How do static events compare to non-static events in C#?

Question

I just realized static events exist - and I'm curious how people use them. I wonder how the relative comparison holds up to static vs. instance methods. For instance, a static method is basically a global function. But I've always associated events with instances of objects and I'm having trouble thinking of them at the global level.

Here some code to refer to if it helps an explanation:

void Main()
{
    var c1 = new C1();
    c1.E1 += () => Console.WriteLine ("E1");
    C1.E2 += () => Console.WriteLine ("E2");
    c1.F1();
}

// <<delegate>>+D()
public delegate void D();

// +<<event>>E1
// +<<class>><<event>>E2
// +F()
//      <<does>>
//          <<fire>>E1
//          <<fire>>E2
public class C1
{
    public void F1()
    {
        OnE1();
        OnE2();
    }
    public event D E1;
    private void OnE1()
    {
        if(E1 != null)
        {
            E1();
        }
    }
    static public event D E2;
    static private void OnE2()
    {
        if(E2 != null)
        {
            E2();
        }
    }
}

Answer 1

Be wary of static events. Remember that, when an object subscribes to an event, a reference to that object is held by the publisher of the event. That means that you have to be very careful about explicitly unsubscribing from static events as they will keep the subscriber alive forever, i.e., you may end up with the managed equivalent of a memory leak.