python: enforcing type check on function using decorator

 

  def typeassert(*ty_args, **ty_kwargs):
        """
        利用装饰器对函数参数强制性类型检查
        enforcing type check on function using decorator
        :param ty_args:
        :param ty_kwargs:
        :return:
        """
        def decorate(func):
            # If in optimized mode, disable type checking
            if not __debug__:
                return func

            # Map function argument names to supplied types
            sig = signature(func)
            bound_types = sig.bind_partial(*ty_args, **ty_kwargs).arguments

            @wraps(func)
            def wrapper(*args, **kwargs):
                bound_values = sig.bind(*args, **kwargs)
                # Enforce type assertions across supplied arguments
                for name, value in bound_values.arguments.items():
                    if name in bound_types:
                        if not isinstance(value, bound_types[name]):
                            raise TypeError(
                                'Argument {} must be {}'.format(name, bound_types[name])
                            )
                return func(*args, **kwargs)

            return wrapper

        return decorate

    @typeassert(int, z=int)
    def spam(x, y, z=42):
        """

        :param y:
        :param z:
        :return:
        """
        print(x, y, z)

#https://github.com/yidao620c/python3-cookbook/blob/master/source/c09/p07_enforcing_type_check_on_function_using_decorator.rst