你的第一个装饰器

在上一个例子里，其实我们已经创建了一个装饰器！现在我们修改下上一个装饰器，并编写一个稍微更有用点的程序：

def a_new_decorator(a_func):

    def wrapTheFunction():
        print("I am doing some boring work before executing a_func()")

        a_func()

        print("I am doing some boring work after executing a_func()")

    return wrapTheFunction

def a_function_requiring_decoration():
    print("I am the function which needs some decoration to remove my foul smell")

a_function_requiring_decoration()
#outputs: "I am the function which needs some decoration to remove my foul smell"

a_function_requiring_decoration = a_new_decorator(a_function_requiring_decoration)
#now a_function_requiring_decoration is wrapped by wrapTheFunction()

a_function_requiring_decoration()
#outputs:I am doing some boring work before executing a_func()
#        I am the function which needs some decoration to remove my foul smell
#        I am doing some boring work after executing a_func()

你看明白了吗？我们刚刚应用了之前学习到的原理。这正是python中装饰器做的事情！它们封装一个函数，并且用这样或者那样的方式来修改它的行为。现在你也许疑惑，我们在代码里并没有使用@符号？那只是一个简短的方式来生成一个被装饰的函数。这里是我们如何使用@来运行之前的代码：

@a_new_decorator
def a_function_requiring_decoration():
    """Hey you! Decorate me!"""
    print("I am the function which needs some decoration to "
          "remove my foul smell")

a_function_requiring_decoration()
#outputs: I am doing some boring work before executing a_func()
#         I am the function which needs some decoration to remove my foul smell
#         I am doing some boring work after executing a_func()

#the @a_new_decorator is just a short way of saying:
a_function_requiring_decoration = a_new_decorator(a_function_requiring_decoration)

希望你现在对Python装饰器的工作原理有一个基本的理解。如果我们运行如下代码会存在一个问题：

print(a_function_requiring_decoration.__name__)
# Output: wrapTheFunction