Python简单装饰问题

Question

def my_decorator(some_function):
        print("Something is happening before some_function() is called.")
        some_function()
        print("Something is happening after some_function() is called.")

def just_some_function():
    print("Wheee!")

just_some_function = my_decorator(just_some_function)
just_some_function()

TypeError: 'NoneType' object is not callable 

我真的不明白，为什么这个不起作用？

根据我的理解，just_some_function基本上应该变成这样：

just_some_function():
        print("Something is happening before some_function() is called.")  
        print("Wheee!")  
        print("Something is happening after some_function() is called.")  

但是，原始函数需要一个包装函数才能工作，例如：

def my_decorator(some_function):
    def wrapper():
        print("Something is happening before some_function() is called.")
        some_function()
        print("Something is happening after some_function() is called.")
    return wrapper

为什么？谁能解释一下背后的逻辑吗？

Answer 1

装饰师应该创建“替换”原有功能的新功能。

def my_decorator(some_function):
        print("Something is happening before some_function() is called.")
        some_function()
        print("Something is happening after some_function() is called.")

这个“装饰器”返回None -> just_some_function = None -> TypeError：'NoneType‘对象不可调用

def my_decorator(some_function):
    def wrapper():
        print("Something is happening before some_function() is called.")
        some_function()
        print("Something is happening after some_function() is called.")
    return wrapper

这个“装饰器”返回包装器-> just_some_function =包装器-> --它正在工作。

你也可以检查。试试print(just_some_function.__name__) ->的“包装器”。