C# How to unsubscribe all event handlers from a given event?

Question

Is there a simple way to iterate all over the handlers subscribed to a given event? My problem is that clients subscribe but forget to unsubscribe so a memory leak happens. I need a way for an object to disconnect all the handlers of its events in the Dispose method so a leak would not happen - at least not because of events.

Answer 1

Set null to your event: MyEvent = null;

But it is really better to make clients unsubscribing from your event.

Answer 2

An alternative approach is to use so-called "weak delegate" pattern. When you use this technique, the event references clients only using WeakReference which doesn't keep them in memory. The clients will be garbage collected when they are no longer referenced from other part of the application (and the handler can be also unregistered automatically when the client is collected).

This is usually used to solve the problem with clients "forgetting" to unsubscribe from a .NET event, so it sounds like this might be well suited for your problem.

• Dusing Campbell has a nice article about weak delegates.
• I also liked this overview at CodeProject, which discusses most of the scenarios.
• Weak Events are also used in WPF, but this approach seems a bit complicated (to me).