Detect where __call__ is async def in context of iscoroutinefunction()

[peterschutt]

My use-case is basically a guard that I create with some state:

@put(guards=[CheckPayloadMismatch("id", "user_id").__call__])

Without passing through the __call__() method, starlite tries to call the instance sync.

As of 0.20.1, starlette themselves include this utility:

import asyncio
import functools
import typing


def is_async_callable(obj: typing.Any) -> bool:
    while isinstance(obj, functools.partial):
        obj = obj.func

    return asyncio.iscoroutinefunction(obj) or (
        callable(obj) and asyncio.iscoroutinefunction(obj.__call__)
    )

And a handful of test cases: https://github.com/encode/starlette/blob/master/tests/test__utils.py

Based on a quick search, there are 6 separate usages of iscoroutinefunction(): https://github.com/starlite-api/starlite/search?q=iscoroutinefunction. The most complex pattern of use is:

https://github.com/starlite-api/starlite/blob/f9893f28bc210e032e0527a61a6b695fc9e5c801/starlite/handlers/asgi.py#L43

Which would collapse down to a single call to is_async_callable() if we adopt such a function.

I'm happy to do the work if you give it the green light.

[Goldziher]

Go ahead, also - take my permission as granted

[peterschutt]

Closed by #162