[New-bugs-announce] [issue23795] argparse -- incorrect usage for mutually exclusive

João Ferreira report at bugs.python.org
Fri Mar 27 19:02:33 CET 2015

New submission from João Ferreira:

The usage that is printed by argparse with the "--help" argument is slightly incorrect when using mutually exclusive groups. This happens in version 3.4.3 but did not happen in version 3.4.0.

I have this minimal example:

import argparse

p = argparse.ArgumentParser()

g1 = p.add_mutually_exclusive_group(required=False)

g2 = p.add_mutually_exclusive_group(required=False)


In python 3.4.0, "python test.py --help" produces the usage:

usage: test.py [-h] [-a A | -b B] [-c C | -d D]

In python 3.4.3, the usage is:

usage: test.py [-h] [-a A | -b B [-c C | -d D]

Note the absence of the closing square bracket after B.

components: Library (Lib)
messages: 239425
nosy: jotomicron
priority: normal
severity: normal
status: open
title: argparse -- incorrect usage for mutually exclusive
type: enhancement
versions: Python 3.4

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