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Fixed #21840 -- Moved dunder methods from SimpleLazyObject to LazyObject.

Browse source 
This commit also added tests for LazyObject and refactored
the testsuite of SimpleLazyObject so that it can share
test cases with LazyObject.
This commit is contained in:
Baptiste Mispelon 2014-01-29 05:53:30 +01:00
parent 4b4c704517
commit 61917aa08b
3 changed files with 340 additions and 227 deletions
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116
django/utils/functional.py
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@ -265,9 +265,62 @@ class LazyObject(object):
"""
raise NotImplementedError('subclasses of LazyObject must provide a _setup() method')
# Because we have messed with __class__ below, we confuse pickle as to what
# class we are pickling. It also appears to stop __reduce__ from being
# called. So, we define __getstate__ in a way that cooperates with the way
# that pickle interprets this class. This fails when the wrapped class is
# a builtin, but it is better than nothing.
def __getstate__(self):
if self._wrapped is empty:
self._setup()
return self._wrapped.__dict__
# Python 3.3 will call __reduce__ when pickling; this method is needed
# to serialize and deserialize correctly.
@classmethod
def __newobj__(cls, *args):
return cls.__new__(cls, *args)
def __reduce_ex__(self, proto):
if proto >= 2:
# On Py3, since the default protocol is 3, pickle uses the
# ``__newobj__`` method (& more efficient opcodes) for writing.
return (self.__newobj__, (self.__class__,), self.__getstate__())
else:
# On Py2, the default protocol is 0 (for back-compat) & the above
# code fails miserably (see regression test). Instead, we return
# exactly what's returned if there's no ``__reduce__`` method at
# all.
return (copyreg._reconstructor, (self.__class__, object, None), self.__getstate__())
def __deepcopy__(self, memo):
if self._wrapped is empty:
# We have to use type(self), not self.__class__, because the
# latter is proxied.
result = type(self)()
memo[id(self)] = result
return result
return copy.deepcopy(self._wrapped, memo)
if six.PY3:
__bytes__ = new_method_proxy(bytes)
__str__ = new_method_proxy(str)
__bool__ = new_method_proxy(bool)
else:
__str__ = new_method_proxy(str)
__unicode__ = new_method_proxy(unicode)
__nonzero__ = new_method_proxy(bool)
# Introspection support
__dir__ = new_method_proxy(dir)
# Need to pretend to be the wrapped class, for the sake of objects that
# care about this (especially in equality tests)
__class__ = property(new_method_proxy(operator.attrgetter("__class__")))
__eq__ = new_method_proxy(operator.eq)
__ne__ = new_method_proxy(operator.ne)
__hash__ = new_method_proxy(hash)
# Dictionary methods support
__getitem__ = new_method_proxy(operator.getitem)
__setitem__ = new_method_proxy(operator.setitem)
@ -303,51 +356,6 @@ class SimpleLazyObject(LazyObject):
def _setup(self):
self._wrapped = self._setupfunc()
if six.PY3:
__bytes__ = new_method_proxy(bytes)
__str__ = new_method_proxy(str)
else:
__str__ = new_method_proxy(str)
__unicode__ = new_method_proxy(unicode)
def __deepcopy__(self, memo):
if self._wrapped is empty:
# We have to use SimpleLazyObject, not self.__class__, because the
# latter is proxied.
result = SimpleLazyObject(self._setupfunc)
memo[id(self)] = result
return result
else:
return copy.deepcopy(self._wrapped, memo)
# Because we have messed with __class__ below, we confuse pickle as to what
# class we are pickling. It also appears to stop __reduce__ from being
# called. So, we define __getstate__ in a way that cooperates with the way
# that pickle interprets this class. This fails when the wrapped class is
# a builtin, but it is better than nothing.
def __getstate__(self):
if self._wrapped is empty:
self._setup()
return self._wrapped.__dict__
# Python 3.3 will call __reduce__ when pickling; this method is needed
# to serialize and deserialize correctly.
@classmethod
def __newobj__(cls, *args):
return cls.__new__(cls, *args)
def __reduce_ex__(self, proto):
if proto >= 2:
# On Py3, since the default protocol is 3, pickle uses the
# ``__newobj__`` method (& more efficient opcodes) for writing.
return (self.__newobj__, (self.__class__,), self.__getstate__())
else:
# On Py2, the default protocol is 0 (for back-compat) & the above
# code fails miserably (see regression test). Instead, we return
# exactly what's returned if there's no ``__reduce__`` method at
# all.
return (copyreg._reconstructor, (self.__class__, object, None), self.__getstate__())
# Return a meaningful representation of the lazy object for debugging
# without evaluating the wrapped object.
def __repr__(self):
@ -355,16 +363,16 @@ class SimpleLazyObject(LazyObject):
repr_attr = self._setupfunc
else:
repr_attr = self._wrapped
return '<SimpleLazyObject: %r>' % repr_attr
return '<%s: %r>' % (type(self).__name__, repr_attr)
# Need to pretend to be the wrapped class, for the sake of objects that
# care about this (especially in equality tests)
__class__ = property(new_method_proxy(operator.attrgetter("__class__")))
__eq__ = new_method_proxy(operator.eq)
__ne__ = new_method_proxy(operator.ne)
__hash__ = new_method_proxy(hash)
__bool__ = new_method_proxy(bool) # Python 3
__nonzero__ = __bool__ # Python 2
def __deepcopy__(self, memo):
if self._wrapped is empty:
# We have to use type(self), not self.__class__, because the
# latter is proxied.
result = SimpleLazyObject(self._setupfunc)
memo[id(self)] = result
return result
return copy.deepcopy(self._wrapped, memo)
class lazy_property(property):