Refer to instance of class in metaclass

[henribru]

In a meta class, is there a way to refer to an instance of the class that uses the metaclass? In a regular classmethod you can use Self, but in a meta class Self refers to the class itself, so that doesn't work:

https://pyright-play.net/?code=GYJw9gtgBALgngBwJYDsDmB9ApgDxllAZyTCKiQgTBBigGUsAbYAWACh2BjRgQ0MKgBZLPx5oswmDwAU8BFgCUALnZQ1UACZZgUBACNp3QgBooYPQCsl9JsAVQAtAD4bzawDpP7Lr35CRhGJY0hBYUtx8hAC8wqLikjzKUJ7u3hxsIFgAblg8jBhywbGB4u76CuyZOXkFiEUBQWUGxUHSCu1AA

https://mypy-play.net/?mypy=latest&python=3.11&gist=ac7550a5b678afea19f55d2d92e6eec8 (Mypy actually errors on the usage of Self in the meta class as well, though the result still matches Pyright)

[Gobot1234]

This is something that I considered when writing PEP 673 but the idea never went anywhere. However in your case you can probably just use a type var bound to Message and take that and return it from .pb

[henribru]

Ah, you're right of course, def pb(cls: type[M], obj: M) -> M: ... works like a charm. Thank you!