// What is the advantage of Delegates
public static void DelegatesDemo()
{
// A very good example https://buildplease.com/pages/why-delegates/
//1. A delegate is an object which refers to a method or you can say it is a reference type variable that can hold a reference to the methods.
//2. Delegates are mainly used in implementing the call-back methods and events.
//3. Delegates can also be used in “anonymous methods” invocation.
//4. A delegate will call only a method which agrees with its signature and return type.
// A method can be a static method associated with a class or can be an instance method associated with an object, it doesn’t matter.
//5. Multicasting of delegate is an extension of the normal delegate(sometimes termed as Single Cast Delegate).
// It helps the user to point more than one method in a single call.
// Delegates are combined and when you call a delegate then a complete list of methods is called.
// All methods are called in First in First Out(FIFO) order.
// ‘+’ or ‘+=’ Operator is used to add the methods to delegates.
// ‘–’ or ‘-=’ Operator is used to remove the methods from the delegates list.
// multicasting of delegate should have a return type of Void otherwise it will throw a runtime exception.
// Also, the multicasting of delegate will return the value only from the last method added in the multicast. Although, the other methods will be executed successfully.
//Good example
//You're an O/S, and I'm an application.I want to tell you to call one of my methods when you detect something happening.
//To do that, I pass you a delegate to the method of mine which I want you to call.
//I don't call that method of mine myself, because I want you to call it when you detect the something.
//You don't call my method directly because you don't know (at your compile-time) that the method exists (I wasn't even written when you were built);
//instead, you call whichever method is specified by the delegate which you receive at run - time.
LongRunningTask longRunningTask = new LongRunningTask();
longRunningTask.Start(new CallbackDelegate(MyCallbackMthod));
}
private static void MyCallbackMthod(LongRunningTask t, TaskStatus status)
{
Console.WriteLine("The task status is {0}", status);
}
