装饰器类和装饰器函数之间的区别 [英] Difference between decorator classes and decorator functions

问题描述

我想这就是它们的称呼方式，但我会举一些例子，以防万一。

I guess that's how they are called, but I will give examples just in case.

装饰类：

class decorator(object):
    def __init__(self, func):
        self.func = func

    def __call__(self, *args, **kwargs):
        print 'something'
        self.func(*args, **kwargs)

装饰函数：

def decorator(func):
    def wrapper(*args, **kwargs):
        print 'something'
        return func(*args, **kwargs)
    return wrapper

使用一个或另一个仅仅是一种口味吗？有什么实际的区别吗？

Is using one or the other just a matter of taste? Is there any practical difference?

推荐答案

如果您可以编写函数来实现装饰器，则应该使用它。但是并非所有装饰器都可以轻松地编写为一个函数-例如，当您要存储某些内部状态时。

If you can write a function to implement your decorator you should prefer it. But not all decorators can easily be written as a function - for example when you want to store some internal state.

class counted(object):
    """ counts how often a function is called """
    def __init__(self, func):
        self.func = func
        self.counter = 0

    def __call__(self, *args, **kwargs):
        self.counter += 1
        return self.func(*args, **kwargs)


@counted
def something():
    pass

something()
print something.counter

我见过人们（包括我自己）经过荒唐的努力，只用函数编写装饰器。我仍然不知道为什么，一个类的开销通常可以忽略不计。

I've seen people (including myself) go through ridiculous efforts to write decorators only with functions. I still have no idea why, the overhead of a class is usually totally negligible.

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