C＃中某个类的事件如何取消订阅所有处理程序？ [英] How do I unsubscribe all handlers from an event for a particular class in C#?

问题描述

基本的前提：

我有一个房间，当Avatar进入房间内的所有头像时，发布活动。当Avatar离开房间时，我希望它删除该房间的所有订阅。

I have a Room which publishes an event when an Avatar "enters" to all Avatars within the Room. When an Avatar leaves the Room I want it to remove all subscriptions for that room.

在添加头像之前，如何最好取消订阅房间中所有活动的头像到新房间并订阅新房间的活动？

How can I best unsubscribe the Avatar from all events in the room before I add the Avatar to a new Room and subscribe to the new Room's events?

代码如下：

class Room
{
   public event EventHandler<EnterRoomEventArgs> AvatarEntersRoom;
   public event EvnetHandler<LeaveRoomEventArgs> AvatarLeavesRoom;
   public event EventHandler<AnotherOfManyEventArgs> AnotherOfManayAvatarEvents;


   public void AddPlayer(Avatar theAvatar)
   {
      AvatarEntersRoom(this, new EnterRoomEventArgs()); 

      AvatarEntersRoom += new EventHandler<EnterRoomEventArgs>(theAvatar.HandleAvatarEntersRoom);

      AvatarLeavesRoom += new EventHandler<EnterRoomEventArgs>(theAvatar.HandleAvatarEntersRoom);

      AnotherOfManayAvatarEvents += new EventHandler<EnterRoomEventArgs>(theAvatar.HandleAvatarEntersRoom);          

   }

}

class Avatar
{
   public void HandleAvatarEntersRoom(object sender, EnterRoomEventArgs e)
   {
       Log.Write("avatar has entered the room");
   }

   public void HandleAvatarLeaveRoom(object sender, LeaveRoomEventArgs e)
   {
       Log.Write("avatar has left room");
   }

   public void HandleAnotherOfManayAvatarEvents(object sender, AnotherOfManyEventArgs e)
   {
       Log.Write("another avatar event has occurred");
   }
}

推荐答案

委托有一个名为 GetInvocationList（）的方法返回已注册的所有实际代表。因此，假设委托Type（或事件）命名为 MyDelegate ，处理程序实例变量名为 myDlgHandler 你可以写：

Each delegate has a method named GetInvocationList() that returns all the actual delegates that have been registered. So, assuming the delegate Type (or event) is named say MyDelegate, and the handler instance variable is named myDlgHandler, you can write:

Delegate[] clientList = myDlgHandler.GetInvocationList();
foreach (var d in clientList)
       myDlgHandler -= (d as MyDelegate);

涵盖可能为null的情况，

to cover the case where it might be null,

 if(myDlgHandler != null)
  foreach (var d in myDlgHandler.GetInvocationList())
       myDlgHandler -= (d as MyDelegate);

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