Question

Anybody know why this is not possible?
If the event is just a MulticastDelegate instance you should be able to reference it in the code. the compiler says EventA can only be on left side of -= or +=.

public delegate void MyDelegate();
public event MyDelegate EventA;

public void addHandlerToEvent(MulticastDelegate md,Delegate d){
 md+=d;

}

///
addHandlerToEvent(EventA,new MyDelegate(delegate(){}));

Answer 1

An event is not a multicast delegate, just like a property is not a field.

C#’s event syntax wraps multicast delegates to make life easier by providing syntactic sugar for adding and removing handler delegates. Your event definition would be compiled to the following:

private MyDelegate _EventA;

public event MyDelegate EventA
{
    [MethodImpl(MethodImplOptions.Synchronized)]
    add 
    { 
        _EventA = (MyDelegate)Delegate.Combine(_EventA, value);
    }

    [MethodImpl(MethodImplOptions.Synchronized)]
    remove 
    { 
        _EventA = (MyDelegate)Delegate.Remove(_EventA, value);
    }
}

The add and remove methods within the expanded event definition are then called when you use operator += and operator -= on the event.

This is done in order to hide the internals of the multicast delegate, but expose a simple way to implement publishing/subscribing to events. Being able to get the underlying delegate (outside of the class where it’s defined) would break that intentional encapsulation.