我如何子类threading.Event? [英] how do i subclass threading.Event?

问题描述

在Python 2.7.5中:

In Python 2.7.5:

from threading import Event

class State(Event):
    def __init__(self, name):
        super(Event, self).__init__()
        self.name = name

    def __repr__(self):
        return self.name + ' / ' + self.is_set()

我得到:

TypeError:调用元类基础时出错
function()参数1必须是代码，而不是str

TypeError: Error when calling the metaclass bases
function() argument 1 must be code, not str

为什么?

我所了解的关于threading.Event的一切，我从以下中学到的知识: http://docs.python.org/2/library/threading.html?highlight=threading#event-objects

Everything I know about threading.Event I learned from: http://docs.python.org/2/library/threading.html?highlight=threading#event-objects

当它说threading.Event()是类threading.Event的工厂函数时，这是什么意思? (呃……对我来说似乎只是普通的老样子).

What does it mean when it says that threading.Event() is a factory function for the class threading.Event ??? (Uhh... just looks like plain old instanciation to me).

推荐答案

threading.Event不是类，它是threading.py中的函数

threading.Event is not a class, it's function in threading.py

def Event(*args, **kwargs):
    """A factory function that returns a new event.

    Events manage a flag that can be set to true with the set() method and reset
    to false with the clear() method. The wait() method blocks until the flag is
    true.

    """
    return _Event(*args, **kwargs)

此函数返回_Event实例，您可以将_Event子类化(尽管导入和使用带下划线的名称永远不是一个好主意):

Sinse this function returns _Event instance, you can subclass _Event (although it's never a good idea to import and use underscored names):

from threading import _Event

class State(_Event):
    def __init__(self, name):
        super(Event, self).__init__()
        self.name = name

    def __repr__(self):
        return self.name + ' / ' + self.is_set()

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