9.3. AsyncIO Awaitable¶

Since Python 3.5 PEP 492 -- Coroutines with async and await syntax
Object is an awaitable if it can be used in an await expression
Awaitable objects: Coroutines, Tasks, Futures
__await__ and await keyword

aw¶
awaitable¶: Object is an awaitable if it can be used in an await expression
aws¶: Awaitables
coroutine¶: Coroutine - a function which can run concurrently.
tasks¶: Runs thing in the "background". Can be awaited and cancelled.
future¶

An awaitable object generally implements an __await__() method. Coroutine objects returned from async def functions are awaitable. Note The generator iterator objects returned from generators decorated with types.coroutine() or asyncio.coroutine() are also awaitable, but they do not implement __await__().

object.__await__(self) Must return an iterator. Should be used to implement awaitable objects. For instance, asyncio.Future implements this method to be compatible with the await expression. 2

9.3.1. Awaitables¶

There are three main types of awaitable objects:

Coroutines,

Tasks,

Futures.

Coroutines are a low level concept and doesn't know about asyncio concepts such as EventLoop and Cancellations.

Tasks wraps around a coroutine object and allows for handling exceptions, gathering results etc.

9.3.2. Objects¶

Features of Python:

>>> from collections.abc import Awaitable
>>> from collections.abc import Coroutine

Features of AsyncIO library:

>>> from asyncio import Future
>>> from asyncio import Task

../../_images/asyncio-awaitables.png — Figure 9.11. Source: Langa, Ł. import asyncio: Learn Python's AsyncIO 1¶

9.3.3. Type Annotations¶

>>> from collections.abc import Awaitable
>>> from collections.abc import Coroutine
>>> from collections.abc import AsyncIterable
>>> from collections.abc import AsyncIterator
>>> from collections.abc import AsyncGenerator

9.3.4. References¶

1: Langa, Ł. import asyncio: Learn Python's AsyncIO. Year: 2020. Retrieved: 2022-03-10. URL: https://www.youtube.com/playlist?list=PLhNSoGM2ik6SIkVGXWBwerucXjgP1rHmB
2: Python core developers. Data model. Coroutines. Awaitable Objects. Year: 2022. Retrieved: 2022-04-01. URL: https://docs.python.org/3/reference/datamodel.html#awaitable-objects