Petr Viktorin schrieb am 14.01.20 um 14:37:
It also includes a more drastic change: it removes the MRO walker from the proposal. Reflecting on the feedback, it became clear to me that a MRO walker, as it was described, won't give correct results in all cases: specifically, is a slot is overridden by setting a special method from Python code, the walker won't be able to find module. Think something like: c_add = Class.__add__ # where nb_add uses the MRO walker Class.__add__ = lambda *args: "evil" c_add(Class(), 0) # Exception: Defining type has not been found.
This can be solved, but it will need a different design and more discussion. I'd rather defer it to the future. Meanwhile, extension authors can use their own MRO walker if they're OK with some surprising edge cases.
I read the last update. I can't say I'm happy about the removal since I was seeing the MRO walker function as a way to hide internals so that extension authors can start using it and CPython can adapt the internals later. But I do see that there are issues with it, and I accept your choice to keep the PEP even more minimal than it already was.
Are there any more points to discuss? If not, I would soon like to accept the PEP, so that we can focus more on the implementation and usage.