On 1 December 2017 at 19:15, Ronald Oussoren <ronaldoussoren@mac.com> wrote:
Maybe, but how would this work with super()? Super walks the MRO of type of the instance, but skips the class on the MRO. This is not equivalent to walking the MRO of the second class on the MRO when you use multiple inheritance,
This also has some other disadvantages. The first is that tp.__getdescriptor__ would replace the default behaviour for the entire MRO and it would be possible to have different behavior for classes on the MRO. The second, minor. one is that __getdescriptor__ would have to reimplement the default logic of walking the MRO, but that logic is fairly trivial.
I believe those can both be addressed by structuring the override a little differently, and putting it at the level of individual attribute retrieval on a specific class (rather than on all of its subclasses): def _PyType_Lookup(tp, name): mro = tp.mro() assert isinstance(mro, tuple) for base in mro: assert isinstance(base, type) try: getdesc = base.__dict__["__getdescriptor__"] except KeyError: try: return base.__dict__[name] except KeyError: pass else: try: return getdesc(tp, base, name) except AttributeError: pass return None In that version, the __getdescriptor__ signature would be: def __getdescriptor__(dynamic_cls, base_cls, attr): ... Cheers, Nick. -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia