asyncio.iscoroutinefunction returns False for asynchronous generator

Question

The following asynchronous generator code is taked straight out of PEP525:

async def gen():
    await asyncio.sleep(0.1)
    v = yield 42
    print(v)
    await asyncio.sleep(0.2)

However when I call (with python3.6):

print(asyncio.iscoroutinefunction(gen), asyncio.iscoroutine(gen))

I get:

False, False

Why does asynchronous generator fails to identify as a coroutine function?

Is there another way to identify it as a coroutine function?

Answer 1

You want to use inspect.isasyncgenfunction() (and inspect.isasyncgen() for the result of calling gen()):

>>> import inspect
>>> print(inspect.isasyncgenfunction(gen), inspect.isasyncgen(gen()))
True True

There is no type hierarchy relationship between async functions and async generator functions.

Also, the only reason the asyncio.iscoroutine*() functions exist at all is to support the legacy generator-based @asyncio.coroutine decorator, which can't be used to create async generators. If you don't need to support older codebases that might still use those (so predating Python 3.5) I'd just stick with the inspect.is*() functions.