如何清除 C# 中的事件订阅? [英] How can I clear event subscriptions in C#?

问题描述

学习以下 C# 类:

c1 {
 event EventHandler someEvent;
}

如果对 c1 的 someEvent 事件有很多订阅，而我想将它们全部清除，那么实现此目的的最佳方法是什么?还要考虑订阅此事件可能是/是 lambdas/匿名委托.

If there are a lot of subscriptions to c1's someEvent event and I want to clear them all, what is the best way to achieve this? Also consider that subscriptions to this event could be/are lambdas/anonymous delegates.

目前我的解决方案是向 c1 添加一个 ResetSubscriptions() 方法，将 someEvent 设置为 null.我不知道这是否有任何看不见的后果.

Currently my solution is to add a ResetSubscriptions() method to c1 that sets someEvent to null. I don't know if this has any unseen consequences.

推荐答案

在类中，您可以将(隐藏的)变量设置为 null.空引用是有效表示空调用列表的规范方式.

From within the class, you can set the (hidden) variable to null. A null reference is the canonical way of representing an empty invocation list, effectively.

在课堂之外，您不能这样做 - 事件基本上公开订阅"和取消订阅"，仅此而已.

From outside the class, you can't do this - events basically expose "subscribe" and "unsubscribe" and that's it.

了解类似场的事件实际上在做什么是值得的——它们同时创建一个变量和一个事件.在类中，您最终会引用变量.您从外部引用该事件.

It's worth being aware of what field-like events are actually doing - they're creating a variable and an event at the same time. Within the class, you end up referencing the variable. From outside, you reference the event.

有关详细信息，请参阅我的关于事件和委托的文章.

See my article on events and delegates for more information.

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