How to pass an event to a method?

by

My original answer was suitable from within the class that defined the event, but you’ve since updated your question to reflect that you wish to accomplish this from outside the defining class, so I’ve stricken that.

Only the class that defines an event can refer to the implicit delegate variable that the event uses. From outside that class, you only have access to the add and remove methods, via += and -=. This means that you can’t do what you’re asking, directly. You can, however, use a functional approach.

class A{
    public event EventHandler Event1;

    public void TriggerEvent1(){
        if(Event1 != null)
            Event1(this, EventArgs.Empty);
    }
}

class B{
    static void HandleEvent(object o, EventArgs e){
        Console.WriteLine("Woo-hoo!");
    }

    static void AttachToEvent(Action<EventHandler> attach){
        attach(HandleEvent);
    }

    static void Main(){
        A a = new A();
        AttachToEvent(handler=>a.Event1 += handler);
        a.TriggerEvent1();
    }
}

More Related Contents:

  1. How to remove a lambda event handler [duplicate]
  2. What are the differences between delegates and events?
  3. C#: Difference between ‘ += anEvent’ and ‘ += new EventHandler(anEvent)’
  4. Difference between events and delegates and its respective applications [closed]
  5. Is it bad to not unregister event handlers?
  6. Is there a downside to adding an anonymous empty delegate on event declaration?
  7. How do I Unregister ‘anonymous’ event handler [duplicate]
  8. Difference between wiring events with and without “new”
  9. Super-simple example of C# observer/observable with delegates
  10. How do C# Events work behind the scenes?
  11. Assigning events in object initializer
  12. C# pattern to prevent an event handler hooked twice [duplicate]
  13. How to ensure an event is only subscribed to once
  14. How to handle add to list event?
  15. C# Generics won’t allow Delegate Type Constraints
  16. Difference between the KeyDown Event, KeyPress Event and KeyUp Event in Visual Studio
  17. How would it be possible to remove all event handlers of the ‘Click’ event of a ‘Button’?
  18. Are C# events synchronous?
  19. How to correctly unregister an event handler
  20. How can I clear event subscriptions in C#?
  21. Removing event handlers
  22. C#: Triggering an Event when an object is added to a Queue
  23. Should I always disconnect event handlers in the Dispose method?
  24. Events – naming convention and style
  25. How to subscribe to other class’ events in C#?
  26. Passing Data Between 3 Separate WinForms [duplicate]
  27. Return a value from an Event — is there a Good Practice for this?
  28. Detect when a form has been closed c#
  29. Is it good idea to use “Control.CheckForIllegalCrossThreadCalls = false” [duplicate]
  30. C# Dynamic Event Subscription

Leave a Comment