asyncio is not inspecting keyword arguments of functools.partial

[iceb0y]

BPO	26654
Nosy	@gvanrossum, @vstinner, @1st1, @iceb0y
PRs	[Do Not Merge] Convert Misc/NEWS so that it is managed by towncrier #552

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

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GitHub fields:

assignee = None
closed_at = <Date 2016-09-15.20:02:53.258>
created_at = <Date 2016-03-28.09:57:30.060>
labels = ['expert-asyncio']
title = 'asyncio is not inspecting keyword arguments of functools.partial'
updated_at = <Date 2017-03-31.16:36:35.834>
user = 'https://github.com/iceb0y'

bugs.python.org fields:

activity = <Date 2017-03-31.16:36:35.834>
actor = 'dstufft'
assignee = 'none'
closed = True
closed_date = <Date 2016-09-15.20:02:53.258>
closer = 'yselivanov'
components = ['asyncio']
creation = <Date 2016-03-28.09:57:30.060>
creator = 'iceboy'
dependencies = []
files = []
hgrepos = []
issue_num = 26654
keywords = []
message_count = 6.0
messages = ['262566', '262588', '262608', '262631', '276610', '276611']
nosy_count = 5.0
nosy_names = ['gvanrossum', 'vstinner', 'python-dev', 'yselivanov', 'iceboy']
pr_nums = ['552']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue26654'
versions = ['Python 3.5']

[iceb0y]

import asyncio
import functools

def foo(x): raise Exception()

loop = asyncio.get_event_loop()
loop.call_soon(functools.partial(foo, x=1))
loop.run_forever()

Current error message:
Exception in callback foo()() at ...:4

Expected error message:
Exception in callback foo(x=1)() at ...:4

[gvanrossum]

Oh, wow. I didn't even know we special-case partial() there. In general we tend to focus more on positional arguments (since asyncio intentionally doesn't take keyword args for callbacks) but I see no reason why we couldn't add this here. Maybe you're interested in writing a patch yourself? You could do it as a PR for the "upstream" git repo https://github.com/python/asyncio

[iceb0y]

Created a PR python/asyncio#328. Please review. Thanks.

[vstinner]

Oh, wow. I didn't even know we special-case partial() there.

I wrote the code doing that. I did it to get more readable and shorter logs since asyncio produces a lot of logs.

Example:

Exception in callback print("Hello", "World!")() at ...:4

without special case:

Exception in functools.partial(<built-in function print>, 'Hello', 'World!') at ...:4

[python-dev]

New changeset 4ab64ea31d75 by Yury Selivanov in branch '3.5':
Issue bpo-26654: Inspect functools.partial in asyncio.Handle.__repr__.
https://hg.python.org/cpython/rev/4ab64ea31d75

New changeset 03257f04ee9f by Yury Selivanov in branch '3.6':
Merge 3.5 (issue bpo-26654)
https://hg.python.org/cpython/rev/03257f04ee9f

New changeset 1dbe3addba28 by Yury Selivanov in branch 'default':
Merge 3.6 (issue bpo-26654)
https://hg.python.org/cpython/rev/1dbe3addba28

[1st1]

Merged! Thank you!