Fixed #8285: signal handlers that aren't functions work under DEBUG. This...

        """

        from django.conf import settings

        # If DEBUG is on, check that we got a good receiver

        if settings.DEBUG:

            import inspect

            assert inspect.getargspec(receiver)[2] is not None, \

            assert callable(receiver), "Signal receivers must be callable."

            # Check for **kwargs

            # Not all callables are inspectable with getargspec, so we'll

            # try a couple different ways but in the end fall back on assuming

            # it is -- we don't want to prevent registration of valid but weird

            # callables.

            try:

                argspec = inspect.getargspec(receiver)

            except TypeError:

                try:

                    argspec = inspect.getargspec(receiver.__call__)

                except (TypeError, AttributeError):

                    argspec = None

            if argspec:

                assert argspec[2] is not None, \

                    "Signal receivers must accept keyword arguments (**kwargs)."

        if dispatch_uid:

    print 'pre_delete signal,', instance

    print 'instance.id is not None: %s' % (instance.id != None)

def post_delete_test(signal, sender, instance, **kwargs):

# #8285: signals can be any callable

class PostDeleteHandler(object):

    def __call__(self, signal, sender, instance, **kwargs):

        print 'post_delete signal,', instance

        print 'instance.id is None: %s' % (instance.id == None)

post_delete_test = PostDeleteHandler()

__test__ = {'API_TESTS':"""

>>> models.signals.pre_save.connect(pre_save_test)

>>> models.signals.post_save.connect(post_save_test)