Class CommandParsers

cmd2/cmd2.py:232–303

Create and store all command method argument parsers for a given Cmd instance. Parser creation and retrieval are accomplished through the get() method.

class CommandParsers:
    """Create and store all command method argument parsers for a given Cmd instance.

    Parser creation and retrieval are accomplished through the get() method.
    """

    def __init__(self, cmd: "Cmd") -> None:
        """Initialize CommandParsers.

        :param cmd: the Cmd instance whose parsers are being managed
        """
        self._cmd = cmd

        # Keyed by the fully qualified method names. This is more reliable than
        # the methods themselves, since wrapping a method will change its address.
        self._parsers: dict[str, Cmd2ArgumentParser] = {}

    @staticmethod
    def _fully_qualified_name(command_method: BoundCommandFunc) -> str:
        """Return the fully qualified name of a method or None if a method wasn't passed in."""
        try:
            return f"{command_method.__module__}.{command_method.__qualname__}"
        except AttributeError:
            return ""

    def __contains__(self, command_method: BoundCommandFunc) -> bool:
        """Return whether a given method's parser is in self.

        If the parser does not yet exist, it will be created if applicable.
        This is basically for checking if a method is argarse-based.
        """
        parser = self.get(command_method)
        return bool(parser)

    def get(self, command_method: BoundCommandFunc) -> Cmd2ArgumentParser | None:
        """Return a given method's parser or None if the method is not argparse-based.

        If the parser does not yet exist, it will be created.
        """
        full_method_name = self._fully_qualified_name(command_method)
        if not full_method_name:
            return None

        if full_method_name not in self._parsers:
            if not command_method.__name__.startswith(COMMAND_FUNC_PREFIX):
                return None
            command = command_method.__name__[len(COMMAND_FUNC_PREFIX) :]

            parser_builder = getattr(command_method, constants.CMD_ATTR_ARGPARSER, None)
            if parser_builder is None:
                return None

            parent = self._cmd.find_commandset_for_command(command) or self._cmd
            parser = self._cmd._build_parser(parent, parser_builder)

            # To ensure accurate usage strings, recursively update 'prog' values
            # within the parser to match the command name.
            parser.update_prog(command)