argparse ConfigureAction problem

Sat Mar 24 14:30:09 EDT 2012

I've been using arparse with ConfigureAction (which is shown below). But, it 
doesn't play well with positional arguments. For example:
./plot_stuff2.py --plot stuff1 stuff2
[...]
plot_stuff2.py: error: argument --plot/--with-plot/--enable-plot/--no-plot/--
without-plot/--disable-plot: invalid boolean value: 'stuff1'
Problem is --plot takes an optional argument, and so the positional arg is 
assumed to be the arg to --plot. Not sure how to fix this.
Here is the parser code:
 parser = argparse.ArgumentParser()
[...]
 parser.add_argument ('--plot', action=ConfigureAction, default=False)
 parser.add_argument ('files', nargs='*')

 opt = parser.parse_args(cmdline[1:])
Here is ConfigureAction:
-----------------------------------------------------
import argparse
import re
def boolean(string):
 string = string.lower()
 if string in ['0', 'f', 'false', 'no', 'off']:
 return False
 elif string in ['1', 't', 'true', 'yes', 'on']:
 return True
 else:
 raise ValueError()
class ConfigureAction(argparse.Action):
 def __init__(self,
 option_strings,
 dest,
 default=None,
 required=False,
 help=None,
 metavar=None,
 positive_prefixes=['--', '--with-', '--enable-'],
 negative_prefixes=['--no-', '--without-', '--disable-']):
 strings = []
 self.positive_strings = set()
 self.negative_strings = set()
 for string in option_strings:
 assert re.match(r'--[A-z]+', string)
 suffix = string[2:]
 for positive_prefix in positive_prefixes:
 self.positive_strings.add(positive_prefix + suffix)
 strings.append(positive_prefix + suffix)
 for negative_prefix in negative_prefixes:
 self.negative_strings.add(negative_prefix + suffix)
 strings.append(negative_prefix + suffix)
 super(ConfigureAction, self).__init__(
 option_strings=strings,
 dest=dest,
 nargs='?',
 const=None,
 default=default,
 type=boolean,
 choices=None,
 required=required,
 help=help,
 metavar=metavar)
 def __call__(self, parser, namespace, value, option_string=None):
 if value is None:
 value = option_string in self.positive_strings
 elif option_string in self.negative_strings:
 value = not value
 setattr(namespace, self.dest, value)