Fixed #20212 - __reduce__ should only be defined for Py3+.

from django.utils import six

try:

    import copyreg

except ImportError:

    import copy_reg as copyreg

# You can't trivially replace this with `functools.partial` because this binds

# to classes and returns bound instances, whereas functools.partial (on

            self._setup()

        return self._wrapped.__dict__

    # Python 3.3 will call __reduce__ when pickling; these methods are needed

    # to serialize and deserialize correctly. They are not called in earlier

    # versions of Python.

    # 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__(self):

    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.

        self.assertNotEqual(lazy1, lazy3)

        self.assertTrue(lazy1 != lazy3)

        self.assertFalse(lazy1 != lazy2)

    def test_pickle_py2_regression(self):

        from django.contrib.auth.models import User

        # See ticket #20212

        user = User.objects.create_user('johndoe', 'john@example.com', 'pass')

        x = SimpleLazyObject(lambda: user)

        # This would fail with "TypeError: can't pickle instancemethod objects",

        # only on Python 2.X.

        pickled = pickle.dumps(x)

        # Try the variant protocol levels.

        pickled = pickle.dumps(x, 0)

        pickled = pickle.dumps(x, 1)

        pickled = pickle.dumps(x, 2)

        if not six.PY3:

            import cPickle

            # This would fail with "TypeError: expected string or Unicode object, NoneType found".

            pickled = cPickle.dumps(x)