Csharp/C Sharp/Design Patterns/Singleton Pattern

Singleton Pattern Demo

<source lang="csharp">

using System; sealed class MyClass {

   private static bool instanceFlag = false;
   public static MyClass GetMyClass() {
       if (!instanceFlag) {
           instanceFlag = true;
           return new MyClass();
       } else {
           throw new Exception("An engine has already been created!");
       }
   }
   private MyClass() {
       Console.WriteLine("An MyClass");
   }

}

class Client {

   static void Main(string[] args) {
       Console.WriteLine("Attempting to get first engine");
       try {
           MyClass eng = MyClass.GetMyClass();
       } catch (Exception e) {
           Console.WriteLine(e.Message);
       }
       Console.WriteLine("Attempting to get second engine");
       try {
           MyClass eng = MyClass.GetMyClass();
       } catch (Exception e) {
           Console.WriteLine(e.Message);
       }
   }

}

</source>