类中的Python装饰器

Posted 2021-04-08

我想用类变量制作装饰器。如何使装饰器成为类功能？因为我有很多需要锁定的功能。我不想写下来

with self.lock: or self.lock.release() 

每个功能。这是我的代码！

class Something:
    self.lock = Lock( .. )

    #decorator
    def _lock(self, func):
        def wrapper(*args, **kwargs):
            self.lock.acquire()
            func(*args, **kwargs)
            self.lock.release()
        return wrapper

    @_lock
    def some_func(self,):
        #do something

答案

你必须这样做。它只适用于实例方法，而不适用于函数。

class Something:
    self.lock = Lock( .. )

    #decorator
    def _lock(func):
        def wrapper(self, *args, **kwargs):
            self.lock.acquire()
            r = func(self, *args, **kwargs)
            self.lock.release()
            return r
        return wrapper

    @_lock
    def some_func(self):
        #do something

另一答案

强烈建议如果你想要一种使用装饰器来简化线程锁定的方法，请使用synchronised包中的wrapt装饰器。

有关其设计和合理性的详细信息，请阅读以下内容。帖子中有太多细节要重复这里。

• http://blog.dscpl.com.au/2014/01/the-missing-synchronized-decorator.html
• http://blog.dscpl.com.au/2014/01/the-synchronized-decorator-as-context.html
• http://wrapt.readthedocs.io/en/latest/examples.html

它允许的是：

@synchronized # lock bound to function1
def function1():
    pass

@synchronized # lock bound to function2
def function2():
    pass

@synchronized # lock bound to Class
class Class(object):

    @synchronized # lock bound to instance of Class
    def function_im(self):
        pass

    @synchronized # lock bound to Class
    @classmethod
    def function_cm(cls):
        pass

    @synchronized # lock bound to function_sm
    @staticmethod
    def function_sm():
        pass

要在类的方法中进行更细粒度的锁定，您还可以像上下文管理器一样使用它：

class Class(object):

    @synchronized
    def function_im_1(self):
        pass

    def function_im_2(self):
        with synchronized(self):
            pass

和：

class Class(object):

    @synchronized
    @classmethod
    def function_cm(cls):
        pass

    def function_im(self):
        with synchronized(Class):
            pass

另一答案

阶级函数的含义对我来说不是很清楚。所以我在下面的代码中显示了两个不同的锁，一个用于类方法，另一个用于实例方法。

我们需要在装饰器内调用try...finally时使用func

def synchronized(func):
    """ Assumes that the first parameter of func has `_lock` property
    """
    def wrapper(owner, *args, **kwargs):
        owner._lock.acquire()
        try:
            return func(owner, *args, **kwargs)
        finally:
            owner._lock.release()
    return wrapper


class Something(object):
    _lock = Lock()  # for class methods

    def __init__(self):
        self._lock = Lock()  # for instance methods

    @synchronized
    def instance_method(self):
        print 'instance method invoked...'

    @classmethod
    @synchronized
    def class_method(cls):
        print 'class method invoked...'