def returns()

in mujoco_worldgen/util/types.py [0:0]

• 27 lines of code
• 7 McCabe index (conditional complexity)

def returns(*accepted_return_type_tuple):
    '''
    Validates the return type. Since there's only ever one
    return type, this makes life simpler. Along with the
    accepts() decorator, this also only does a check for
    the top argument. For example you couldn't check
    (<type 'tuple'>, <type 'int'>, <type 'str'>).
    In that case you could only check if it was a tuple.

    See also maybe() for optionally returning a type or None
    '''

    def return_decorator(validate_function):
        ''' Do not call this function directly!  Use @returns(...) instead ! '''
        # No return type has been specified.
        if len(accepted_return_type_tuple) == 0:
            raise TypeError('You must specify a return type.')

        @functools.wraps(validate_function)
        def decorator_wrapper(*function_args, **function_args_dict):
            # More than one return type has been specified.
            if len(accepted_return_type_tuple) > 1:
                raise TypeError('You must specify one return type.')

            # Since the decorator receives a tuple of arguments
            # and the is only ever one object returned, we'll just
            # grab the first parameter.
            accepted_return_type = accepted_return_type_tuple[0]

            # We'll execute the function, and
            # take a look at the return type.
            return_value = validate_function(*function_args, **function_args_dict)
            return_value_type = type(return_value)

            if isinstance(return_value_type, accepted_return_type):
                raise InvalidReturnType(return_value_type,
                                        validate_function.__name__)

            return return_value

        return decorator_wrapper

    return return_decorator