C# in Depth

Delegates37A COMPLETE EXAMPLE AND SOME MOTIVATIONIt’s easiest to see all this in action in a complete example—finally, something we canactually run! As there are lots of bits and pieces going on, I’ve included the wholesource code this time rather than using snippets. There’s nothing mind-blowing in listing2.1, so don’t expect to be amazed—it’s just useful to have concrete code to discuss.Listing 2.1Using delegates in a variety of simple waysusing System;delegate void StringProcessor(string input);BDeclaresdelegate typeclass Person{}string name;public Person(string name){this.name = name;}public void Say(string message){Console.WriteLine ("{0} says: {1}", name, message);}CDeclares compatibleinstance methodclass Background{public static void Note(string note){Console.WriteLine ("({0})", note);}DDeclares compatiblestatic method}class SimpleDelegateUse{static void Main(){Person jon = new Person("Jon");Person tom = new Person("Tom");StringProcessor jonsVoice, tomsVoice, background;jonsVoice = new StringProcessor(jon.Say);tomsVoice = new StringProcessor(tom.Say);background = new StringProcessor(Background.Note);E Createsthreedelegateinstances}}jonsVoice("Hello, son.");tomsVoice.Invoke("Hello, Daddy!");background("An airplane flies past.");Invokes delegateinstancesTo start with, we declare the delegate type B. Next, we create two methods (Cand D) that are both compatible with the delegate type. We’ve got one instancemethod (Person.Say) and one static method (Background.Note) so that we can seeFLicensed to Rhona Hadida