At 09:35 AM 5/9/2006 -0700, Bill Janssen wrote: >Phillip Eby writes: > > In Haskell, interfaces are defined using "typeclasses". A typeclass is > > basically a collection of generic functions. For example, you could > define > > ... > > Further, Haskell has a concept of "typeclass instances" which basically > > give you adaptation. For example, suppose I have some generic functions > >Thanks, Phillip. That's essentially what I'm talking about with CL >mixins, as well (though instead of typeclass instances you usually >have mixin implementations which are "mixed" into the class which >wishes to provide the interface, to give it the methods).
Unless this can be done by a third party, it's not at all the same thing. Currently in Python for a third party to add a mixin, they would have to hack the class's __bases__, which I am not suggesting here at all. In fact, it's pretty much the opposite of what I'm suggesting -- you shouldn't *have* to make such declarations, let alone monkeypatch a class's __bases__. >That's what >I think Py3K should be using, too, instead of "duck typing", which for >some reason has come to be thought of (wrongly) as a "feature". I don't see that discussion as being even remotely related to what I'm talking about, so please don't count my comments as being against duck typing or supporting its removal. Indeed, I consider my suggestion to be support for *extending* duck typing, and a vote *against* typing by inheritance. You seem to be very confused about what I said. _______________________________________________ Python-3000 mailing list Python-3000@python.org http://mail.python.org/mailman/listinfo/python-3000 Unsubscribe: http://mail.python.org/mailman/options/python-3000/archive%40mail-archive.com
