static public class Messenger<T, U> 
{
    private static Dictionary<string, Delegate> eventTable = MessengerInternal.eventTable;

    static public void AddListener(string eventType, Callback<T, U> handler) 
    {
        MessengerInternal.OnListenerAdding(eventType, handler);
        eventTable[eventType] = (Callback<T, U>)eventTable[eventType] + handler;
    }

    static public void RemoveListener(string eventType, Callback<T, U> handler) 
    {
        MessengerInternal.OnListenerRemoving(eventType, handler);
        eventTable[eventType] = (Callback<T, U>)eventTable[eventType] - handler;
        MessengerInternal.OnListenerRemoved(eventType);
    }

    static public void Broadcast(string eventType, T arg1, U arg2) 
    {
        Broadcast(eventType, arg1, arg2, MessengerInternal.DEFAULT_MODE);
    }

    static public void Broadcast(string eventType, T arg1, U arg2, MessengerMode mode) 
    {
        MessengerInternal.OnBroadcasting(eventType, mode);
        Delegate d;
        if (eventTable.TryGetValue(eventType, out d)) {
            Callback<T, U> callback = d as Callback<T, U>;
            if (callback != null) {
                callback(arg1, arg2);
            } else {
                throw MessengerInternal.CreateBroadcastSignatureException(eventType);
            }
        }
    }
}