On 2 April 2015 at 16:38, PJ Eby <p...@telecommunity.com> wrote: > > IOW, there's no need to modify the core just to have *that* feature, > since if you control the base class you can already do what PEP 487 > does in essentially every version of Python, ever. If that's all PEP > 487 is going to do, it should just be a PyPI package on a > stdlib-inclusion track, not a change to core Python. It's not > actually adding back any of the dynamicness (dynamicity? > hookability?) that PEP 3115 took away.
The specific feature that PEP 487 is adding is the ability to customise creation of subclasses without risking the introduction of a metaclass conflict. That allows it to be used in situations where adopting any of the existing metaclass based mechanisms would require a potential compatibility break (as well as being far more approachable as a mechanism than the use of custom metaclasses). The gap I agree this approach leaves is a final post-namespace-execution step that supports establishing any class level invariants implied by decorators and other functions used in the class body. Python 2 allowed that to be handled with a dynamically generated __metaclass__ and PEP 422 through __autodecorate__, while PEP 487 currently has no equivalent mechanism. Regards, Nick. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia _______________________________________________ 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/archive%40mail-archive.com
