[issue9182] argparse: optional argument w/ narg='+' conflicts w/ positional argsument
New submission from Sergey Konoplev gray...@gmail.com:
Hello,
I am starting to use argparse package and faced the problem where an optional
argument w/ nargs='+' conflicts w/ a positional argument.
Here is the test case:
import argparse
p = argparse.ArgumentParser()
p.add_argument('foo', type=str)
_StoreAction(option_strings=[], dest='foo', nargs=None, const=None,
default=None, type=type 'str', choices=None, help=None, metavar=None)
p.add_argument('-b', '--bar', type=int, nargs='+')
_StoreAction(option_strings=['-b', '--bar'], dest='bar', nargs='+', const=None,
default=None, type=type 'int', choices=None, help=None, metavar=None)
p.print_help()
usage: [-h] [-b BAR [BAR ...]] foo
positional arguments:
foo
optional arguments:
-h, --helpshow this help message and exit
-b BAR [BAR ...], --bar BAR [BAR ...]
p.parse_args('-b 123 456 bla'.split())
usage: [-h] [-b BAR [BAR ...]] foo
: error: argument -b/--bar: invalid int value: 'bla'
It prints this usage string usage: [-h] [-b BAR [BAR ...]] foo so it is
assumed that I could use this -b 123 456 bla but it does not works.
How could it be and how to solve it?
Thank you in advance.
--
components: Library (Lib)
messages: 109402
nosy: gray_hemp
priority: normal
severity: normal
status: open
title: argparse: optional argument w/ narg='+' conflicts w/ positional argsument
type: behavior
versions: Python 2.6
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[issue9182] argparse: optional argument w/ narg='+' conflicts w/ positional argsument
Éric Araujo mer...@netwok.org added the comment: Thanks for the bug report. Can you try separating option arguments from positional arguments with “--”? If yes, this would be a doc bug. Also, can you reproduce it with Python 2.7? -- nosy: +merwok ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9182 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9182] argparse: optional argument w/ narg='+' conflicts w/ positional argsument
Eric Smith e...@trueblade.com added the comment:
I get the same behavior in 2.7. Adding '--', I get:
p.parse_args('-b 123 456 -- bla'.split())
Namespace(bar=[123, 456], foo='bla')
Which is what I expect.
Éric: From your comment, I'm not sure if you think it's a doc bug because '--'
does work, or because it doesn't work without it. But I think it's working as
designed. I'm closing this. If you think it's a doc bug, please reopen and
change to the Documentation component.
--
nosy: +eric.smith
resolution: - invalid
status: open - closed
versions: +Python 2.7
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[issue9182] argparse: optional argument w/ narg='+' conflicts w/ positional argsument
Éric Araujo mer...@netwok.org added the comment: I was suggesting a doc bug only if the current doc didn’t advertise clearly this way of combining nargs with positional arguments. Using “--” is most certainly standard and right, Using “--” to explicitly signal positional arguments is most certainly right and standard, but people have to read about that for the first time somewhere. In a perfect world, that would be in their shell’s man page, but better add a word about it in the reference. The “--” marker is actually mentioned in one section: http://docs.python.org/dev/library/argparse#arguments-containing I’m reopening, suggesting that a line be added to explain the standard “--” separator for use cases like Sergey’s. -- assignee: - d...@python components: +Documentation -Library (Lib) nosy: +d...@python resolution: invalid - stage: - needs patch status: closed - open ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9182 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9182] argparse: optional argument w/ narg='+' conflicts w/ positional argsument
Éric Araujo mer...@netwok.org added the comment: Duh, please ignore the first two lines, I forgot to remove them after rephrasing my comment. Sorry. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9182 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue9182] argparse: optional argument w/ narg='+' conflicts w/ positional argsument
Fred L. Drake, Jr. fdr...@acm.org added the comment: On Tue, Jul 6, 2010 at 4:33 PM, Éric Araujo rep...@bugs.python.org wrote: Using “--” to explicitly signal positional arguments is most certainly right and standard, but people have to read about that for the first time somewhere. In a perfect world, that would be in their shell’s man page, but better add a word about it in the reference. It's a convention; not all applications in the larger world support it at all. It needs to be documented for argparse, and also for specific applications (which may or may not be built using argparse or Python. This does not belong in the shell documentation unless needed for the shell itself. -- nosy: +fdrake ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue9182 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
