Singleton Factory Class C#

 

 

class Base {         public virtual string Message         {             get             {                 return "Message From Base";             }         } } class Detived1 : Base {         public override string Message         {             get             {                 return "Message From Detived1";             }         } } class Detived2 : Base {         public override string Message         {             get             {                 return "Message From Detived2";             }         } } class ObjectFactory {      public Base this[string className]      {          get          {             switch (className.ToUpper())             {                case "DERIVED1":                     return new Detived1();                case "DERIVED2":                     return new Detived2();                 default:                     return new Base();              }           }      }      public static ObjectFactory Instance      {          get          {               return _Instance;          }      }      private ObjectFactory() { }      private static readonly ObjectFactory _Instance = new ObjectFactory(); } class App {    public static void Main()    {             Console.WriteLine(ObjectFactory.Instance["DERIVED1"].Message);             Console.WriteLine(ObjectFactory.Instance["DERIVED1"].Message);             Console.WriteLine(ObjectFactory.Instance["Test"].Message);    } }