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Control monkey-patch scope with a context manager
from __future__ import with_statement
from types import ClassType, MethodType, TypeType
class Patch(object):
class Missing:
def __init__(self, obj, **kwargs):
self._obj = obj
self._patches = kwargs
def __enter__(self):
self._saved = {}
for name, method in self._patches.iteritems():
self._saved[name] = self._obj.__dict__.get(name, self.Missing)
setattr(self._obj, name, self._rebind_method(method))
def __exit__(self, exc_type, exc_value, traceback):
for name, method in self._saved.iteritems():
if method is not self.Missing:
setattr(self._obj, name, method)
delattr(self._obj, name)
def _rebind_method(self, method):
if not method:
method = self._get_noop_method()
if isinstance(method, MethodType):
method = self._get_unbound_method(method)
if not isinstance(self._obj, (ClassType, TypeType)):
method = self._bind_method_to_instance(method)
return method
def _get_noop_method(self):
return lambda *args, **kwargs: None
def _get_unbound_method(self, method):
return method.im_func
def _bind_method_to_instance(self, method):
return method.__get__(self._obj, type(self._obj))
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