Introspection functions from the inspect module are designed for native types.
Introspection functions from asyncio are designed for what asyncio treats as
coroutines. Consider this example:
@asyncio.coroutine
def coro():
print(‘hello’)
‘asyncio.iscoroutinefunction' will return ‘True' for ‘coro’, because it knows
how specifically asyncio wraps non-generator functions. To make
‘inspect.iscoroutinefunction’ recognize ‘coro’ as a coroutine function we would
need to make ‘inspect’ aware of asyncio. But asyncio is just one user of
async/await and generator-based coroutines. Twisted and Tornado have their own
coroutine decorators, we can’t make inspect to recognize coroutines from them
all.
Yury
> On Nov 8, 2016, at 12:03 AM, Justin Mayfield <too...@gmail.com> wrote:
>
> I know this is documented in PEP 492 but I'm struggling to understand why the
> inspect module has several test functions (iscoroutine, iscoroutinefunction,
> isawaitable) that only work for native coros. Comparatively the same
> functions in the asyncio module work for both native and generator based
> coros.
>
> It was an interesting exercise for me to figure this out the hard way so it's
> safe to say there is peril in this distinction for at least one developer.
> Furthermore, the docs for both sets of functions don't elude to these subtle
> but important distinctions.
>
> Are there good reasons for this distinction going forward?
>
> Here are some surprising (to me) tests...
>
> Python 3.5.2 (default, Oct 14 2016, 12:54:53)
> [GCC 6.2.1 20160916 (Red Hat 6.2.1-2)] on linux
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import inspect
> >>> import asyncio
> >>> inspect.iscoroutinefunction(asyncio.sleep)
> False
> >>> asyncio.iscoroutinefunction(asyncio.sleep)
> True
> >>> inspect.iscoroutine(asyncio.sleep(1))
> False
> >>> asyncio.iscoroutine(asyncio.sleep(1))
> True
> >>> inspect.isawaitable(asyncio.sleep(1))
> 256
>
>
> The last test is particularly interesting; At least it's truthy?
>
