PEP 570: Python Positional-Only Parameters

[pablogsal]

BPO	36540
Nosy	@vstinner, @ericvw, @ambv, @serhiy-storchaka, @willingc, @pablogsal, @gousaiyang
PRs	bpo-36540: PEP 570 -- Implementation #12701 bpo-36540 What's New section for PEP 570 #12942 bpo-36540: Documentation for PEP570 - Python positional only arguments #13202 bpo-36540: Document changes for PyCode_New regarding PEP570 #13706 bpo-36540: Improve doc of function definition regarding positional-only arguments #25235 [3.9] bpo-36540: Improve doc of function definition regarding positional-only arguments (GH-25235) #25259 [3.8] bpo-36540: Improve doc of function definition regarding positional-only arguments (GH-25235) #25260

^{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 = 'https://github.com/pablogsal'
closed_at = <Date 2019-05-28.23:49:45.310>
created_at = <Date 2019-04-06.01:06:03.833>
labels = ['interpreter-core', '3.8']
title = 'PEP 570: Python Positional-Only Parameters'
updated_at = <Date 2021-04-07.19:32:56.057>
user = 'https://github.com/pablogsal'

bugs.python.org fields:

activity = <Date 2021-04-07.19:32:56.057>
actor = 'pablogsal'
assignee = 'pablogsal'
closed = True
closed_date = <Date 2019-05-28.23:49:45.310>
closer = 'pablogsal'
components = ['Interpreter Core']
creation = <Date 2019-04-06.01:06:03.833>
creator = 'pablogsal'
dependencies = []
files = []
hgrepos = []
issue_num = 36540
keywords = ['patch']
message_count = 14.0
messages = ['339521', '340141', '340246', '340247', '341041', '341071', '341072', '341073', '341119', '343835', '343836', '390467', '390470', '390471']
nosy_count = 7.0
nosy_names = ['vstinner', 'ericvw', 'lukasz.langa', 'serhiy.storchaka', 'willingc', 'pablogsal', 'gousaiyang']
pr_nums = ['12701', '12942', '13202', '13706', '25235', '25259', '25260']
priority = 'high'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue36540'
versions = ['Python 3.8']

[pablogsal]

This issue will serve to track development and PRs for the implementation of PEP-570: Python Positional-Only Parameters.

[pablogsal]

I will separate the work in two Pull Request (maybe more). The implementation of the PEP will be done in PR12701 and the documentation and other additions will be done in future Pull Requests to keep things more manageable.

[serhiy-storchaka]

PR 12701 makes breaking changes in the inspect module.

Currently we have two sets of APIs in the inspect module: old deprecated API that do not support keyword-only arguments, and new *full* API that supports them. Even many years since 3.0 the old API still has not been removed. Adding support for positional-only arguments needs changes of the same order as adding support of keyword-only arguments. It means deprecating the current API and introducing a new (fuller?) API. This is a slow process for many releases. We could also take opportunity to redesign APIs completely instead of just adding new parameters and fields.

I suggest to remove all breaking changes in the inspect module and defer them to the separate issue. This perhaps will need a discussion on Python-Dev, and maybe not one.

[vstinner]

It seems like deprecating or removing "old" inspect functions is an issue. An option would be to raise an error if these functions is used on a function which has at least one positional argument.

[pablogsal]

Łukasz, are you ok if we include this one in alpha4 as we were discussing in the PRs? If you are happy with that I will merge it so there is early testing and then we can keep working on the documentation and minor details for the next stage. If not, please, unmark it as a release blocker.

[pablogsal]

Opened https://bugs.python.org/issue36751 to track changes in the inspect module.

[pablogsal]

New changeset 8c77b8c by Pablo Galindo in branch 'master':
bpo-36540: PEP-570 -- Implementation (GH-12701)
8c77b8c

[pablogsal]

The implementation has been merged, so I will remove the "release blocker". We are still missing the documentation and the final changes to the inspect module.

[ambv]

+1

[willingc]

New changeset b76302d by Carol Willing (Pablo Galindo) in branch 'master':
bpo-36540: Documentation for PEP-570 - Python positional only arguments (bpo-13202)
b76302d

[pablogsal]

Closing this. Will reopen if we realize we missed something.

[pablogsal]

New changeset 58d72ca by Saiyang Gou in branch 'master':
bpo-36540: Improve doc of function definition regarding positional-only arguments (GH-25235)
58d72ca

[pablogsal]

New changeset 4554ab4 by Saiyang Gou in branch '3.8':
[3.8] bpo-36540: Improve doc of function definition regarding positional-only arguments (GH-25235) (GH-25260)
4554ab4

[pablogsal]

New changeset 3b1cf20 by Saiyang Gou in branch '3.9':
[3.9] bpo-36540: Improve doc of function definition regarding positional-only arguments (GH-25235) (GH-25259)
3b1cf20