  If a caller wants to modify parent.config 
             (not override), the caller should make a copy and change 
             attributes and then pass the copy to this argument.
         
         Notes
         -----
         Subclasses of Component must call the :meth:`__init__` method of
         :class:`Component` *before* doing anything else and using 
         :func:`super`::
         
             class MyComponent(Component):
                 def __init__(self, parent, name=None, config=None):
                     super(MyComponent, self).__init__(parent, name, config)
                     # Then any other code you need to finish initialization.
 
         This ensures that the :attr:`parent`, :attr:`name` and :attr:`config`
         attributes are handled properly.
         """
         super(Component, self).__init__()
         self._children = []
         if name is None:
             self.name = ComponentNameGenerator()
         else:
             self.name = name
         self.root = self # This is the default, it is set when parent is set
         self.parent = parent     
         if config is not None:
             self.config = deepcopy(config)
         else:
             if self.parent is not None:
                 self.config = deepcopy(self.parent.config)
 
         self.created = datetime.datetime.now()
 
     #-------------------------------------------------------------------------
     # Static traitlet notifiations
     #-------------------------------------------------------------------------
 
     def _parent_changed(self, name, old, new):
         if old is not None:
             old._remove_child(self)
         if new is not None:
             new._add_child(self)
 
         if new is None:
             self.root = self
         else:
             self.root = new.root
 
     def _root_changed(self, name, old, new):
         if self.parent is None:
             if not (new is self):
                 raise ComponentError("Root not self, but parent is None.")
         else:
             if not self.parent.root is new:
                 raise ComponentError("Error in setting the root attribute: "
                                      "root != parent.root")
 
     def _config_changed(self, name, old, new):
         """Update all the class traits having a config_key with the config.
 
         For any class traitlet with a ``config_key`` metadata attribute, we
         update the traitlet with the value of the corresponding config entry.
 
         In the future, we might want to do a pop here so stale config info
         is not passed onto children.
         """
         # Get all traitlets with a config_key metadata entry
         traitlets = self.traitlets('config_key')
         for k, v in traitlets.items():
             try:
                 config_value = new[v.get_metadata('config_key')]
             except KeyError:
                 pass
             else:
                 setattr(self, k, config_value)
 
     @property
     def children(self):
         """A list of all my child components."""
         return self._children
 
     def _remove_child(self, child):
         """A private method for removing children components."""
         if child in self._children:
             index = self._children.index(child)
             del self._children[index]
 
     def _add_child(self, child):
         """A private method for adding children components."""
         if child not in self._children:
             self._children.append(child)
 
     def __repr__(self):
         return "<Component('%s')>" % self.name

IPython/core/embed.py

@@ -1,215 +1,282 b''
 #!/usr/bin/env python
 # encoding: utf-8
 """
 An embedded IPython shell.
 
 Authors:
 
 * Brian Granger
 * Fernando Perez
 
 Notes
 -----
 """
 
 #-----------------------------------------------------------------------------
 #  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 sys
 
 from IPython.core import ultratb
 from IPython.core.iplib import InteractiveShell
 
 from IPython.utils.traitlets import Bool, Str, CBool
 from IPython.utils.genutils import ask_yes_no
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
 # This is an additional magic that is exposed in embedded shells.
 def kill_embedded(self,parameter_s=''):
     """%kill_embedded : deactivate for good the current embedded IPython.
 
     This function (after asking for confirmation) sets an internal flag so that
     an embedded IPython will never activate again.  This is useful to
     permanently disable a shell that is being called inside a loop: once you've
     figured out what you needed from it, you may then kill it and the program
     will then continue to run without the interactive shell interfering again.
     """
     
     kill = ask_yes_no("Are you sure you want to kill this embedded instance "
                      "(y/n)? [y/N] ",'n')
     if kill:
         self.embedded_active = False
         print "This embedded IPython will not reactivate anymore once you exit."
 
 
 class InteractiveShellEmbed(InteractiveShell):
 
     dummy_mode = Bool(False)
     exit_msg = Str('')
     embedded = CBool(True)
     embedded_active = CBool(True)
 
     def __init__(self, parent=None, config=None, ipythondir=None, usage=None,
                  user_ns=None, user_global_ns=None,
                  banner1=None, banner2=None,
-                 custom_exceptions=((),None), exit_msg=None):
+                 custom_exceptions=((),None), exit_msg=''):
 
         # First we need to save the state of sys.displayhook and
         # sys.ipcompleter so we can restore it when we are done.
         self.save_sys_displayhook()
         self.save_sys_ipcompleter()
 
         super(InteractiveShellEmbed,self).__init__(
             parent=parent, config=config, ipythondir=ipythondir, usage=usage, 
             user_ns=user_ns, user_global_ns=user_global_ns,
             banner1=banner1, banner2=banner2, 
             custom_exceptions=custom_exceptions)
 
         self.save_sys_displayhook_embed()
         self.exit_msg = exit_msg
         self.define_magic("kill_embedded", kill_embedded)
 
         # don't use the ipython crash handler so that user exceptions aren't
         # trapped
         sys.excepthook = ultratb.FormattedTB(color_scheme=self.colors,
                                              mode=self.xmode,
                                              call_pdb=self.pdb)
 
         self.restore_sys_displayhook()
         self.restore_sys_ipcompleter()
 
     def init_sys_modules(self):
         pass
 
     def save_sys_displayhook(self):
         # sys.displayhook is a global, we need to save the user's original
         # Don't rely on __displayhook__, as the user may have changed that.
         self.sys_displayhook_orig = sys.displayhook
 
     def save_sys_ipcompleter(self):
         """Save readline completer status."""
         try:
             #print 'Save completer',sys.ipcompleter  # dbg
             self.sys_ipcompleter_orig = sys.ipcompleter
         except:
             pass # not nested with IPython        
 
     def restore_sys_displayhook(self):
         sys.displayhook = self.sys_displayhook_orig
 
     def restore_sys_ipcompleter(self):
         """Restores the readline completer which was in place.
 
         This allows embedded IPython within IPython not to disrupt the
         parent's completion.
         """
         try:
             self.readline.set_completer(self.sys_ipcompleter_orig)
             sys.ipcompleter = self.sys_ipcompleter_orig
         except:
             pass
 
     def save_sys_displayhook_embed(self):
         self.sys_displayhook_embed = sys.displayhook
 
     def restore_sys_displayhook_embed(self):
         sys.displayhook = self.sys_displayhook_embed
 
     def __call__(self, header='', local_ns=None, global_ns=None, dummy=None,
                  stack_depth=1):
         """Activate the interactive interpreter.
 
         __call__(self,header='',local_ns=None,global_ns,dummy=None) -> Start
         the interpreter shell with the given local and global namespaces, and
         optionally print a header string at startup.
 
         The shell can be globally activated/deactivated using the
         set/get_dummy_mode methods. This allows you to turn off a shell used
         for debugging globally.
 
         However, *each* time you call the shell you can override the current
         state of dummy_mode with the optional keyword parameter 'dummy'. For
         example, if you set dummy mode on with IPShell.set_dummy_mode(1), you
         can still have a specific call work by making it as IPShell(dummy=0).
 
         The optional keyword parameter dummy controls whether the call
         actually does anything.
         """
 
         # If the user has turned it off, go away
         if not self.embedded_active:
             return
 
         # Normal exits from interactive mode set this flag, so the shell can't
         # re-enter (it checks this variable at the start of interactive mode).
         self.exit_now = False
 
         # Allow the dummy parameter to override the global __dummy_mode
         if dummy or (dummy != 0 and self.dummy_mode):
             return
 
         self.restore_sys_displayhook_embed()
 
         if self.has_readline:
             self.set_completer()
 
         if self.banner and header:
             format = '%s\n%s\n'
         else:
             format = '%s%s\n'
         banner =  format % (self.banner,header)
 
         # Call the embedding code with a stack depth of 1 so it can skip over
         # our call and get the original caller's namespaces.
-        self.embed_mainloop(banner, local_ns, global_ns, 
+        self.mainloop(banner, local_ns, global_ns, 
                             stack_depth=stack_depth)
 
         if self.exit_msg is not None:
             print self.exit_msg
             
         # Restore global systems (display, completion)
         self.restore_sys_displayhook()
         self.restore_sys_ipcompleter()
 
+    def mainloop(self,header='',local_ns=None,global_ns=None,stack_depth=0):
+        """Embeds IPython into a running python program.
+
+        Input:
+
+          - header: An optional header message can be specified.
+
+          - local_ns, global_ns: working namespaces. If given as None, the
+          IPython-initialized one is updated with __main__.__dict__, so that
+          program variables become visible but user-specific configuration
+          remains possible.
+
+          - stack_depth: specifies how many levels in the stack to go to
+          looking for namespaces (when local_ns and global_ns are None).  This
+          allows an intermediate caller to make sure that this function gets
+          the namespace from the intended level in the stack.  By default (0)
+          it will get its locals and globals from the immediate caller.
+
+        Warning: it's possible to use this in a program which is being run by
+        IPython itself (via %run), but some funny things will happen (a few
+        globals get overwritten). In the future this will be cleaned up, as
+        there is no fundamental reason why it can't work perfectly."""
+
+        # Get locals and globals from caller
+        if local_ns is None or global_ns is None:
+            call_frame = sys._getframe(stack_depth).f_back
+
+            if local_ns is None:
+                local_ns = call_frame.f_locals
+            if global_ns is None:
+                global_ns = call_frame.f_globals
+
+        # Update namespaces and fire up interpreter
+
+        # The global one is easy, we can just throw it in
+        self.user_global_ns = global_ns
+
+        # but the user/local one is tricky: ipython needs it to store internal
+        # data, but we also need the locals.  We'll copy locals in the user
+        # one, but will track what got copied so we can delete them at exit.
+        # This is so that a later embedded call doesn't see locals from a
+        # previous call (which most likely existed in a separate scope).
+        local_varnames = local_ns.keys()
+        self.user_ns.update(local_ns)
+        #self.user_ns['local_ns'] = local_ns  # dbg
+
+        # Patch for global embedding to make sure that things don't overwrite
+        # user globals accidentally. Thanks to Richard <[e-mail]>
+        # FIXME. Test this a bit more carefully (the if.. is new)
+        if local_ns is None and global_ns is None:
+            self.user_global_ns.update(__main__.__dict__)
+
+        # make sure the tab-completer has the correct frame information, so it
+        # actually completes using the frame's locals/globals
+        self.set_completer_frame()
+
+        with self.builtin_trap:
+            self.interact(header)
+        
+            # now, purge out the user namespace from anything we might have added
+            # from the caller's local namespace
+            delvar = self.user_ns.pop
+            for var in local_varnames:
+                delvar(var,None)
+
 
 _embedded_shell = None
 
 
 def embed(header='', config=None, usage=None, banner1=None, banner2=None,
           exit_msg=''):
     """Call this to embed IPython at the current point in your program.
 
     The first invocation of this will create an :class:`InteractiveShellEmbed`
     instance and then call it.  Consecutive calls just call the already
     created instance.
 
     Here is a simple example::
 
         from IPython import embed
         a = 10
         b = 20
         embed('First time')
         c = 30
         d = 40
         embed
 
     Full customization can be done by passing a :class:`Struct` in as the 
     config argument.
     """
     global _embedded_shell
     if _embedded_shell is None:
         _embedded_shell = InteractiveShellEmbed(config=config,
         usage=usage, banner1=banner1, banner2=banner2, exit_msg=exit_msg)
     _embedded_shell(header=header, stack_depth=2)
 

IPython/core/iplib.py

@@ -1,3100 +1,2962 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 __main__
 import __builtin__
 import StringIO
 import bdb
 import codeop
 import exceptions
 import glob
 import keyword
 import new
 import os
 import re
 import shutil
 import string
 import sys
 import tempfile
 
 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.autocall import IPyAutocall
+from IPython.core.builtin_trap import BuiltinTrap
 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.page import page
 from IPython.core.component import Component
 from IPython.core.oldusersetup import user_setup
 from IPython.core.usage import interactive_usage, default_banner
 from IPython.core.error import TryNext, UsageError
 
 from IPython.extensions 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.strdispatch import StrDispatch
 from IPython.utils.platutils import toggle_set_term_title, set_term_title
 
 from IPython.utils.traitlets import (
     Int, Float, 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 BuiltinUndefined: pass
-BuiltinUndefined = BuiltinUndefined()
-
-
-class Quitter(object):
-    """Simple class to handle exit, similar to Python 2.5's.
-
-    It handles exiting in an ipython-safe manner, which the one in Python 2.5
-    doesn't do (obviously, since it doesn't know about ipython)."""
-    
-    def __init__(self, shell, name):
-        self.shell = shell
-        self.name = name
-        
-    def __repr__(self):
-        return 'Type %s() to exit.' % self.name
-    __str__ = __repr__
-
-    def __call__(self):
-        self.shell.exit()
-
-
 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
 
 
 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), config_key='AUTOCALL')
     autoedit_syntax = CBool(False, config_key='AUTOEDIT_SYNTAX')
     autoindent = CBool(True, config_key='AUTOINDENT')
     automagic = CBool(True, config_key='AUTOMAGIC')
     display_banner = CBool(True, config_key='DISPLAY_BANNER')
     banner = Str('')
     banner1 = Str(default_banner, config_key='BANNER1')
     banner2 = Str('', config_key='BANNER2')
     c = Str('', config_key='C')
     cache_size = Int(1000, config_key='CACHE_SIZE')
     classic = CBool(False, config_key='CLASSIC')
     color_info = CBool(True, config_key='COLOR_INFO')
     colors = CaselessStrEnum(('NoColor','LightBG','Linux'), 
                              default_value='LightBG', config_key='COLORS')
     confirm_exit = CBool(True, config_key='CONFIRM_EXIT')
     debug = CBool(False, config_key='DEBUG')
     deep_reload = CBool(False, config_key='DEEP_RELOAD')
     embedded = CBool(False)
     embedded_active = CBool(False)
     editor = Str(get_default_editor(), config_key='EDITOR')
     filename = Str("<ipython console>")
     interactive = CBool(False, config_key='INTERACTIVE')
     ipythondir= Unicode('', config_key='IPYTHONDIR') # Set to os.getcwd() in __init__
     logstart = CBool(False, config_key='LOGSTART')
     logfile = Str('', config_key='LOGFILE')
     logplay = Str('', config_key='LOGPLAY')
     multi_line_specials = CBool(True, config_key='MULTI_LINE_SPECIALS')
     object_info_string_level = Enum((0,1,2), default_value=0,
                                     config_keys='OBJECT_INFO_STRING_LEVEL')
     pager = Str('less', config_key='PAGER')
     pdb = CBool(False, config_key='PDB')
     pprint = CBool(True, config_key='PPRINT')
     profile = Str('', config_key='PROFILE')
     prompt_in1 = Str('In [\\#]: ', config_key='PROMPT_IN1')
     prompt_in2 = Str('   .\\D.: ', config_key='PROMPT_IN2')
     prompt_out = Str('Out[\\#]: ', config_key='PROMPT_OUT1')
     prompts_pad_left = CBool(True, config_key='PROMPTS_PAD_LEFT')
     quiet = CBool(False, config_key='QUIET')
 
     readline_use = CBool(True, config_key='READLINE_USE')
     readline_merge_completions = CBool(True, 
                                        config_key='READLINE_MERGE_COMPLETIONS')
     readline_omit__names = Enum((0,1,2), default_value=0, 
                                 config_key='READLINE_OMIT_NAMES')
     readline_remove_delims = Str('-/~', config_key='READLINE_REMOVE_DELIMS')
     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_key='READLINE_PARSE_AND_BIND'
     )
 
     screen_length = Int(0, config_key='SCREEN_LENGTH')
     
     # Use custom TraitletTypes that convert '0'->'' and '\\n'->'\n'
     separate_in = SeparateStr('\n', config_key='SEPARATE_IN')
     separate_out = SeparateStr('', config_key='SEPARATE_OUT')
     separate_out2 = SeparateStr('', config_key='SEPARATE_OUT2')
 
     system_header = Str('IPython system call: ', config_key='SYSTEM_HEADER')
     system_verbose = CBool(False, config_key='SYSTEM_VERBOSE')
     term_title = CBool(False, config_key='TERM_TITLE')
     wildcards_case_sensitive = CBool(True, config_key='WILDCARDS_CASE_SENSITIVE')
     xmode = CaselessStrEnum(('Context','Plain', 'Verbose'), 
                             default_value='Context', config_key='XMODE')
 
     alias = List(allow_none=False, config_key='ALIAS')
     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,
                  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, name='__IP')
 
         # 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)
 
         # Create namespaces (user_ns, user_global_ns, alias_table, 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_handlers()
 
         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_aliases()
         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 cleanup(self):
-        self.remove_builtins()
         self.restore_sys_module_state()
 
     #-------------------------------------------------------------------------
     # Traitlet changed handlers
     #-------------------------------------------------------------------------
 
     def _banner1_changed(self):
         self.compute_banner()
 
     def _banner2_changed(self):
         self.compute_banner()
 
     @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()
 
     #-------------------------------------------------------------------------
     # init_* methods called by __init__
     #-------------------------------------------------------------------------
 
     def init_ipythondir(self, ipythondir):
         if ipythondir is not None:
             self.ipythondir = ipythondir
             self.config.IPYTHONDIR = self.ipythondir
             return
 
         if hasattr(self.config, 'IPYTHONDIR'):
             self.ipythondir = self.config.IPYTHONDIR
         if not hasattr(self.config, 'IPYTHONDIR'):
             # cdw is always defined
             self.ipythondir = os.getcwd()
 
         # The caller must make sure that ipythondir exists.  We should
         # probably handle this using a Dir traitlet.
         if not os.path.isdir(self.ipythondir):
             raise IOError('IPython dir does not exist: %s' % self.ipythondir)
 
         # All children can just read this
         self.config.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_banner(self, banner1, banner2):
         if self.c:  # regular python doesn't print the banner with -c
             self.display_banner = False
         if banner1 is not None:
             self.banner1 = banner1
         if banner2 is not None:
             self.banner2 = banner2
         self.compute_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'        
 
     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 = {}
 
         # Namespace of system aliases.  Each entry in the alias
         # table must be a 2-tuple of the form (N,name), where N is the number
         # of positional arguments of the alias.
         self.alias_table = {}
 
         # 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,
                          'alias':self.alias_table,
                          '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.alias_table, 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_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
         try:
             histfname = 'history-%s' % self.profile
         except AttributeError:
             histfname = 'history'
         self.histfile = os.path.join(self.config.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_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_handlers(self):
         # escapes for automatic behavior on the command line
         self.ESC_SHELL  = '!'
         self.ESC_SH_CAP = '!!'
         self.ESC_HELP   = '?'
         self.ESC_MAGIC  = '%'
         self.ESC_QUOTE  = ','
         self.ESC_QUOTE2 = ';'
         self.ESC_PAREN  = '/'
 
         # And their associated handlers
         self.esc_handlers = {self.ESC_PAREN  : self.handle_auto,
                              self.ESC_QUOTE  : self.handle_auto,
                              self.ESC_QUOTE2 : self.handle_auto,
                              self.ESC_MAGIC  : self.handle_magic,
                              self.ESC_HELP   : self.handle_help,
                              self.ESC_SHELL  : self.handle_shell_escape,
                              self.ESC_SH_CAP : self.handle_shell_escape,
                              }
 
     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_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 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_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 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
         # template for logfile headers.  It gets resolved at runtime by the
         # logstart method.
         self.loghead_tpl = \
 """#log# Automatic Logger file. *** THIS MUST BE THE FIRST LINE ***
 #log# DO NOT CHANGE THIS LINE OR THE TWO BELOW
 #log# opts = %s
 #log# args = %s
 #log# It is safe to make manual edits below here.
 #log#-----------------------------------------------------------------------
 """
 
     def init_logstart(self):
         if self.logplay:
             self.magic_logstart(self.logplay + ' append')
         elif  self.logfile:
             self.magic_logstart(self.logfile)
         elif self.logstart:
             self.magic_logstart()
 
     def init_aliases(self):
         # dict of things NOT to alias (keywords, builtins and some magics)
         no_alias = {}
         no_alias_magics = ['cd','popd','pushd','dhist','alias','unalias']
         for key in keyword.kwlist + no_alias_magics:
             no_alias[key] = 1
         no_alias.update(__builtin__.__dict__)
         self.no_alias = no_alias
 
         # Make some aliases automatically
         # Prepare list of shell aliases to auto-define
         if os.name == 'posix':
             auto_alias = ('mkdir mkdir', 'rmdir rmdir',
                           'mv mv -i','rm rm -i','cp cp -i',
                           'cat cat','less less','clear clear',
                           # a better ls
                           'ls ls -F',
                           # long ls
                           'll ls -lF')
             # Extra ls aliases with color, which need special treatment on BSD
             # variants
             ls_extra = ( # color ls
                          'lc ls -F -o --color',
                          # ls normal files only
                          'lf ls -F -o --color %l | grep ^-',
                          # ls symbolic links
                          'lk ls -F -o --color %l | grep ^l',
                          # directories or links to directories,
                          'ldir ls -F -o --color %l | grep /$',
                          # things which are executable
                          'lx ls -F -o --color %l | grep ^-..x',
                          )
             # The BSDs don't ship GNU ls, so they don't understand the
             # --color switch out of the box
             if 'bsd' in sys.platform:
                 ls_extra = ( # ls normal files only
                              'lf ls -lF | grep ^-',
                              # ls symbolic links
                              'lk ls -lF | grep ^l',
                              # directories or links to directories,
                              'ldir ls -lF | grep /$',
                              # things which are executable
                              'lx ls -lF | grep ^-..x',
                              )
             auto_alias = auto_alias + ls_extra
         elif os.name in ['nt','dos']:
             auto_alias = ('ls dir /on',
                           'ddir dir /ad /on', 'ldir dir /ad /on',
                           'mkdir mkdir','rmdir rmdir','echo echo',
                           'ren ren','cls cls','copy copy')
         else:
             auto_alias = ()
         self.auto_alias = [s.split(None,1) for s in auto_alias]
         
         # Load default aliases
         for alias, cmd in self.auto_alias:
             self.define_alias(alias,cmd)
 
         # Load user aliases
         for alias in self.alias:
             self.magic_alias(alias)
 
     def init_builtins(self):
-        # track which builtins we add, so we can clean up later
-        self._orig_builtins = {}
-        self._builtins_added = False
-        self.add_builtins()
+        self.builtin_trap = BuiltinTrap(self)
 
     def init_shadow_hist(self):
         try:
             self.db = pickleshare.PickleShareDB(self.config.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.config.IPYTHONDIR
             sys.exit()
         self.shadowhist = ipcorehist.ShadowHist(self.db)
 
     def init_inspector(self):
         # Object inspector
         self.inspector = oinspect.Inspector(oinspect.InspectColors,
                                             PyColorize.ANSICodeColors,
                                             'NoColor',
                                             self.object_info_string_level)
 
     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_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 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):
         # I don't like assigning globally to sys, because it means when
         # embedding instances, each embedded instance overrides the previous
         # choice. But sys.displayhook seems to be called internally by exec,
         # so I don't see a way around it.  We first save the original and then
         # overwrite it.
         self.sys_displayhook = sys.displayhook
         sys.displayhook = 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.")
 
     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 init_pdb(self):
         # Set calling of pdb on exceptions
         # self.call_pdb is a property
         self.call_pdb = self.pdb
 
     # def init_exec_commands(self):
     #     for cmd in self.config.EXECUTE:
     #         print "execute:", cmd
     #         self.api.runlines(cmd)
     #         
     #     batchrun = False
     #     if self.config.has_key('EXECFILE'):
     #         for batchfile in [path(arg) for arg in self.config.EXECFILE
     #             if arg.lower().endswith('.ipy')]:
     #             if not batchfile.isfile():
     #                 print "No such batch file:", batchfile
     #                 continue
     #             self.api.runlines(batchfile.text())
     #             batchrun = True
     #     # without -i option, exit after running the batch file
     #     if batchrun and not self.interactive:
     #         self.ask_exit()            
 
     # def load(self, mod):
     #     """ Load an extension.
     #     
     #     Some modules should (or must) be 'load()':ed, rather than just imported.
     #     
     #     Loading will do:
     #     
     #     - run init_ipython(ip)
     #     - run ipython_firstrun(ip)
     #     """
     # 
     #     if mod in self.extensions:
     #         # just to make sure we don't init it twice
     #         # note that if you 'load' a module that has already been
     #         # imported, init_ipython gets run anyway
     #         
     #         return self.extensions[mod]
     #     __import__(mod)
     #     m = sys.modules[mod]
     #     if hasattr(m,'init_ipython'):
     #         m.init_ipython(self)
     #         
     #     if hasattr(m,'ipython_firstrun'):
     #         already_loaded = self.db.get('firstrun_done', set())
     #         if mod not in already_loaded:
     #             m.ipython_firstrun(self)
     #             already_loaded.add(mod)
     #             self.db['firstrun_done'] = already_loaded
     #         
     #     self.extensions[mod] = m
     #     return m
 
     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.
         """
         # The user namespace MUST have a pointer to the shell itself.
         self.user_ns[self.name] = self
 
         # Store myself as the public api!!!
         self.user_ns['_ip'] = self
 
         # 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 add_builtin(self, key, value):
-        """Add a builtin and save the original."""
-        orig = __builtin__.__dict__.get(key, BuiltinUndefined)
-        self._orig_builtins[key] = orig
-        __builtin__.__dict__[key] = value
-
-    def remove_builtin(self, key):
-        """Remove an added builtin and re-set the original."""
-        try:
-            orig = self._orig_builtins.pop(key)
-        except KeyError:
-            pass
-        else:
-            if orig is BuiltinUndefined:
-                del __builtin__.__dict__[key]
-            else:
-                __builtin__.__dict__[key] = orig
-
-    def add_builtins(self):
-        """Store ipython references into the __builtin__ namespace.
-
-        We strive to modify the __builtin__ namespace as little as possible.
-        """
-        if not self._builtins_added:
-            self.add_builtin('exit', Quitter(self,'exit'))
-            self.add_builtin('quit', Quitter(self,'quit'))
-
-            # Recursive reload function
-            try:
-                from IPython.lib import deepreload
-                if self.deep_reload:
-                    self.add_builtin('reload', deepreload.reload)
-                else:
-                    self.add_builtin('dreload', deepreload.reload)
-                del deepreload
-            except ImportError:
-                pass
-
-            # Keep in the builtins a flag for when IPython is active.  We set it
-            # with setdefault so that multiple nested IPythons don't clobber one
-            # another.  Each will increase its value by one upon being activated,
-            # which also gives us a way to determine the nesting level.
-            __builtin__.__dict__.setdefault('__IPYTHON__active',0)
-            self._builtins_added = True
-
-    def remove_builtins(self):
-        """Remove any builtins which might have been added by add_builtins, or
-        restore overwritten ones to their previous values."""
-        if self._builtins_added:
-            for key in self._orig_builtins.keys():
-                self.remove_builtin(key)
-            self._orig_builtins.clear()
-            self._builtins_added = False
-
     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['displayhook'] = sys.displayhook
         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
 
     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)
 
     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 set_custom_completer(self,completer,pos=0):
         """set_custom_completer(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 _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 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(self.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)
-            return fn(magic_args)
+            with 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
 
     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
 
     def define_alias(self, name, cmd):
         """ Define a new alias."""
 
         if callable(cmd):
             self.alias_table[name] = cmd
             from IPython.core import shadowns
             setattr(shadowns, name, cmd)
             return
 
         if isinstance(cmd, basestring):
             nargs = cmd.count('%s')
             if nargs>0 and cmd.find('%l')>=0:
                 raise Exception('The %s and %l specifiers are mutually '
                                 'exclusive in alias definitions.')
                   
             self.alias_table[name] = (nargs,cmd)
             return
         
         self.alias_table[name] = cmd
 
     def ipalias(self,arg_s):
         """Call an alias by name.
 
         Input: a string containing the name of the alias to call and any
         additional arguments to be passed to the magic.
 
         ipalias('name -opt foo bar') is equivalent to typing at the ipython
         prompt:
 
         In[1]: name -opt foo bar
 
         To call an alias without arguments, simply use ipalias('name').
 
         This provides a proper Python function to call IPython's aliases in any
         valid Python code you can type at the interpreter, including loops and
         compound statements.  It is added by IPython to the Python builtin
         namespace upon initialization."""
 
         args = arg_s.split(' ',1)
         alias_name = args[0]
         try:
             alias_args = args[1]
         except IndexError:
             alias_args = ''
         if alias_name in self.alias_table:
             self.call_alias(alias_name,alias_args)
         else:
             error("Alias `%s` not found." % alias_name)
 
     def system(self, cmd):
         """Make a system call, using IPython."""
         return self.hooks.shell_hook(self.var_expand(cmd, depth=2))
 
     def ex(self, cmd):
         """Execute a normal python statement in user namespace."""
+        with 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
         """
-        return eval(expr, self.user_global_ns, self.user_ns)
+        with self.builtin_trap:
+            result = eval(expr, self.user_global_ns, self.user_ns)
+        return result
 
     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 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_completer_frame(self, frame=None):
         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
 
     def init_auto_alias(self):
         """Define some aliases automatically.
 
         These are ALL parameter-less aliases"""
 
         for alias,cmd in self.auto_alias:
             self.define_alias(alias,cmd)
 
     def alias_table_validate(self,verbose=0):
         """Update information about the alias table.
 
         In particular, make sure no Python keywords/builtins are in it."""
 
         no_alias = self.no_alias
         for k in self.alias_table.keys():
             if k in no_alias:
                 del self.alias_table[k]
                 if verbose:
                     print ("Deleting alias <%s>, it's a Python "
                            "keyword or builtin." % k)
 
     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 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
 
     def atexit_operations(self):
         """This will be executed at the time of exit.
 
         Saving of persistent data should be performed here. """
 
         #print '*** IPython exit cleanup ***' # dbg
         # input history
         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 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()
 
         # 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()
         
     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
             
     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 ask_yes_no(self,prompt,default=True):
         if self.quiet:
             return True
         return ask_yes_no(prompt,default)
 
     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()
 
     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
         
     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:
                         sys.displayhook(f.read())
                     finally:
                         f.close()
                 except:
                     self.showtraceback()
 
     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 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)()
 
     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 mainloop(self, banner=None):
         """Start the mainloop.
 
         If an optional banner argument is given, it will override the
         internally created default banner.
         """
+        
+        with self.builtin_trap:
         if self.c:  # Emulate Python's -c option
             self.exec_init_cmd()
 
         if self.display_banner:
             if banner is None:
                 banner = self.banner
 
         # 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()
                 #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 exec_init_cmd(self):
         """Execute a command given at the command line.
 
         This emulates Python's -c option."""
 
         #sys.argv = ['-c']
         self.push_line(self.prefilter(self.c, False))
         if not self.interactive:
             self.ask_exit()
 
-    def embed_mainloop(self,header='',local_ns=None,global_ns=None,stack_depth=0):
-        """Embeds IPython into a running python program.
-
-        Input:
-
-          - header: An optional header message can be specified.
-
-          - local_ns, global_ns: working namespaces. If given as None, the
-          IPython-initialized one is updated with __main__.__dict__, so that
-          program variables become visible but user-specific configuration
-          remains possible.
-
-          - stack_depth: specifies how many levels in the stack to go to
-          looking for namespaces (when local_ns and global_ns are None).  This
-          allows an intermediate caller to make sure that this function gets
-          the namespace from the intended level in the stack.  By default (0)
-          it will get its locals and globals from the immediate caller.
-
-        Warning: it's possible to use this in a program which is being run by
-        IPython itself (via %run), but some funny things will happen (a few
-        globals get overwritten). In the future this will be cleaned up, as
-        there is no fundamental reason why it can't work perfectly."""
-
-        # Get locals and globals from caller
-        if local_ns is None or global_ns is None:
-            call_frame = sys._getframe(stack_depth).f_back
-
-            if local_ns is None:
-                local_ns = call_frame.f_locals
-            if global_ns is None:
-                global_ns = call_frame.f_globals
-
-        # Update namespaces and fire up interpreter
-
-        # The global one is easy, we can just throw it in
-        self.user_global_ns = global_ns
-
-        # but the user/local one is tricky: ipython needs it to store internal
-        # data, but we also need the locals.  We'll copy locals in the user
-        # one, but will track what got copied so we can delete them at exit.
-        # This is so that a later embedded call doesn't see locals from a
-        # previous call (which most likely existed in a separate scope).
-        local_varnames = local_ns.keys()
-        self.user_ns.update(local_ns)
-        #self.user_ns['local_ns'] = local_ns  # dbg
-
-        # Patch for global embedding to make sure that things don't overwrite
-        # user globals accidentally. Thanks to Richard <[e-mail]>
-        # FIXME. Test this a bit more carefully (the if.. is new)
-        if local_ns is None and global_ns is None:
-            self.user_global_ns.update(__main__.__dict__)
-
-        # make sure the tab-completer has the correct frame information, so it
-        # actually completes using the frame's locals/globals
-        self.set_completer_frame()
-
-        # before activating the interactive mode, we need to make sure that
-        # all names in the builtin namespace needed by ipython point to
-        # ourselves, and not to other instances.
-        self.add_builtins()
-
-        self.interact(header)
-        
-        # now, purge out the user namespace from anything we might have added
-        # from the caller's local namespace
-        delvar = self.user_ns.pop
-        for var in local_varnames:
-            delvar(var,None)
-        # and clean builtins we may have overridden
-        self.remove_builtins()
-
     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(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, banner=None):
         """Closely emulate the interactive Python console."""
 
         # batch run -> do not interact        
         if self.exit_now:
             return
 
         if self.display_banner:
             if banner is None:
                 banner = self.banner
             self.write(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 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 expand_alias(self, line):
         """ Expand an alias in the command line 
         
         Returns the provided command line, possibly with the first word 
         (command) translated according to alias expansion rules.
         
         [ipython]|16> _ip.expand_aliases("np myfile.txt")
                  <16> 'q:/opt/np/notepad++.exe myfile.txt'
         """
         
         pre,fn,rest = self.split_user_input(line)
         res = pre + self.expand_aliases(fn, rest)
         return res
 
     def expand_aliases(self, fn, rest):
         """Expand multiple levels of aliases:
         
         if:
         
         alias foo bar /tmp
         alias baz foo
         
         then:
         
         baz huhhahhei -> bar /tmp huhhahhei
         
         """
         line = fn + " " + rest
         
         done = set()
         while 1:
             pre,fn,rest = prefilter.splitUserInput(line,
                                                    prefilter.shell_line_split)
             if fn in self.alias_table:
                 if fn in done:
                     warn("Cyclic alias definition, repeated '%s'" % fn)
                     return ""
                 done.add(fn)
 
                 l2 = self.transform_alias(fn,rest)
                 # dir -> dir 
                 # print "alias",line, "->",l2  #dbg
                 if l2 == line:
                     break
                 # ls -> ls -F should not recurse forever
                 if l2.split(None,1)[0] == line.split(None,1)[0]:
                     line = l2
                     break
                 
                 line=l2
                 
                 
                 # print "al expand to",line #dbg
             else:
                 break
                 
         return line
 
     def transform_alias(self, alias,rest=''):
         """ Transform alias to system command string.
         """
         trg = self.alias_table[alias]
 
         nargs,cmd = trg
         # print trg #dbg
         if ' ' in cmd and os.path.isfile(cmd):
             cmd = '"%s"' % cmd
 
         # Expand the %l special to be the user's input line
         if cmd.find('%l') >= 0:
             cmd = cmd.replace('%l',rest)
             rest = ''
         if nargs==0:
             # Simple, argument-less aliases
             cmd = '%s %s' % (cmd,rest)
         else:
             # Handle aliases with positional arguments
             args = rest.split(None,nargs)
             if len(args)< nargs:
                 error('Alias <%s> requires %s arguments, %s given.' %
                       (alias,nargs,len(args)))
                 return None
             cmd = '%s %s' % (cmd % tuple(args[:nargs]),' '.join(args[nargs:]))
         # Now call the macro, evaluating in the user's namespace
         #print 'new command: <%r>' % cmd  # dbg
         return cmd
         
     def call_alias(self,alias,rest=''):
         """Call an alias given its name and the rest of the line.
 
         This is only used to provide backwards compatibility for users of
         ipalias(), use of which is not recommended for anymore."""
 
         # Now call the macro, evaluating in the user's namespace
         cmd = self.transform_alias(alias, rest)
         try:
             self.system(cmd)
         except:
             self.showtraceback()
 
     def indent_current_str(self):
         """return the current level of indentation as a string"""
         return self.indent_current_nsp * ' '
 
     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 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
 
     def cleanup_ipy_script(self, script):
         """Make a script safe for self.runlines()
 
         Notes
         -----
         This was copied over from the old ipapi and probably can be done
         away with once we move to block based interpreter.
         
         - Removes empty lines Suffixes all indented blocks that end with
         - unindented lines with empty lines
         """
         
         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)
             def is_secondary_block_start(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
                     
             if level > 0 and newlevel == 0 and \
                    not 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 self.builtin_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")
                 more = self.push_line(self.prefilter(line,more))
                 # 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 split_user_input(self, line):
         # This is really a hold-over to support ipapi and some extensions
         return prefilter.splitUserInput(line)
 
     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.
         """
 
         # 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 some config option is set?
                     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(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
 
     def _prefilter(self, line, continue_prompt):
         """Calls different preprocessors, depending on the form of line."""
 
         # All handlers *must* return a value, even if it's blank ('').
 
         # Lines are NOT logged here. Handlers should process the line as
         # needed, update the cache AND log it (so that the input cache array
         # stays synced).
 
         #.....................................................................
         # Code begins
 
         #if line.startswith('%crash'): raise RuntimeError,'Crash now!'  # dbg
 
         # save the line away in case we crash, so the post-mortem handler can
         # record it
         self._last_input_line = line
 
         #print '***line: <%s>' % line # dbg
 
         if not line:
             # Return immediately on purely empty lines, so that if the user
             # previously typed some whitespace that started a continuation
             # prompt, he can break out of that loop with just an empty line.
             # This is how the default python prompt works.
 
             # Only return if the accumulated input buffer was just whitespace!
             if ''.join(self.buffer).isspace():
                 self.buffer[:] = []
             return ''
         
         line_info = prefilter.LineInfo(line, continue_prompt)
         
         # the input history needs to track even empty lines
         stripped = line.strip()
         
         if not stripped:
             if not continue_prompt:
                 self.outputcache.prompt_count -= 1
             return self.handle_normal(line_info)
 
         # print '***cont',continue_prompt  # dbg
         # special handlers are only allowed for single line statements
         if continue_prompt and not self.multi_line_specials:
             return self.handle_normal(line_info)
 
 
         # See whether any pre-existing handler can take care of it  
         rewritten = self.hooks.input_prefilter(stripped)
         if rewritten != stripped: # ok, some prefilter did something
             rewritten = line_info.pre + rewritten  # add indentation
             return self.handle_normal(prefilter.LineInfo(rewritten,
                                                          continue_prompt))
             
         #print 'pre <%s> iFun <%s> rest <%s>' % (pre,iFun,theRest)  # dbg
         
         return prefilter.prefilter(line_info, self)
 
 
     def _prefilter_dumb(self, line, continue_prompt):
         """simple prefilter function, for debugging"""
         return self.handle_normal(line,continue_prompt)
 
     
     def multiline_prefilter(self, line, continue_prompt):
         """ Run _prefilter for each line of input
         
         Covers cases where there are multiple lines in the user entry,
         which is the case when the user goes back to a multiline history
         entry and presses enter.
         
         """
         out = []
         for l in line.rstrip('\n').split('\n'):
             out.append(self._prefilter(l, continue_prompt))
         return '\n'.join(out)
     
     # Set the default prefilter() function (this can be user-overridden)
     prefilter = multiline_prefilter
 
     def handle_normal(self,line_info):
         """Handle normal input lines. Use as a template for handlers."""
 
         # With autoindent on, we need some way to exit the input loop, and I
         # don't want to force the user to have to backspace all the way to
         # clear the line.  The rule will be in this case, that either two
         # lines of pure whitespace in a row, or a line of pure whitespace but
         # of a size different to the indent level, will exit the input loop.
         line = line_info.line
         continue_prompt = line_info.continue_prompt
         
         if (continue_prompt and self.autoindent and line.isspace() and
             (0 < abs(len(line) - self.indent_current_nsp) <= 2 or
              (self.buffer[-1]).isspace() )):
             line = ''
 
         self.log(line,line,continue_prompt)
         return line
 
     def handle_alias(self,line_info):
         """Handle alias input lines. """
         tgt = self.alias_table[line_info.iFun]
         # print "=>",tgt #dbg
         if callable(tgt):
             if '$' in line_info.line:
                 call_meth = '(_ip, _ip.var_expand(%s))'
             else:
                 call_meth = '(_ip,%s)'
             line_out = ("%s_sh.%s" + call_meth) % (line_info.preWhitespace,
                                          line_info.iFun, 
             make_quoted_expr(line_info.line))
         else:
             transformed = self.expand_aliases(line_info.iFun,line_info.theRest)
 
             # pre is needed, because it carries the leading whitespace.  Otherwise
             # aliases won't work in indented sections.
             line_out = '%s_ip.system(%s)' % (line_info.preWhitespace,
                                              make_quoted_expr( transformed ))
         
         self.log(line_info.line,line_out,line_info.continue_prompt)
         #print 'line out:',line_out # dbg
         return line_out
 
     def handle_shell_escape(self, line_info):
         """Execute the line in a shell, empty return value"""
         #print 'line in :', `line` # dbg
         line = line_info.line
         if line.lstrip().startswith('!!'):
             # rewrite LineInfo's line, iFun and theRest to properly hold the
             # call to %sx and the actual command to be executed, so
             # handle_magic can work correctly.  Note that this works even if
             # the line is indented, so it handles multi_line_specials
             # properly.
             new_rest = line.lstrip()[2:]
             line_info.line = '%ssx %s' % (self.ESC_MAGIC,new_rest)
             line_info.iFun = 'sx'
             line_info.theRest = new_rest
             return self.handle_magic(line_info)
         else:
             cmd = line.lstrip().lstrip('!')
             line_out = '%s_ip.system(%s)' % (line_info.preWhitespace,
                                              make_quoted_expr(cmd))
         # update cache/log and return
         self.log(line,line_out,line_info.continue_prompt)
         return line_out
 
     def handle_magic(self, line_info):
         """Execute magic functions."""
         iFun    = line_info.iFun
         theRest = line_info.theRest
         cmd = '%s_ip.magic(%s)' % (line_info.preWhitespace,
                                    make_quoted_expr(iFun + " " + theRest))
         self.log(line_info.line,cmd,line_info.continue_prompt)
         #print 'in handle_magic, cmd=<%s>' % cmd  # dbg
         return cmd
 
     def handle_auto(self, line_info):
         """Hande lines which can be auto-executed, quoting if requested."""
 
         line    = line_info.line
         iFun    = line_info.iFun
         theRest = line_info.theRest
         pre     = line_info.pre
         continue_prompt = line_info.continue_prompt
         obj = line_info.ofind(self)['obj']
 
         #print 'pre <%s> iFun <%s> rest <%s>' % (pre,iFun,theRest)  # dbg
 
         # This should only be active for single-line input!
         if continue_prompt:
             self.log(line,line,continue_prompt)
             return line
 
         force_auto = isinstance(obj, IPyAutocall)
         auto_rewrite = True
         
         if pre == self.ESC_QUOTE:
             # Auto-quote splitting on whitespace
             newcmd = '%s("%s")' % (iFun,'", "'.join(theRest.split()) )
         elif pre == self.ESC_QUOTE2:
             # Auto-quote whole string
             newcmd = '%s("%s")' % (iFun,theRest)
         elif pre == self.ESC_PAREN:
             newcmd = '%s(%s)' % (iFun,",".join(theRest.split()))
         else:
             # Auto-paren.
             # We only apply it to argument-less calls if the autocall
             # parameter is set to 2.  We only need to check that autocall is <
             # 2, since this function isn't called unless it's at least 1.
             if not theRest and (self.autocall < 2) and not force_auto:
                 newcmd = '%s %s' % (iFun,theRest)
                 auto_rewrite = False
             else:
                 if not force_auto and theRest.startswith('['):
                     if hasattr(obj,'__getitem__'):
                         # Don't autocall in this case: item access for an object
                         # which is BOTH callable and implements __getitem__.
                         newcmd = '%s %s' % (iFun,theRest)
                         auto_rewrite = False
                     else:
                         # if the object doesn't support [] access, go ahead and
                         # autocall
                         newcmd = '%s(%s)' % (iFun.rstrip(),theRest)
                 elif theRest.endswith(';'):
                     newcmd = '%s(%s);' % (iFun.rstrip(),theRest[:-1])
                 else:
                     newcmd = '%s(%s)' % (iFun.rstrip(), theRest)
 
         if auto_rewrite:
             rw = self.outputcache.prompt1.auto_rewrite() + newcmd
             
             try:
                 # plain ascii works better w/ pyreadline, on some machines, so
                 # we use it and only print uncolored rewrite if we have unicode
                 rw = str(rw)
                 print >>Term.cout, rw
             except UnicodeEncodeError:
                 print "-------------->" + newcmd
             
         # log what is now valid Python, not the actual user input (without the
         # final newline)
         self.log(line,newcmd,continue_prompt)
         return newcmd
 
     def handle_help(self, line_info):
         """Try to get some help for the object.
 
         obj? or ?obj   -> basic information.
         obj?? or ??obj -> more details.
         """
         
         line = line_info.line
         # We need to make sure that we don't process lines which would be
         # otherwise valid python, such as "x=1 # what?"
         try:
             codeop.compile_command(line)
         except SyntaxError:
             # We should only handle as help stuff which is NOT valid syntax
             if line[0]==self.ESC_HELP:
                 line = line[1:]
             elif line[-1]==self.ESC_HELP:
                 line = line[:-1]
             self.log(line,'#?'+line,line_info.continue_prompt)
             if line:
                 #print 'line:<%r>' % line  # dbg
                 self.magic_pinfo(line)
             else:
                 page(self.usage,screen_lines=self.usable_screen_length)
             return '' # Empty string is needed here!
         except:
             # Pass any other exceptions through to the normal handler
             return self.handle_normal(line_info)
         else:
             # If the code compiles ok, we should handle it normally
             return self.handle_normal(line_info)
 
     def handle_emacs(self, line_info):
         """Handle input lines marked by python-mode."""
 
         # Currently, nothing is done.  Later more functionality can be added
         # here if needed.
 
         # The input cache shouldn't be updated
         return line_info.line
     
     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_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 safe_execfile(self,fname,*where,**kw):
         """A safe version of the builtin execfile().
 
         This version will never throw an exception, and knows how to handle
         ipython logs as well.
 
         :Parameters:
           fname : string
             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.
 
         :Keywords:
           islog : boolean (False)
 
           quiet : boolean (True)
 
           exit_ignore : boolean (False)
           """
 
         def syspath_cleanup():
             """Internal cleanup routine for sys.path."""
             if add_dname:
                 try:
                     sys.path.remove(dname)
                 except ValueError:
                     # For some reason the user has already removed it, ignore.
                     pass
         
         fname = os.path.expanduser(fname)
 
         # 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(os.path.abspath(fname))
         add_dname = False
         if dname not in sys.path:
             sys.path.insert(0,dname)
             add_dname = True
 
         try:
             xfile = open(fname)
         except:
             print >> Term.cerr, \
                   'Could not open file <%s> for safe execution.' % fname
             syspath_cleanup()
             return None
 
         kw.setdefault('islog',0)
         kw.setdefault('quiet',1)
         kw.setdefault('exit_ignore',0)
         
         first = xfile.readline()
         loghead = str(self.loghead_tpl).split('\n',1)[0].strip()
         xfile.close()
         # line by line execution
         if first.startswith(loghead) or kw['islog']:
             print 'Loading log file <%s> one line at a time...' % fname
             if kw['quiet']:
                 stdout_save = sys.stdout
                 sys.stdout = StringIO.StringIO()
             try:
                 globs,locs = where[0:2]
             except:
                 try:
                     globs = locs = where[0]
                 except:
                     globs = locs = globals()
             badblocks = []
 
             # we also need to identify indented blocks of code when replaying
             # logs and put them together before passing them to an exec
             # statement. This takes a bit of regexp and look-ahead work in the
             # file. It's easiest if we swallow the whole thing in memory
             # first, and manually walk through the lines list moving the
             # counter ourselves.
             indent_re = re.compile('\s+\S')
             xfile = open(fname)
             filelines = xfile.readlines()
             xfile.close()
             nlines = len(filelines)
             lnum = 0
             while lnum < nlines:
                 line = filelines[lnum]
                 lnum += 1
                 # don't re-insert logger status info into cache
                 if line.startswith('#log#'):
                     continue
                 else:
                     # build a block of code (maybe a single line) for execution
                     block = line
                     try:
                         next = filelines[lnum] # lnum has already incremented
                     except:
                         next = None
                     while next and indent_re.match(next):
                         block += next
                         lnum += 1
                         try:
                             next = filelines[lnum]
                         except:
                             next = None
                     # now execute the block of one or more lines
                     try:
                         exec block in globs,locs
                     except SystemExit:
                         pass
                     except:
                         badblocks.append(block.rstrip())
             if kw['quiet']:  # restore stdout
                 sys.stdout.close()
                 sys.stdout = stdout_save
             print 'Finished replaying log file <%s>' % fname
             if badblocks:
                 print >> sys.stderr, ('\nThe following lines/blocks in file '
                                       '<%s> reported errors:' % fname)
                     
                 for badline in badblocks:
                     print >> sys.stderr, badline
         else:  # regular file execution
             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 sys.version_info[:2] > (2,5):
                     if status.message!=0 and not kw['exit_ignore']:
                         show = True
                 else:
                     if status.code 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)
 
         syspath_cleanup()
 
 #************************* end of file <iplib.py> *****************************