Support functools.partial in inspect.is*function() checks

[asvetlov]

BPO	34890
Nosy	@asvetlov, @1st1, @pablogsal, @sweeneyde
PRs	bpo-34890: Make iscoroutinefunction, isgeneratorfunction and isasyncgenfunction work with functools.partial #9903

^{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 2018-10-26.11:23:04.921>
created_at = <Date 2018-10-04.07:29:56.296>
labels = ['3.8', 'library']
title = 'Support functools.partial in inspect.is*function() checks'
updated_at = <Date 2022-02-13.06:36:40.836>
user = 'https://github.com/asvetlov'

bugs.python.org fields:

activity = <Date 2022-02-13.06:36:40.836>
actor = 'Dennis Sweeney'
assignee = 'none'
closed = True
closed_date = <Date 2018-10-26.11:23:04.921>
closer = 'pablogsal'
components = ['Library (Lib)']
creation = <Date 2018-10-04.07:29:56.296>
creator = 'asvetlov'
dependencies = []
files = []
hgrepos = []
issue_num = 34890
keywords = ['patch']
message_count = 5.0
messages = ['327039', '327056', '327057', '328538', '413171']
nosy_count = 4.0
nosy_names = ['asvetlov', 'yselivanov', 'pablogsal', 'Dennis Sweeney']
pr_nums = ['9903']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue34890'
versions = ['Python 3.8']

[asvetlov]

isfunction() processes both isfunction(func) and isfunction(partial(func, arg)) correctly.

But iscoroutinefunction() misses this functionality.

We can implement it easy by adding a check for isinstance(func, partial) and applying a coroutine check for func.func.

Also, we can do the same for isgeneratorfunction() and isasyncgenfunction().

The patch looks easy and straightforward.

Yuri, what do you think about?

[1st1]

I think the fact that inspect.isfunction recognizes partials is a very strong argument to enable inspect.iscoroutinefunction to do so as well.

This is a backwards incompatible change though, strictly speaking.

[1st1]

Feel free to work on the PR. If we want to push this to 3.8 we should do that now and have enough time for it to be tested.

[pablogsal]

New changeset 7cd2543 by Pablo Galindo in branch 'master':
bpo-34890: Make iscoroutinefunction, isgeneratorfunction and isasyncgenfunction work with functools.partial (GH-9903)
7cd2543

[sweeneyde]

See https://bugs.python.org/issue46722 for a concern about this change.