OK, I see this point now. Still looking for time to review the rest of your PEP!
--Guido (mobile) On Jul 3, 2016 3:29 PM, "Martin Teichmann" <lkb.teichm...@gmail.com> wrote: > Hi Guido, > > sorry I missed your post... > > >> One of the big issues that makes library authors reluctant to use > >> metaclasses > >> (even when they would be appropriate) is the risk of metaclass > conflicts. > > > > Really? I've written and reviewed a lot of metaclasses and this has never > > worried me. The problem is limited to multiple inheritance, right? I > worry a > > lot about MI being imposed on classes that weren't written with MI in > mind, > > but I've never particularly worried about the special case of > metaclasses. > > Yes, the problem only arises with MI. Unfortunately, that's not > uncommon: if you want to implement an ABC with a class from a > framework which uses metaclasses, you have a metaclass conflict. So > then you start making MyFrameworkABCMeta-classes. > > The worst is if you already have a framework with users out there. No > way you add a metaclass to your class, however convenient it would > be. Because you never now if some user out there had gotten the idea > to implement an ABC with it. Sure, you could let your metaclass > inherit from ABCMeta, but is this really how it should be done? > > (This has already been mentioned by others over at python-ideas: > https://mail.python.org/pipermail/python-ideas/2016-February/038506.html) > > Greetings > > Martin > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > https://mail.python.org/mailman/options/python-dev/guido%40python.org >
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