New submission from Martin d'Anjou:
Consider the following code:
#!/usr/bin/env python3
import argparse
# create the top-level parser
parser = argparse.ArgumentParser(prog='PROG')
parser.add_argument('--file', help='A filename', required=True)
subparsers = parser.add_subparsers(help='sub-command help')
# create the parser for the a command
parser_a = subparsers.add_parser('a', help='a help')
parser_a.add_argument('bar', type=int, help='bar help')
# create the parser for the b command
parser_b = subparsers.add_parser('b', help='b help')
parser_b.add_argument('--baz', choices='XYZ', help='baz help')
The help for subparser a is obtained with: parser.parse_args([a,--help])
usage: PROG a [-h] bar
positional arguments:
bar bar help
optional arguments:
-h, --help show this help message and exit
When the user follows the help, the user gets it wrong:
parser.parse_args([a,10])
usage: PROG [-h] --file FILE {a,b} ...
PROG: error: argument --file is required
The correct way to use the subparser is:
parser.parse_args([--file,file,a,10])
But the problem is that the original help message is not telling the user that
this is the correct way. When asking for the a subparser help, the usage
message should also reveal the main parser arguments. Continuing with the
example, something like this should be appropriate:
usage: PROG [-h] --file FILE a [-h] bar
This is how the argparse Java port works.
--
components: Library (Lib)
messages: 208670
nosy: Martin.d'Anjou
priority: normal
severity: normal
status: open
title: argparse subparser usage message hides main parser usage
type: enhancement
versions: Python 3.3
___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue20333
___
___
Python-bugs-list mailing list
Unsubscribe:
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
