Question

Is it possible to detect if event has any listeners? (I need to dispose my event provider object, if nobody needs it)

Answer 1

Assume the class is in a 3rd party library and it can’t be modified:

    public class Data
    {
       public event EventHandler OnSave;
       //other members
    }

In your program:

    Data d = new Data();
    d.OnSave += delegate { Console.WriteLine("event"); };
    var handler = typeof(Data).GetField("OnSave", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(d) as Delegate;

    if (handler == null)
    {
        //no subscribers
    }
    else
    {
        var subscribers = handler.GetInvocationList();
        //now you have the subscribers
    }