Unverified Kaydet (Commit) 996859a9 authored tarafından Yury Selivanov's avatar Yury Selivanov Kaydeden (comit) GitHub

bpo-34790: [docs] Passing coroutines to asyncio.wait() can be confusing. (GH-9543)

üst 22ef31d0
......@@ -472,14 +472,20 @@ Waiting Primitives
return_when=ALL_COMPLETED)
Run :ref:`awaitable objects <asyncio-awaitables>` in the *aws*
sequence concurrently and block until the condition specified
set concurrently and block until the condition specified
by *return_when*.
If any awaitable in *aws* is a coroutine, it is automatically
scheduled as a Task.
scheduled as a Task. Passing coroutines objects to
``wait()`` directly is deprecated as it leads to
:ref:`confusing behavior <asyncio_example_wait_coroutine>`.
Returns two sets of Tasks/Futures: ``(done, pending)``.
Usage::
done, pending = await asyncio.wait(aws)
The *loop* argument is deprecated and scheduled for removal
in Python 4.0.
......@@ -514,9 +520,35 @@ Waiting Primitives
Unlike :func:`~asyncio.wait_for`, ``wait()`` does not cancel the
futures when a timeout occurs.
Usage::
.. _asyncio_example_wait_coroutine:
.. note::
done, pending = await asyncio.wait(aws)
``wait()`` schedules coroutines as Tasks automatically and later
returns those implicitly created Task objects in ``(done, pending)``
sets. Therefore the following code won't work as expected::
async def foo():
return 42
coro = foo()
done, pending = await asyncio.wait({coro})
if coro in done:
# This branch will never be run!
Here is how the above snippet can be fixed::
async def foo():
return 42
task = asyncio.create_task(foo())
done, pending = await asyncio.wait({task})
if task in done:
# Everything will work as expected now.
Passing coroutine objects to ``wait()`` directly is
deprecated.
.. function:: as_completed(aws, \*, loop=None, timeout=None)
......
Document how passing coroutines to asyncio.wait() can be confusing.
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