How does the + operator work for combining delegates?

Question

For example:

delegate void SomeDelegate();

SomeDelegate a = new SomeDelegate( () => Console.WriteLine(\"A\") );
SomeDelegate b = new SomeDelegate( () =&g         


        

Answer 1

It is done using Delegate.Combine static method.

SomeDelegate c = Delegate.Combine(a, b) as SomeDelegate;

When using += operator it is just the same actually.

// This is the same...
eventSource.onEvent += OnEvent;

// ...as this.
eventSource.onEvent = Delegate.Combine(
    eventSource.onEvent,
    Delegate.CreateDelegate(typeof(EventSource.OnEvent), this, "OnEvent")
    ) as EventSource.OnEvent;

MulticastDelegate class (the class behind delegate keyword) do have a list of invocations, but this list is immutable. Each time you combine delegates with the += operator, a new MulticastDelegate instance get created combining the invocation list of the former two Delegate objects.