argparse usage should preserve () in metavars such as range(20)

@iritkatriel

BPO	18349
Nosy	@iritkatriel
Files	metaparen.patch

^{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 2013-07-03.06:16:51.100>
labels = ['type-bug', 'library', '3.9', '3.10', '3.11']
title = 'argparse usage should preserve () in metavars such as range(20)'
updated_at = <Date 2021-12-10.15:48:45.716>
user = 'https://bugs.python.org/paulj3'

bugs.python.org fields:

activity = <Date 2021-12-10.15:48:45.716>
actor = 'iritkatriel'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2013-07-03.06:16:51.100>
creator = 'paul.j3'
dependencies = []
files = ['30754']
hgrepos = []
issue_num = 18349
keywords = ['patch']
message_count = 5.0
messages = ['192222', '192717', '193077', '193188', '408214']
nosy_count = 2.0
nosy_names = ['paul.j3', 'iritkatriel']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue18349'
versions = ['Python 3.9', 'Python 3.10', 'Python 3.11']

As discussed in bpo-16468, a metavar may be used to provide an alternative representation of a choices option. However if a metvar like 'range(20)' is used, usage formatter strips off the '()'.

    >>> parser.add_argument('foo', type=int, 
        choices=range(20), metavar='range(0,20)')
    >>> parser.format_usage()
    # expect: 'usage: PROG [-h] range(0,20)\n'
    # actual: 'usage: PROG [-h] range0,20\n'

This is done by a line in the help formater that removes excess mutually exclusive group notation:

HelpFormatter._format_actions_usage
   ...
   text = _re.sub(r'\(([^|]*)\)', r'\1', text)

A solution is to change this line to distinguish between a case like ' (...)' and 'range(...)'

    text = _re.sub(r'( )\(([^|]*)\)', r'\1\2', text)

I just posted a patch to http://bugs.python.org/issue16468 that uses (and tests) this fix.

This issue should also preserve a metavar like: '(one)two', i.e. '(' at the start.

In http://bugs.python.org/issue10984 these _re replacements are applied to individual action strings as well as the whole usage line. So if () are to be removed from '[-h] (-y)', they should also be removed from '(-y)'.

I just submitted at patch to http://bugs.python.org/issue11874 that takes care of this issue as well.

I rewrote _format_actions_usage() so it formats the parts directly, so there is no need cleanup or parse the full text string.

Reproduced on 3.11:

>>> import argparse
>>> parser = argparse.ArgumentParser()
>>> parser.add_argument('foo', type=int, choices=range(20), metavar='range(0,20)')
_StoreAction(option_strings=[], dest='foo', nargs=None, const=None, default=None, type=<class 'int'>, choices=range(0, 20), help=None, metavar='range(0,20)')
>>> parser.format_usage()
'usage: [-h] range0,20\n'

Simplify argparse usage formatting

gh-62090: Simplify argparse usage formatting (GH-105039)

This was fixed in #102318.

pythongh-62090: Simplify argparse usage formatting (pythonGH-105039)

Navigation Menu

Repository navigation

argparse usage should preserve () in metavars such as range(20) #62549

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

argparse usage should preserve () in metavars such as range(20) #62549

Description

Activity

paulj3 commented on Jul 3, 2013

paulj3 commented on Jul 9, 2013

paulj3 commented on Jul 15, 2013

paulj3 commented on Jul 16, 2013

iritkatriel commented on Dec 10, 2021

encukou commented on May 7, 2024

Metadata

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Issue actions