Pedro Werneck wrote: >>> class M_A(type): pass ...
>>> class A: __metaclass__ = M_A ... >>> class M_B(M_A): pass ... >>> class B(A): __metaclass__ = M_B ... >>> class C(B): __metaclass__ = M_A ... >>> C.__class__ <class '__main__.M_B'> >>> C.__metaclass__ <class '__main__.M_A'> > Is this supposed to happen ? Yes, or at least I feel this is a reasonable behavior. You get the stricted metaclass(M_B) and not the more generic one (M_A), so you don't lose anything. Remember that given a class C, its metaclass is given by C.__class__, not by C.__metaclass__, despite the name. I wrote some code to automatically solve metaclass conflicts (see for instance my Oxford lectures http://www.phyast.pitt.edu/~micheles/oxford-lectures.zip) and it works in the same way, it uses the strictest metaclass. You argue that in this case an error should be raised, since "errors should never pass silently". May be. You are free to post the bug report and look at the opinions of the developers. I am happy enough with the current behavior and I would just update the docs. Michele Simionato Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list
