Function register_argparse_argument_parameter

cmd2/argparse_utils.py:296–345

Register a custom parameter for argparse.Action and add accessors to the Action class. :param param_name: Name of the parameter. This must be a valid Python identifier. :param validator: Optional function to validate and/or transform the parameter value. It accepts the

(
    param_name: str,
    *,
    validator: Callable[[argparse.Action, Any], Any] | None = None,
)

def register_argparse_argument_parameter(
    param_name: str,
    *,
    validator: Callable[[argparse.Action, Any], Any] | None = None,
) -> None:
    """Register a custom parameter for argparse.Action and add accessors to the Action class.

    :param param_name: Name of the parameter. This must be a valid Python identifier.
    :param validator: Optional function to validate and/or transform the parameter value.
                      It accepts the Action instance and the value as arguments.
    :raises ValueError: if the parameter name is invalid
    :raises KeyError: if the new parameter collides with any existing attributes
    """
    if not param_name.isidentifier():
        raise ValueError(f"Invalid parameter name '{param_name}': must be a valid Python identifier")

    if param_name in _CUSTOM_ACTION_ATTRIBS:
        raise KeyError(f"Custom parameter '{param_name}' is already registered")

    # Ensure we don't hijack standard argparse.Action attributes or existing methods
    if hasattr(argparse.Action, param_name):
        raise KeyError(f"'{param_name}' conflicts with an existing attribute on argparse.Action")

    # Check if accessors already exist (e.g., from manual patching or previous registration)
    getter_name = f"get_{param_name}"
    setter_name = f"set_{param_name}"
    if hasattr(argparse.Action, getter_name) or hasattr(argparse.Action, setter_name):
        raise KeyError(f"Accessor methods for '{param_name}' already exist on argparse.Action")

    # Check for the prefixed internal attribute name collision (e.g., _cmd2_<param_name>)
    attr_name = constants.cmd2_private_attr_name(param_name)
    if hasattr(argparse.Action, attr_name):
        raise KeyError(f"The internal attribute '{attr_name}' already exists on argparse.Action")

    def _action_get_custom_parameter(self: argparse.Action) -> Any:
        """Get the custom attribute of an argparse Action."""
        return getattr(self, attr_name, None)

    setattr(argparse.Action, getter_name, _action_get_custom_parameter)

    def _action_set_custom_parameter(self: argparse.Action, value: Any) -> None:
        """Set the custom attribute of an argparse Action."""
        if validator is not None:
            value = validator(self, value)

        setattr(self, attr_name, value)

    setattr(argparse.Action, setter_name, _action_set_custom_parameter)

    _CUSTOM_ACTION_ATTRIBS.add(param_name)


def _validate_completion_callable(self: argparse.Action, value: Any) -> Any: