gh-140382: Add support for __getattr__ method to Argument Clinic

[StanFromIreland]

• Issue: Support __getattr__ method in AC #140382

[merwok]

Could you create a new issue for this, and tag people interested in AC?

[StanFromIreland]

I can create a new issue, but all CODEOWNERs have already been notified. Do you have anyone else in mind?

[ZeroIntensity]

Wouldn't it make more sense to just support arbitrary dunder methods? __getattr__ isn't very common in C code, among other things.

[AA-Turner]

I'm also not convinced this is worth it. __getattr__() really ought to be implemented at the Python level, modules implemented entirely in C (like zlib) are very much a special case, and aren't used for new stdlib modules.

A

[ZeroIntensity]

On the other hand, I would be very supportive of allowing arbitrary dunders in AC, though I suspect that would be a lot of extra work (because we would need to map dunders to PyTypeObject fields).

[merwok]

I can create a new issue, but all CODEOWNERs have already been notified. Do you have anyone else in mind?

No, it’s just the general principle that «should we do?» discussions happen in issues (and when needed on the forums), then the PR can host «how to do?» discussions.

[skirpichev]

Wouldn't it make more sense to just support arbitrary dunder methods?

I think it's ok to add support of specific dunders on-demand. It's not too helpful in general, because sometimes we can do too much with slots, even override the docstring.

But please think about more generic case. For example, for most dunders we have very specific function signatures. It will be redundant and error-prone to specify this stuff by hand.

[skirpichev]

Suggested change

	name: object
	name: str

I think we want here a string, isn't? And remove PyUnicode_Check() in zlib___getattr__()

Also, we want this always. Maybe per-default the AC should set an appropriate signature?