Delegates similar to NotifyEvents or procedures of object in Delphi,
We can register or unregister handlers in calling code
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using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace Delegates { class Program { static void Main(string[] args) { SomeClass sc = new SomeClass(); sc.RegisterHandler(new SomeClass.SomeDelegate(DelegateHandler)); sc.RegisterHandler(new SomeClass.SomeDelegate(DelegateHandler2)); sc.UnRegisterHandler(new SomeClass.SomeDelegate(DelegateHandler2)); sc.SomeMethod(); // will fire list of handlers Console.ReadLine(); } public static void DelegateHandler(string Amessage) { Console.WriteLine("Delegate handler message="+Amessage); } public static void DelegateHandler2(string Amessage) { Console.WriteLine("Another handler message = "+Amessage); } } class SomeClass { // delegate block public delegate void SomeDelegate(string Amessage); private SomeDelegate listOfHandlers; public void RegisterHandler(SomeDelegate method) {listOfHandlers += method;} public void UnRegisterHandler(SomeDelegate method) { listOfHandlers -= method; } //do something in class public void SomeMethod() { //some code if (listOfHandlers != null) { listOfHandlers("hello from delegate method"); } //some code } } } |