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Make event triggering robust to (un)registration....
Make event triggering robust to (un)registration. Event callbacks can register or unregister new callbacks for the same event while executing, and the previous triggering implementation allowed for event callbacks to be inadvertently skipped. The fix is to make a copy of the list of callbacks before executing any of them. With this change, the resulting semantics are simple: any callbacks registered before triggering are executed, and any new callbacks registered are only visible at the next triggering of the event. Note that this could potentially break existing callers who expected newly-appended callbacks were immediately executed. Fixes #9447. Originally based on a patch by @marksandler2.

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builtin_trap.py
114 lines | 4.2 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,
}
# Recursive reload function
try:
from IPython.lib import deepreload
if self.shell.deep_reload:
from warnings import warn
warn("Automatically replacing builtin `reload` by `deepreload.reload` is deprecated and will be removed in IPython 6.0, please import `reload` explicitly from `IPython.lib.deeprelaod", DeprecationWarning)
self.auto_builtins['reload'] = deepreload._dreload
else:
self.auto_builtins['dreload']= deepreload._dreload
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_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