Store a list of EventHandlers to unsubscribe from

问题:

I have a class with a method, Register that subscribes to a number of events on classes that it contains, using the standard aClass.SomeEvent += the_handler. This class also has an Unregister method that unsubscribes from these events using -=. This works just fine but we're finding that if we add a new event to subscribe to that it's very easy to forget to include the unsubscription in Unregister. This manual method of maintaining event subscriptions is proving to be fragile.

Is there a way to maintain a list of subscriptions that can be iterated over and unsubscribed from dynamically? (And potentially iterate over and re-subscribe when calling Register after Unregister).

Some details: The class has a reference to 3 other classes (currently, but not definitively limited to 3), the various events on these classes are all of type EventHandler or EventHandler<T>.

回答1:

how about getting invocation list from the EventHandler.GetInvocationList() and then ierate through and manually remove/unregister them ? note, you only have access to the GetInvationList() method from the class that has that EventHandler, so you might need to expose a method UnregisterAll() to make sure it removes all the delagates in the event invocation list

you can also make sure your class inherits IDisposable and with using(){ } it will call Dispose which will clean up all subscribers

回答2:

After a thorough look through SO I found this answer:

C# Dynamic Event Subscription

That does what I want (almost). I don't like having to name events using strings as and such I won't be pursuing this design any further. Even though it's not the design I want, the answer shows a very useful method to achieve the desired behaviour and as such I'm marking this as accepted.