gh-111874: Call __set_name__ on objects that define the method inside a typing.NamedTuple class dictionary as part of the creation of that class

[AlexWaygood]

Closes #111874

• Issue: Objects in NamedTuple class namespaces don't have __set_name__ called on them #111874

[serhiy-storchaka]

LGTM, but I have few minor suggestions.

[AlexWaygood]

Thanks @serhiy-storchaka! I applied your suggestions; would you mind taking another look? I discovered another interesting thing in the process: __set_name__ was also not being called for the values of annotated fields (which become namedtuple members). I changed that so that __set_name__ is called on these field values also. It's consistent with what e.g. dataclasses does:

Python 3.13.0a1+ (heads/main:e5dfcc2b6e, Nov 15 2023, 17:23:51) [MSC v.1932 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> from dataclasses import dataclass
>>> class Vanilla:
...     def __set_name__(self, owner, name):
...         self.name = name
...
>>> @dataclass
... class Foo:
...     v: Vanilla = Vanilla()
...
>>> f = Foo()
>>> f.v.name
'v'

[serhiy-storchaka]

I am not sure that __set_name__ should be called for annotated fields.

[AlexWaygood]

I am not sure that __set_name__ should be called for annotated fields.

Yes, I could be persuaded either way there.

[JelleZijlstra]

Is it worth adding a test for the case where this yields some other exception (e.g. due to a weird metaclass)?

[AlexWaygood]

Good catch. Seems like for normal classes, if any strange exception is raised when trying to lookup __set_name__, the interpreter just swallows it and moves on:

>>> class Meta(type):
...     def __getattribute__(self, attr):
...         if attr == "__set_name__":
...             raise BaseException("NO")
...
>>> class VeryAnnoying(metaclass=Meta): pass
...
>>> class Foo:
...     attr = VeryAnnoying()
...
>>>

We should do the same here (though I don't want to swallow BaseExceptions, since that would catch KeyboardInterrupt, SystemExit, etc. -- I think I'll just use except Exception).

[AlexWaygood]

Addressed in 1909fd5

[serhiy-storchaka]

Seems like for normal classes, if any strange exception is raised when trying to lookup __set_name__, the interpreter just swallows it and moves on:

It looks like a bug. I do not think it should be reproduced here. It is better to fix it for normal classes.

[AlexWaygood]

Okay, I opened #112453, and will revert the changes made here that reproduce the bug

[serhiy-storchaka]

LGTM.

Few minor suggestions which you can ignore.

[AlexWaygood]

Thanks for the reviews!