Wrong interface for AsyncIterable

[ask]

In mypy AsyncIterable has an __anext__ method, but it should not: it should have __aiter__ only, but that is missing.

The code here:

typeshed/stdlib/3/typing.pyi

Lines 156 to 164 in 0709985

	class AsyncIterable(Generic[_T_co]):
	@abstractmethod
	def __anext__(self) -> Awaitable[_T_co]: ...
	class AsyncIterator(AsyncIterable[_T_co],
	Generic[_T_co]):
	@abstractmethod
	def __anext__(self) -> Awaitable[_T_co]: ...
	def __aiter__(self) -> 'AsyncIterator[_T_co]': ...

Should be:

class AsyncIterable(Generic[_T_co]):
    @abstractmethod
    def __aiter__(self) -> 'AsyncIterator[_T_co]': ...

class AsyncIterator(AsyncIterable[_T_co],
                    Generic[_T_co]):
    @abstractmethod
    def __anext__(self) -> Awaitable[_T_co]: ...
    def __aiter__(self) -> 'AsyncIterator[_T_co]': ...

I will try to figure out how to contribute a patch and tests :-)

[gvanrossum]

Could you show a small code fragment (or two) showing how the current stub is wrong, demonstrating that it works at runtime? A PR would also be welcome but the demonstration is key.

…

On Jun 7, 2017 11:57 AM, "Ask Solem" ***@***.***> wrote: In mypy AsyncIterable has an __anext__ method, but it should not, it should have __aiter__: An iterable is something that you can start iterating over, and it returns an Iterator. The code here: https://github.com/python/typeshed/blob/0709985d0c676127eae16e18e57104 16a9ec6da8/stdlib/3/typing.pyi#L156-L164 Should be: class AsyncIterable(Generic[_T_co]): @AbstractMethod def __aiter__(self) -> 'AsyncIterator[_T_co]': ... class AsyncIterator(AsyncIterable[_T_co], Generic[_T_co]): @AbstractMethod def __anext__(self) -> Awaitable[_T_co]: ... def __aiter__(self) -> 'AsyncIterator[_T_co]': ... That is, AsyncIterable does not have __anext__, it has only __aiter__. I will try to figure out how to contribute a patch and tests :-) — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#1396>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACwrMruw1jte8ENog1h4zHRBDE6LduPTks5sBvKtgaJpZM4NzI44> .

[ask]

I have the fix already and I could easily submit a PR, but I'm not sure where the tests go?

Would I add these tests to mypy perhaps? The test instructions mention running the mypy tests.

I will try to think of a code fragment also, but is not _collections_abc the canonical reference here:

https://github.com/python/cpython/blob/2e9cd5825c5ccdbb6f65a57c0c7941078e003c14/Lib/_collections_abc.py#L158-L170

There AsyncIterable has __aiter__, (no __anext__ as typeshed has as the only method),

[gvanrossum]

There is no convenient place to put the tests, I just want you to show the test code you ran manually to demonstrate that there is code that works at runtime but that is wrongly rejected by Python, to support this issue. You can put it in the introduction for the PR you submit. (Also link to this issue of course.)