Quick Python: Async Callbacks

Brandon Rozek

July 11, 2020

I’ve written a post on using callbacks in Python. Though to add callbacks to asyncio functions, you’ll have to interact with the loop object directly. Replace the emit function in the previous post with the following:

class Application:
    # ...
    def emit(self, message):
        for callback in self.callbacks:
            if asyncio.iscoroutine(callback):
                loop = asyncio.get_running_loop()
                loop.call_soon(
                    functools.partial(
                        asyncio.ensure_future,
                        callback(message)
                    )
                )
            else:
                callback(message)