Overriding Interfaces

   

/*
Learning C# 
by Jesse Liberty

Publisher: O'Reilly 
ISBN: 0596003765
*/
 using System;

 namespace OverridingInterfaces
 {
     interface IStorable
     {
         void Read();
         void Write();
     }

     // Simplify Document to implement only IStorable
     class Document : IStorable
     {
         // the document constructor
         public Document(string s)
         {
             Console.WriteLine(
                 "Creating document with: {0}", s);
         }

         // Make read virtual
         public virtual void Read()
         {
             Console.WriteLine(
                 "Document Read Method for IStorable");
         }

         // NB: Not virtual!
         public void Write()
         {
             Console.WriteLine(
                 "Document Write Method for IStorable");
         }
     }

     // Derive from Document
     class Note : Document
     {
         public Note(string s):
             base(s)
         {
             Console.WriteLine(
                 "Creating note with: {0}", s);
         }

         // override the Read method
         public override void Read()
         {
             Console.WriteLine(
                 "Overriding the Read method for Note!");
         }

         // implement my own Write method
         public new void Write()
         {
             Console.WriteLine(
                 "Implementing the Write method for Note!");
         }
     }

     public class OverridingInterfacesTester
     {
         public void Run()
         {
             // Create a Document object
             Document theNote = new Note("Test Note");

             // direct call to the methods
             theNote.Read();
             theNote.Write();

             Console.WriteLine("
");

             // cast the Document to IStorable
             IStorable isNote = theNote as IStorable;
             if (isNote != null)
             {
                 isNote.Read();
                 isNote.Write();
             }
             Console.WriteLine("
");

             // create a note object
             Note note2 = new Note("Second Test");

             // directly call the methods
             note2.Read();
             note2.Write();
             Console.WriteLine("
");

             // Cast the note to IStorable
             IStorable isNote2 = note2 as IStorable;
             if (isNote != null)
             {
                 isNote2.Read();
                 isNote2.Write();
             }


         }

         static void Main()
         {
             OverridingInterfacesTester t = new OverridingInterfacesTester();
             t.Run();
         }
     }
 }