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我们什么时候调用实际上的decorator中的内部函数?

decorator python

0

alekscooper · 技术社区 · 6 年前

我正在努力理解Python中的比较器,其中一个教程建议查看以下示例:

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

def say_whee():
    print("Whee!")

say_whee = my_decorator(say_whee)

say_whee()

当我呼唤 say_whee() 它打印以下内容:

Something is happening before the function is called.
Whee!
Something is happening after the function is called.

我模糊地理解为什么它会打印这些行,但我不明白我们什么时候打电话 wrapper() 所以它可以打印这些线条。

我们什么时候打电话 包装件() ?

1 回复 | 直到 6 年前

1

juanpa.arrivillaga 6 年前

你 返回 wrapper 并分配给 say_wee :

say_whee = my_decorator(say_whee)

所以这里叫:

say_whee()

自己看看:

>>> def my_decorator(func):
...     def wrapper():
...         print("Something is happening before the function is called.")
...         func()
...         print("Something is happening after the function is called.")
...     return wrapper
...
>>> def say_whee():
...     print("Whee!")
...
>>> say_whee = my_decorator(say_whee)
>>>
>>> say_whee
<function my_decorator.<locals>.wrapper at 0x1040d89d8>
>>> say_whee.__name__
'wrapper'