`#[new]` which is also a `#[classmethod]`

[davidhewitt]

Discussed in #3075

^{Originally posted by adriangb March 29, 2023}
As far as I can tell, #[new] has to be a static method. It's a classmethod in Python, could it be made the same in PyO3? Context: I'd like to get the class name as seen by Python for the failure case of calling new.

[stuhood]

Have you already started this? I can look at it today if not.

[davidhewitt]

I have not, please go ahead, thanks! I think the challenge is that we currently special case new in the backend (see FnType enum iirc). Any refactoring you fancy is welcome, and feel free to post questions here or in a PR; I'll answer when I can...

[stuhood]

Posted over here: #3157 ... thanks!