the __future__ is now.
the __future__ is now.

File last commit:

r22814:2ed56dd7
r22963:2961b531
Show More
builtin_trap.py
103 lines | 3.6 KiB | text/x-python | PythonLexer
"""
A context manager for managing things injected into :mod:`__builtin__`.
Authors:
* Brian Granger
* Fernando Perez
"""
#-----------------------------------------------------------------------------
# Copyright (C) 2010-2011 The IPython Development Team.
#
# Distributed under the terms of the BSD License.
#
# Complete license in the file COPYING.txt, distributed with this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
from traitlets.config.configurable import Configurable
from IPython.utils.py3compat import builtin_mod, iteritems
from 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',
allow_none=True)
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,
}
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_mod.__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, orig):
"""Remove an added builtin and re-set the original."""
if orig is BuiltinUndefined:
del builtin_mod.__dict__[key]
else:
builtin_mod.__dict__[key] = orig
def activate(self):
"""Store ipython references in the __builtin__ namespace."""
add_builtin = self.add_builtin
for name, func in iteritems(self.auto_builtins):
add_builtin(name, func)
def deactivate(self):
"""Remove any builtins which might have been added by add_builtins, or
restore overwritten ones to their previous values."""
remove_builtin = self.remove_builtin
for key, val in iteritems(self._orig_builtins):
remove_builtin(key, val)
self._orig_builtins.clear()
self._builtins_added = False