diff options
Diffstat (limited to 'django/utils/functional.py')
| -rw-r--r-- | django/utils/functional.py | 116 |
1 files changed, 62 insertions, 54 deletions
diff --git a/django/utils/functional.py b/django/utils/functional.py index 9668bc682b..35f48c6251 100644 --- a/django/utils/functional.py +++ b/django/utils/functional.py @@ -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): |