Type checking decorator - a simple Python decorator for validating the type of passed arguments for functions and methods

type_checker.py

# Works with builtin types and classes. Does not support type checking with annotations.
# If you are using types composed with the `typing` module, a more advanced validator should be used
def assert_type(*typed_args, **typed_kwargs):
    """Check the type of args and kwargs passed to a function/method."""

    def decorator(func: Callable):
        sig = inspect.signature(func)
        bound_types = sig.bind_partial(*typed_args, **typed_kwargs).arguments

        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            bound_values = sig.bind(*args, **kwargs).arguments
            for name in bound_types.keys() & bound_values.keys():
                if not isinstance(bound_values[name], bound_types[name]):
                    raise TypeError(f"{bound_values[name]} is not {bound_types[name]}.")

            return func(*args, **kwargs)

        return wrapper

    return decorator