python - How can I write asyncio coroutines that optionally act as regular functions?

Question

I'm writing a library that I'd like end-users to be able to optionally use as if its methods and functions were not coroutines.

For example, given this function:

@asyncio.coroutine
def blah_getter():
    return (yield from http_client.get('http://blahblahblah'))

An end user who doesn't care to use any asynchronous features in their own code, still has to import asyncio and run this:

>>> response = asyncio.get_event_loop().run_until_complete(blah_getter())

It would be cool if I could, inside of blah_getter determine if I was being called as a coroutine or not and react accordingly.

So something like:

@asyncio.coroutine
def blah_getter():
    if magically_determine_if_being_yielded_from():
        return (yield from http_client.get('http://blahblahblah'))
    else:
        el = asyncio.get_event_loop()
        return el.run_until_complete(http_client.get('http://blahblahblah'))

Answer 1

You need two functions -- asynchronous coroutine and synchronous regular function:

@asyncio.coroutine
def async_gettter():
    return (yield from http_client.get('http://example.com'))

def sync_getter()
    return asyncio.get_event_loop().run_until_complete(async_getter())

magically_determine_if_being_yielded_from() is actually event_loop.is_running() but I strongly don't recommend to mix sync and async code in the same function.