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copied!<p>I'm a little unclear about what you need, but may be this outline of what happens when you create subparsers will help.</p> <pre><code>p=argparse.ArgumentParser() In [3]: sp=p.add_subparsers() In [4]: sp Out[4]: _SubParsersAction(option_strings=[], dest='==SUPPRESS==', nargs='A...', const=None, default=None, type=None, choices=OrderedDict(), help=None, metavar=None) In [5]: sp._parser_class Out[5]: argparse.ArgumentParser In [7]: spp=sp.add_parser('cmd') In [8]: spp Out[8]: ArgumentParser(prog='ipython cmd', usage=None, description=None, version=None, formatter_class=<class 'argparse.HelpFormatter'>, conflict_handler='error',add_help=True) </code></pre> <p><code>sp</code> is a positional <code>Action</code> that takes <code>choices</code> (the subparser names). It has a <code>hidden</code> attribute <code>_parser_class</code> that is the class that it uses to create the new subparsers.</p> <p><a href="https://stackoverflow.com/questions/20165843/argparse-how-to-handle-variable-number-of-arguments-nargs/20167038#20167038">Argparse: how to handle variable number of arguments (nargs='*')</a> raises the possibility of changing that <code>_parser_class</code> to produce different behavior in the subparsers. <a href="http://bugs.python.org/issue17204" rel="nofollow noreferrer">http://bugs.python.org/issue17204</a> is a related bug issue. </p> <p>If the subparser just needs an extra method (or a customized version of an existing one), there are a couple of ways to do it:</p> <ul> <li>subclass <code>ArgumentParser</code> and use the subclass for the parser (works if the parser does not use the new method).</li> <li>use the above discussion to create a subparser with the new class</li> <li>add the new method to the subparser object itself. </li> </ul> <p>Threads like <a href="https://stackoverflow.com/questions/962962/python-changing-methods-and-attributes-at-runtime">Python: changing methods and attributes at runtime</a> discuss the ins and outs of changing the methods of an instance.</p>

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