Question

As mentioned in the docs the optparse.OptionParser uses an IndentedHelpFormatter to output the formatted option help, for which which I found some API documentation.

I want to display a similarly formatted help text for the required, positional arguments in the usage text. Is there an adapter or a simple usage pattern that can be used for similar positional argument formatting?

Clarification

Preferably only using the stdlib. Optparse does great except for this one formatting nuance, which I feel like we should be able to fix without importing whole other packages. 🙂

Answer 1

The best bet would be to write a patch to the optparse module. In the meantime, you can accomplish this with a slightly modified OptionParser class. This isn’t perfect, but it’ll get what you want done.

#!/usr/bin/env python from optparse import OptionParser, Option, IndentedHelpFormatter  class PosOptionParser(OptionParser):     def format_help(self, formatter=None):         class Positional(object):             def __init__(self, args):                 self.option_groups = []                 self.option_list = args          positional = Positional(self.positional)         formatter = IndentedHelpFormatter()         formatter.store_option_strings(positional)         output = ['\n', formatter.format_heading('Positional Arguments')]         formatter.indent()         pos_help = [formatter.format_option(opt) for opt in self.positional]         pos_help = [line.replace('--','') for line in pos_help]         output += pos_help         return OptionParser.format_help(self, formatter) + ''.join(output)      def add_positional_argument(self, option):         try:             args = self.positional         except AttributeError:             args = []         args.append(option)         self.positional = args      def set_out(self, out):         self.out = out def main():     usage = 'usage: %prog [options] bar baz'     parser = PosOptionParser(usage)     parser.add_option('-f', '--foo', dest='foo',                       help='Enable foo')     parser.add_positional_argument(Option('--bar', action='store_true',                                    help='The bar positional argument'))     parser.add_positional_argument(Option('--baz', action='store_true',                                    help='The baz positional argument'))     (options, args) = parser.parse_args()     if len(args) != 2:         parser.error('incorrect number of arguments')     pass  if __name__ == '__main__':     main() 

And the output you get from running this:

Usage: test.py [options] bar baz    Options:     -h, --help         show this help message and exit     -f FOO, --foo=FOO  Enable foo  Positional Arguments:   bar  The bar positional argument   baz  The baz positional argument