#!/usr/bin/env python
     # encoding: utf-8
     #
     # Copyright (c) 2010 Doug Hellmann.  All rights reserved.
     #
     """Defining custom action callbacks
     """
     #end_pymotw_header
     
     import argparse
     
     class CustomAction(argparse.Action):
         def __init__(self,
                      option_strings,
                      dest,
                      nargs=None,
                      const=None,
                      default=None,
                      type=None,
                      choices=None,
                      required=False,
                      help=None,
                      metavar=None):
             argparse.Action.__init__(self,
                                      option_strings=option_strings,
                                      dest=dest,
                                      nargs=nargs,
                                      const=const,
                                      default=default,
                                      type=type,
                                      choices=choices,
                                      required=required,
                                      help=help,
                                      metavar=metavar,
                                      )
             print
             print 'Initializing CustomAction'
             for name,value in sorted(locals().items()):
                 if name == 'self' or value is None:
                     continue
                 print '  %s = %r' % (name, value)
             return
     
         def __call__(self, parser, namespace, values, option_string=None):
             print
             print 'Processing CustomAction for "%s"' % self.dest
             print '  parser = %s' % id(parser)
             print '  values = %r' % values
             print '  option_string = %r' % option_string
             
             # Do some arbitrary processing of the input values
             if isinstance(values, list):
                 values = [ v.upper() for v in values ]
             else:
                 values = values.upper()
             # Save the results in the namespace using the destination
             # variable given to our constructor.
             setattr(namespace, self.dest, values)
     
     parser = argparse.ArgumentParser()
     
     parser.add_argument('-a', action=CustomAction)
     parser.add_argument('-m', nargs='*', action=CustomAction)
     parser.add_argument('positional', action=CustomAction)
     
     results = parser.parse_args(['-a', 'value', '-m' 'multi-value', 'positional-value'])
     print
     print results