test: update mypy typings

[kuwv]

No description provided.

[kuwv]

@bitprophet this should resolve multiple open issues with typing.

[kuwv]

@bitprophet do you think you can review this soon?

It should resolve multiple outstanding issues.

[kuwv]

@Dreamsorcerer fysa

[Dreamsorcerer]

The TypeVar is not being used correctly in this function. Either use Task[Any], or if you want to spend a bit more time on it, you could try and type it properly.

I think the correct signature would look something along the lines of:

@overload
def task(arg: T, *, klass: Callable[[T]], U], **kwargs: Any) -> U:
    ...
@overload
def task(arg: T, **kwargs: Any) -> Task[T]:
    ...
@overload
def task(*args, klass: Callable[[Callable], T], **kwargs: Any) -> Callable[[Callable], T]:
    ...
@overload
def task(*args: Any, **kwargs: Any) -> Callable[[T], Task[T]]:  # T should actually be bound to Callable on this one.
    ...

But, frankly, it's rather complicated.

[kuwv]

This is following the recommendation provided by mypy documentation: https://mypy.readthedocs.io/en/stable/generics.html#declaring-decorators

Commented on the wrong example.

[Dreamsorcerer]

The mistake is that a TypeVar is being used as a return type, but does not appear in the parameters (or anywhere else), which means that it is not doing the job of a TypeVar. The point of a TypeVar is to infer the precise type based on context. e.g. def foo(a: T) -> T: means that the return type will be the same as the input type. If you only put it in one place, then this gives no information at all (it wouldn't surprise me if mypy were to produce a type error in future, due to this being obviously incorrect usage).

[Dreamsorcerer]

Seems that mypy already produces an error for this, but it doesn't trigger with a Generic:
python/mypy#16113

[Dreamsorcerer]

Maybe this'll be fixed by the above comment, but if not, it'd be better to type ignore than cast here, given that it is literally not a Task being returned.

[kuwv]

This is following the recommendation provided by mypy documentation: https://mypy.readthedocs.io/en/stable/generics.html#declaring-decorators

[Dreamsorcerer]

My point was that this is not a Task. The docs you point to are accepting a function and returning a function, the cast is to the function type. This is returning a function and then you're casting it as a Task.

docs:

F = TypeVar('F', bound=Callable[..., Any])
def printing_decorator(func: F) -> F:
    def wrapper(*args, **kwds):
        ...
    return cast(F, wrapper)  # wrapper is the same as F as it is a function which passes through the call.

here:

def task(*args: Any, **kwargs: Any) -> Task[T]:
    def inner(body: Callable) -> Task[T]:
        ...
    return cast(Task[T], inner)  # inner is clearly not a Task

[joaonc]

Would love to see this merged. Per https://bitprophet.org/projects

Upcoming
2024.07-8: will likely focus on Invoke features and major bugfixes

So maybe that will happen soon 🤞

[kuwv]

@bitprophet do you have time to look at this patch?