c# - Passing delegates as parameters for mediator/subscriber pattern -

i'm looking appropriate , elegant way create mediator/subscriber architecture typed callbacks.

let's suppose have class 'events' i.e. delegates:

public class e {     public delegate void somethinghappened (float a, int b);     public delegate void progressfinished (int[] c); } 

now want create mediator class register callbacks delegates , dispatch callbacks supplied parameters:

public class mediator {     public static void register ( ???, action callback)     {         // supplied delegate += callback     }      public static void dispatch ( ???, params object[] list)     {         // executing supplied delegate params: delegate(list)     } } 

so use following way:

// class a: mediator.register (e.somethinghappened, onsomethinghappened); private void onsomethinghappened (float a, int b) {     //.......... }  // class b: mediator.dispatch (e.somethinghappened, 0.1f, 'qwe'); 

now problem can't pass delegate parameter register or dispatch. how solve problem?

you should take different approach: let senders dispatch messages, , have mediator dispatch them different handlers based on type.

using generics, refactored to:

// handlers should differentiated message type public class somethinghappenedmessage {     public float { get; set; }     public int b { get; set; } }  public class mediator {     private readonly dictionary<type, object> _dict = new dictionary<type, object>();      public void register<tmessage>(action<tmessage> callback)     {         _dict[typeof(tmessage)] = callback;     }      public void dispatch<tmessage>(tmessage msg)     {         var handler = _dict[typeof(tmessage)] action<tmessage>;         handler(msg);     } } 

or, might have multiple handlers each message type:

public class mediator {     readonly dictionary<type, list<object>> _handlersbytype = new dictionary<type, list<object>>();      public void register<tmessage>(action<tmessage> callback)     {         list<object> handlers;         if (!_handlersbytype.trygetvalue(typeof(tmessage), out handlers))             _handlersbytype[typeof(tmessage)] = handlers = new list<object>();          handlers.add(callback);     }      public void dispatch<tmessage>(tmessage msg)     {         list<object> handlers;         if (!_handlersbytype.trygetvalue(typeof(tmessage), out handlers))             return;          foreach (action<tmessage> handler in handlers)             handler(msg);     } }