If a class implements __dir__ to also return a number of attributes that aren't present in the class __dict__ inspect.classify_class_attrs gets confused and assumes the home class is None.

This in turn confused pydoc, docclass in pydoc assumes that the 'class' slot in the sequence returned by classify_class_attrs is actually a class and fails when it None (because None doesn't have a __name__ attribute).

I've classified this as "low" because I've found a useable workaround: I have implemented a "__objclass__" property for my custom descriptor and with that pydoc works.

It would be nice if pydoc wouldn't crash on this. One possible workaround: assume that the class is the inspected class when a name returned by dir(cls) cannot be found in one of the classes on the mro.

I'll provide a patch if this would be acceptable behavior.