Method add_subparsers

Lib/argparse.py:2026–2061

(self, **kwargs)

    # ==================================

    def add_subparsers(self, **kwargs):
        if self._subparsers is not None:
            raise ValueError('cannot have multiple subparser arguments')

        # add the parser class to the arguments if it's not present
        kwargs.setdefault('parser_class', type(self))

        if 'title' in kwargs or 'description' in kwargs:
            title = kwargs.pop('title', _('subcommands'))
            description = kwargs.pop('description', None)
            self._subparsers = self.add_argument_group(title, description)
        else:
            self._subparsers = self._positionals

        # prog defaults to the usage message of this parser, skipping
        # non-required optional arguments and with no "usage:" prefix
        if kwargs.get('prog') is None:
            # Create formatter without color to avoid storing ANSI codes in prog
            formatter = self.formatter_class(prog=self.prog)
            formatter._set_color(False)
            positionals = self._get_positional_actions()
            required_optionals = [action for action in self._get_optional_actions()
                                  if action.required]
            groups = self._mutually_exclusive_groups
            formatter.add_usage(None, required_optionals + positionals, groups, '')
            kwargs['prog'] = formatter.format_help().strip()

        # create the parsers action and add it to the positionals list
        parsers_class = self._pop_action_class(kwargs, 'parsers')
        action = parsers_class(option_strings=[], **kwargs)
        action._color = self.color
        self._check_help(action)
        self._subparsers._add_action(action)

        # return the created parsers action
        return action

    def _add_action(self, action):
        if action.option_strings: