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Subclass exit autocallable for two process shells, with argument to keep kernel alive.
Subclass exit autocallable for two process shells, with argument to keep kernel alive.

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builtin_trap.py
128 lines | 4.4 KiB | text/x-python | PythonLexer
"""
A context manager for managing things injected into :mod:`__builtin__`.
Authors:
* Brian Granger
* Fernando Perez
"""
#-----------------------------------------------------------------------------
# Copyright (C) 2010 The IPython Development Team.
#
# Distributed under the terms of the BSD License.
#
# Complete license in the file COPYING.txt, distributed with this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
import __builtin__
from IPython.config.configurable import Configurable
from IPython.utils.traitlets import Instance
#-----------------------------------------------------------------------------
# Classes and functions
#-----------------------------------------------------------------------------
class __BuiltinUndefined(object): pass
BuiltinUndefined = __BuiltinUndefined()
class __HideBuiltin(object): pass
HideBuiltin = __HideBuiltin()
class BuiltinTrap(Configurable):
shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
def __init__(self, shell=None):
super(BuiltinTrap, self).__init__(shell=shell, config=None)
self._orig_builtins = {}
# We define this to track if a single BuiltinTrap is nested.
# Only turn off the trap when the outermost call to __exit__ is made.
self._nested_level = 0
self.shell = shell
# builtins we always add - if set to HideBuiltin, they will just
# be removed instead of being replaced by something else
self.auto_builtins = {'exit': HideBuiltin,
'quit': HideBuiltin,
'get_ipython': self.shell.get_ipython,
}
# Recursive reload function
try:
from IPython.lib import deepreload
if self.shell.deep_reload:
self.auto_builtins['reload'] = deepreload.reload
else:
self.auto_builtins['dreload']= deepreload.reload
except ImportError:
pass
def __enter__(self):
if self._nested_level == 0:
self.activate()
self._nested_level += 1
# I return self, so callers can use add_builtin in a with clause.
return self
def __exit__(self, type, value, traceback):
if self._nested_level == 1:
self.deactivate()
self._nested_level -= 1
# Returning False will cause exceptions to propagate
return False
def add_builtin(self, key, value):
"""Add a builtin and save the original."""
bdict = __builtin__.__dict__
orig = bdict.get(key, BuiltinUndefined)
if value is HideBuiltin:
if orig is not BuiltinUndefined: #same as 'key in bdict'
self._orig_builtins[key] = orig
del bdict[key]
else:
self._orig_builtins[key] = orig
bdict[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 activate(self):
"""Store ipython references in the __builtin__ namespace."""
add_builtin = self.add_builtin
for name, func in self.auto_builtins.iteritems():
add_builtin(name, func)
# 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.
__builtin__.__dict__.setdefault('__IPYTHON__active', 0)
def deactivate(self):
"""Remove any builtins which might have been added by add_builtins, or
restore overwritten ones to their previous values."""
# Note: must iterate over a static keys() list because we'll be
# mutating the dict itself
remove_builtin = self.remove_builtin
for key in self._orig_builtins.keys():
remove_builtin(key)
self._orig_builtins.clear()
self._builtins_added = False
try:
del __builtin__.__dict__['__IPYTHON__active']
except KeyError:
pass