The Singleton Pattern

• Just one please.
• We have seen one example of this with the logger a while ago.
  • This is a class using only static methods and data.
  • In some sense, this is not really a class.
  • It has no instanciation.
• This is a more improved version.
• Singletons do have some problems
  • Proper initialization of multiple singletons, especially if they rely on each other is problematic.
  • They might also have problems at program shutdown.
  • They complicate debugging.
• But

  • class Singleton {
        public:
           virtual Singleton & Instance(){
              static Singleton instance;
              return instance;
           }
           // other public methods.
        private:
           Singleton();
    }