On 23 July 2016 at 22:26, Ronald Oussoren <ronaldousso...@mac.com> wrote: > I’m currently working on getting the patch in 18181 up-to-date w.r.t. the > current trunk, the patch in the issue no longer applies cleanly. After that > I’ll try to think up some tests that seriously try to break the new > behaviour, and I want to update a patch I have for PyObjC to make use of the > new functionality to make sure that the PEP actually fixes the issues I had > w.r.t. builtin.super’s behavior.
You may also want to check compatibility with Martin's patch for PEP 487 (__init_subclass__ and __set_name__) at http://bugs.python.org/issue27366 I don't *think* it will conflict, but "try it and see what happens" is generally a better idea for the descriptor machinery than assuming changes are going to be non-conflicting :) > What is the best way forward after that? As before this is a change in > behavior that, unsurprisingly, few core devs appear to be comfortable with > evaluating, combined with new functionality that will likely see little use > beyond PyObjC. You may want to explicitly ping the https://github.com/ipython/traitlets developers to see if this change would let them do anything they currently find impractical or impossible. As far as Mark's concern about a non-terminating method definition goes, I do think you need to double check how the semantics of object.__getattribute__ are formally defined. >>> class Meta(type): ... def __getattribute__(self, attr): ... print("Via metaclass!") ... return super().__getattribute__(attr) ... >>> class Example(metaclass=Meta): pass ... >>> Example.mro() Via metaclass! [<class '__main__.Example'>, <class 'object'>] Where the current PEP risks falling into unbounded recursion is that it appears to propose that the default type.__getdescriptor__ implementation be defined in terms of accessing cls.__dict__, but a normal Python level access to "cls.__dict__" would go through the descriptor machinery, triggering an infinite regress. The PEP needs to be explicit that where "cls.__dict__" is written in the definitions of both the old and new lookup semantics, it is *not* referring to a normal class attribute lookup, but rather to the interpreter's privileged access to the class namespace (e.g. direct 'tp_dict' access in CPython). Cheers, 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
