optparse option prefix

[Steven Bethard]

Mathias Waack wrote:
> We've integrated python into a legacy application. Everything works fine (of
> course because its python;). There's only one small problem: the
> application reads the commandline and consumes all arguments prefixed with
> a '-' sign. Thus its not possible to call a python module from the
> commandline with a parameter list containing options prefixed by '-'
> or '--' signs. Thats not a major problem, but it prevents us from using th
> optparse module. Is there a way to change to prefix, so one could use a '+'
> (for instance) to mark command line options for optparse?

If your arguments come in a particular order, you could use argparse 
(http://argparse.python-hosting.com/) to parse them as positional 
arguments::

     >>> parser = argparse.ArgumentParser()
     >>> parser.add_argument('foo')
     >>> parser.add_argument('bar', nargs='+')
     >>> parser.add_argument('baz')
     >>> parser.parse_args('FOO BAR1 BAR2 BAR3 BAZ'.split())
     Namespace(bar=['BAR1', 'BAR2', 'BAR3'], baz='BAZ', foo='FOO')

I've also filed a feature request for you asking for options with '+' as 
a prefix:

     http://argparse.python-hosting.com/ticket/30

I'll see if I can make some time to implement it, but if you'd like to 
take a look yourself, I can see '-' being hard-coded in at least:

     add_argument()
     _get_optional_kwargs()
     consume_optional() within _parse_args()
     _parse_optional()
     _get_option_prefix_tuples()

I guess there ought to be an easy way to customize the prefix 
characters...  Maybe something like::

     parser = argparse.ArgumentParser(prefix_chars='+')

STeVe