__array_namespace__ type Hint

I hope this falls under the scope of this repo -

Is there any a way type-hint __array_namespace__? Is it even possible to do so, and it needs to be standardized, or maybe it’s not possible with current python type hinting system?

Motivation:

Suppose I want to write a function that will work in multiple conforming libraries, it will probably start with:

xp = x.__array_namespace__()

or, like in NEP-47:

def foo(x,y):
   xp = get_namespace(x,y)

In both cases, I want to be able to type check xp, and have auto-complete on xp in the various IDEs. (At least some auto-complete engines relay on static typing e.g https://github.com/microsoft/pyright)

Is this possible?

[rgommers]

Ah okay, got it now - types.ModuleType is already in the stdlib for Python 3.8, so it’s fine for us to use it now. And Mypy et al. supporting the new getattr behavior will materialize. So I’d say let’s use ModuleType as the annotation for the return type in implementations where the return type is actually a module.

Note that in the standard, the docs now say **out**: _<object>_ and I’m not sure we can do better there (aside from a recommendation), because the returned object doesn’t need to be a module, it could be a class instance for example.

[BvB93]

Note that in the standard, the docs now say **out**: _<object>_ and I’m not sure we can do better there (aside from a recommendation), because the returned object doesn’t need to be a module, it could be a class instance for example.

I feel that Any would be a small improvement over object here; it is designed as the ultimate placeholder, used for situations situation wherein some specific(-ish) type is involved, but you’re not sure how to express it. In contrast, object is generally reserved for situation wherein truly any arbitrary object is considered valid.