Python简单装饰器问题

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，为什么这不起作用？

根据我的理解，just_some_function 基本上应该是这样的：

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？有人能解释一下它背后的逻辑吗？

Answer 1

装饰者应该创建“替换”原始功能的新功能。

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' object is not callable

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 = wrapper -> 它的工作。

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