Question

我写了一些课：

public class A 
{
    public A()
    {
        serviceAdapter.CompletedCallBackEvent += new EventHandler( foo );
        .
        .
        .
    }

    void foo(object sender, EventArgs e)
    {
        serviceAdapter.CompletedCallBackEvent -= new EventHandler( foo );
    }
}

现在，我想用匿名方法更改此回调侦听器 - 但我不知道如何在匿名方法中删除回调侦听器。

class A
{
    public A()
    {
            serviceAdapter.CompletedCallBackEvent += delegate( object sender, EventArgs ee )
            {
                  ... need to remove the listener to the event. 
            }
    }
}

Answer 1

您可以简单地将您的委托/处理程序分配给私有变量。

private EventHander _handler = null;

public A()
{        
    _handler = delegate( object sender, EventArgs ee)
        {          
            ServiceAdapter.CompletedCallBackEvent -= _handler;
        };
    ServiceAdapter.CompletedCallBackEvent += _handler;
}

Answer 2

您无法删除此类匿名委托。请参阅有关匿名代表的MSDN文章。另外值得一读this article

您可以这样做：

     public A()
     {
         EventHandler myHandler = null;
         myHandler = new EventHandler(delegate(object s, EventArgs e)
             {
                 serviceAdapter.CompletedCallbackEvent -= myHandler;
             });

         serviceAdapter.CompletedCallBackEvent += myHandler;
     }

如何删除匿名方法上的回调监听？

2 个答案: