Method _validate_prepostloop_callable

cmd2/cmd2.py:5823–5829

Check parameter and return types for preloop and postloop hooks.

(cls, func: Callable[[], None])

    @classmethod
    def _validate_prepostloop_callable(cls, func: Callable[[], None]) -> None:
        """Check parameter and return types for preloop and postloop hooks."""
        cls._validate_callable_param_count(func, 0)
        # make sure there is no return annotation or the return is specified as None
        _, ret_ann = get_types(func)
        if ret_ann is not None:
            raise TypeError(f"{func.__name__} must have a return type of 'None', got: {ret_ann}")

    def register_preloop_hook(self, func: Callable[[], None]) -> None:
        """Register a function to be called at the beginning of the command loop."""