Method _validate_prepostcmd_hook

cmd2/cmd2.py:5862–5880

Check parameter and return types for pre and post command hooks.

(
        cls, func: Callable[[CommandDataType], CommandDataType], data_type: type[CommandDataType]
    )

    @classmethod
    def _validate_prepostcmd_hook(
        cls, func: Callable[[CommandDataType], CommandDataType], data_type: type[CommandDataType]
    ) -> None:
        """Check parameter and return types for pre and post command hooks."""
        # validate that the callable has the right number of parameters
        cls._validate_callable_param_count(cast(Callable[..., Any], func), 1)

        type_hints, ret_ann = get_types(func)
        if not type_hints:
            raise TypeError(f"{func.__name__} parameter is missing a type hint, expected: {data_type}")
        _param_name, par_ann = next(iter(type_hints.items()))
        # validate the parameter has the right annotation
        if par_ann != data_type:
            raise TypeError(f"argument 1 of {func.__name__} has incompatible type {par_ann}, expected {data_type}")
        # validate the return value has the right annotation
        if ret_ann is None:
            raise TypeError(f"{func.__name__} does not have a declared return type, expected {data_type}")
        if ret_ann != data_type:
            raise TypeError(f"{func.__name__} has incompatible return type {ret_ann}, expected {data_type}")

    def register_precmd_hook(self, func: Callable[[plugin.PrecommandData], plugin.PrecommandData]) -> None:
        """Register a hook to be called before the command function."""