On Apr 14, 2011, at 3:32 PM, Ricardo Kirkner wrote: >> >> What would the semantics be of a super that intentially calls all siblings? >> In particular what is the return value of such a call? The implementation >> can't know how to combine the implementations in the inheritance chain and >> should refuse the tempation to guess. > > I'll give you the example I came upon: > > I have a TestCase class, which inherits from both Django's TestCase > and from some custom TestCases that act as mixin classes. So I have > something like > > class MyTestCase(TestCase, Mixin1, Mixin2): > ... > > now django's TestCase class inherits from unittest2.TestCase, which we > found was not calling super. Even if this is a bug and should be fixed > in unittest2, this is an example where I, as a consumer of django, > shouldn't have to be worried about how django's TestCase class is > implemented. Since I explicitely base off 3 classes, I expected all 3 > classes to be initialized, and I expect the setUp method to be called > on all of them. > > If I'm assuming/expecting unreasonable things, please enlighten me.
For cooperative-multiple-inheritance to work, the classes need to cooperate by having been designed to work together in a series of cooperative super calls. If an external non-cooperative class needs to be used, then it should be wrapped in a class that makes an explicit __init__ call to the external class and then calls super().__init__() to continue the forwarding. Raymond _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
