如何注销“匿名”事件处理程序[重复]

为匿名委托的实例指定一个名称:

EventHandler<NewEventArg> handler = delegate(object sender, NewEventArgs e)
{
    //some code
};

Subject.NewEvent += handler;
Subject.NewEvent -= handler;

如果需要注销事件,我建议避免事件处理程序的匿名委托。

在这种情况下,将其分配给本地方法会更好—您可以完全取消订阅事件。

要在第一次调用时删除处理程序,请执行以下操作:

//SubjectType Subject = ..... already defined if using (2)

EventHandler handler = null;
handler = delegate(object sender, EventArgs e)
{
    // (1)
    (sender as SubjectType).NewEvent -= handler;
    // or
    // (2) Subject.NewEvent -= handler;

    // do stuff here
};

Subject.NewEvent += handler;

    class Program {
    static void Main(string[] args) {
        A someClass = new A();
        someClass.SomeEvent += delegate(object sender, EventArgs e) {
            throw new NotImplementedException();
        };

        someClass.ClearEventHandlers();
        someClass.FireEvent();

        Console.WriteLine("No error.");
    }

    public class A {
        public event EventHandler SomeEvent;

        public void ClearEventHandlers() {
            Delegate[] delegates = SomeEvent.GetInvocationList();
            foreach (Delegate delegate in delegates) {
                SomeEvent -= (EventHandler) delegate;
            }
        }

        public void FireEvent() {
            if (SomeEvent != null) {
                SomeEvent(null, null);
            }
        }
    }
}

    var handler = new EventHandler(delegate(object o, EventArgs e)
    {
        //do something...
    };

    Subject.NewEvent += handler;

    // later on while handler is still in scope...

    Subject.NewEvent -= handler;

您是否需要出于泄漏以外的原因取消注册?

关于“或只允许内存泄漏”位,当垃圾收集器清理主题时,您的匿名委托也应该清理,因此不应该有泄漏。

还有另一个问题(我的问题)涉及到一些(太多)细节: Weak event handler model for use with lambdas .

但是现在, Reactive Framework