This is a sample of event implementation on C#. output: 1HeLLo, WorLd! : on B 1 Hello, World! : on E(1) 1H ello, World! : on E(2) -11 : on D 11 : on E(1) 11 : on E(1) 22 : on E(2) 22 : on E(2)

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Project1 {
	class Program {
		static void Main(string[] args) {
			EventManager em = new EventManager();
			A a = new A(em);
			B b = new B(em);
			C c = new C(em);
			D d = new D(em);
			E e1 = new E(em, 1);
			E e2 = new E(em, 2);
			a.foo("Hello, World!");
			c.foo(10);
		}
	}
	interface Event {}
	class AEvent : Event {
		public string Value{get; set;}
		public AEvent(string s) {
			Value = s;
		}
	}
	class CEvent : Event {
		public int Value{get; set;}
		public CEvent(int i) {
			Value = i;
		}
	}
	class EventManager {
		private Dictionary<Type, List<Action<Event>>> listeners = new Dictionary<Type, List<Action<Event>>>();
		public void addListener<T>(Action<T> a) where T : Event {
			if(!listeners.ContainsKey(typeof(T)))
				listeners[typeof(T)] = new List<Action<Event>>();
			listeners[typeof(T)].Add(e => a((T)e));
		}
		public void HappenEvent(Event e) {
			List<Action<Event>> actions = listeners[e.GetType()];
			if(actions != null)
				actions.ForEach(action => action(e));
		}
	}
	class A {
		private EventManager em;
		public A(EventManager em) {
			this.em = em;
		}
		public void foo(string s) {
			em.HappenEvent(new AEvent(1 + s));
		}
	}
	class B {
		private EventManager em;
		public B(EventManager em) {
			this.em = em;
			em.addListener<AEvent>(e => Console.WriteLine(e.Value.Replace("l", "L") + " : on B"));
		}
	}
	class C {
		private EventManager em;
		public C(EventManager em) {
			this.em = em;
		}
		public void foo(int i) {
			em.HappenEvent(new CEvent(1 + i));
		}
	}
	class D {
		private EventManager em;
		public D(EventManager em) {
			this.em = em;
			em.addListener<CEvent>(e => Console.WriteLine((-e.Value) + " : on D"));
		}
	}
	class E {
		private EventManager em;
		public E(EventManager em, int i) {
			this.em = em;
			em.addListener<CEvent>(e => Console.WriteLine(e.Value * i + " : on E(" + i + ")"));
			em.addListener<AEvent>(e => Console.WriteLine(e.Value.Insert(i, " ") + " : on E(" + i + ")"));
			em.addListener<CEvent>(e => Console.WriteLine(e.Value * i + " : on E(" + i + ")"));
		}
	}
}