asyncio.wait should accept generator of tasks as first argument

[jnwatson]

BPO	34349
Nosy	@asvetlov, @1st1, @jnwatson, @tirkarthi, @epiphyte

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2018-08-06.19:41:06.692>
labels = ['3.8', 'expert-asyncio']
title = 'asyncio.wait should accept generator of tasks as first argument'
updated_at = <Date 2018-08-07.14:20:15.310>
user = 'https://github.com/jnwatson'

bugs.python.org fields:

activity = <Date 2018-08-07.14:20:15.310>
actor = 'yselivanov'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['asyncio']
creation = <Date 2018-08-06.19:41:06.692>
creator = 'jnwatson'
dependencies = []
files = []
hgrepos = []
issue_num = 34349
keywords = []
message_count = 2.0
messages = ['323217', '323241']
nosy_count = 5.0
nosy_names = ['asvetlov', 'yselivanov', 'jnwatson', 'xtreak', 'epiphyte']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue34349'
versions = ['Python 3.8']

Linked PRs

• GH-78530: add support for generators in asyncio.wait #102761
• [3.11] GH-78530: clarify docs for generators yielding tasks in asyncio.wait and asyncio.as_completed #103748

[jnwatson]

Currently, passing a generator of coroutines or futures as the first parameter of asyncio.wait raises a TypeError. This is in conflict with the documentation calling the first parameter a "sequence".

Line in question. https://github.com/python/cpython/blob/3.7/Lib/asyncio/tasks.py#L347

Generators are indeed coroutines, so the check to validate that the first parameter is not a coroutine or a future is too specific.

I'd suggest replacing that line with a check that the passed-in parameter is iterable, i.e. hasattr(futures, __iter__).

[1st1]

Since we're deprecating generator-based coroutines anyways, I too think that the check can be relaxed.

[kumaraditya303]

Since generator based coroutines are gone, I think we should relax this check and allow generators.

[JelleZijlstra]

Allowing generators in 3.12 seems like a good idea. It's probably also useful to change the documentation in 3.10 and 3.11 to clarify that generators don't work, as #99936 asked for.

[kumaraditya303]

Let's do it.

[gvanrossum]

So there are two separate tasks here, right:

1. In 3.12, allow generators
2. In the docs for 3.10 and 3.11, explain that generators are not allowed (maybe allude to 3.12 allowing them)

[gvanrossum]

According to GH, the PR will close this issue. But it should remain open until the 3.10/3.11 docs are also updated.

[kumaraditya303]

Fixed by #103748