New submission from Steven Bethard <[email protected]>:
[Moved from http://code.google.com/p/argparse/issues/detail?id=73]
What steps will reproduce the problem?
parser = ArgumentParser(prefix_chars="-+")
parser.add_argument("-a",action="store_true")
parser.add_argument("+b",action="store_true")
parser.add_argument("+c",action="store_true")
print parser.parse_args("-abc".split())
What is the expected output? What do you see instead?
I would expect Namespace(a=True, b=True, c=True)
You get Namespace(a=True, b=False, c=True)
because in the loop that iterates through the prefix characters it builds an
option_string to try by pulling the first character off explicit_arg. If it
doesn't match any option then it will try the next prefix character, but it
will have lost that character from the explicit_arg. This is also a problem
even with only one prefix character because if it doesn't match an option the
error message will be missing that one character.
The above match -a, tried -b and fails, but instead of trying +b, it tries +c
because the b has been lost.
I've included multiple_short.patch which fixes just this bug. However, I also
don't agree with the behavior of trying all prefix characters. I would expect
that when merging short options together they would have to all share the same
prefix character. If I have prefix_chars="-+" and I have options -a, +a, -b,
and +b and I type +ab I would expect my action to be called with option_strings
+a and +b, not +a and -b. The patch to fix the above bug *and* only try the
same prefix character as the first option is multiple_short_same_prefix.patch.
[Only the latter patch (which sounds like the right behavior) is attached. It
will need to be updated to work against Python trunk.]
----------
components: Library (Lib)
files: multiple_short_same_prefix.patch
keywords: patch
messages: 111328
nosy: bethard
priority: normal
severity: normal
stage: needs patch
status: open
title: argparse eats characters when parsing multiple merged short options
type: behavior
versions: Python 2.7, Python 3.2
Added file: http://bugs.python.org/file18147/multiple_short_same_prefix.patch
_______________________________________
Python tracker <[email protected]>
<http://bugs.python.org/issue9352>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
