[Python-ideas] Eliminating special method lookup (was Re: Missing Core Feature: + - * / | & do not call __getattr__)

[Ronald Oussoren]

> On 06 Dec 2015, at 13:58, Nick Coghlan <ncoghlan at gmail.com> wrote:
> 
> On 6 December 2015 at 11:56, Andrew Barnert via Python-ideas
> <python-ideas at python.org> wrote:
>> On Dec 5, 2015, at 09:30, Guido van Rossum <guido at python.org> wrote:
>>> (However, giving the metaclass more control is not unreasonable. There also seems to be some interesting behavior here related to slots.)
>> 
>> I'm not sure what you're suggesting here. That implementations can let a metaclass __getattribute__ hook special method lookup, but some implementations (including CPython 3.6) won't do so?
> 
> Ronald Oussoren has elaborated on that aspect of the problem in his
> __getdescriptor__ PEP: https://www.python.org/dev/peps/pep-0447/
> 
> The main reason it's separate from __getattribute__ is that this is
> necessary to avoid changing the semantics of super.__getattribute__,
> but it's also the case that things would otherwise get quite confusing
> with object.__getattribute__ and super.__getattribute__ potentially
> calling type.__getattribute__, which then has the potential for
> strange consequences when you consider that "type" is itself an
> instance of "type".
> 
> My recollection of the previous round of discussions on that PEP is
> that we're actually pretty happy with the design - it's now dependent
> on someone with the roundtuits to update the reference implementation
> to match the current PEP text and the head of the current development
> branch.

Mark Shannon had some concerns about how my proposal affects the object model.  I didn’t quite get his concerns at the time, probably because I was thinking to much about the implementation. 

BTW. Sorry about not following up at the time, I got sucked back into work :-(.  My plan for the week is to get a version of PyObC with support of OSX 10.11 on PyPI, after that I hope to return to PEP 447.

Ronald