[New-bugs-announce] [issue27153] Default value shown by argparse.ArgumentDefaultsHelpFormatter is backwards for action='store_false'

[Colin Morris]

New submission from Colin Morris:

Small example:

    import argparse
    parser = argparse.ArgumentParser(formatter_class=argparse.ArgumentDefaultsHelpFormatter)
    parser.add_argument('--no-foo', dest='foo', action='store_false', help="Suppress foo")
    args = parser.parse_args()
    print('foo = {}'.format(args.foo))

Output with "-h":

optional arguments:
  -h, --help  show this help message and exit
  --no-foo    Suppress foo (default: True)

A reasonable person reading that would think that we suppress foo by default. But actually, foo is True by default - "--no-foo" is off by default. I would suggest that if action='store_false', the default value reported by the formatter should be flipped.

----------
components: Library (Lib)
messages: 266602
nosy: Colin Morris
priority: normal
severity: normal
status: open
title: Default value shown by argparse.ArgumentDefaultsHelpFormatter is backwards for action='store_false'
type: behavior
versions: Python 2.7, Python 3.2, Python 3.3, Python 3.4

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue27153>
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