Well, they're not synonymous. At least not in that context. If you haven't already tried it, what you're doing will fail for instances as well. Look in typeobject.c to see why. The gist of it is that the special methods are looked up on the type rather than the instance (on the metaclass rather than on the class, in your case), so the internal lookup mechanism ignore instance attributes completely in this case.
-- http://mail.python.org/mailman/listinfo/python-list
