Flash / Flex / ActionScript/Class/Singleton

Singleton Pattern

   <source lang="java">

package {

 public class Singleton {
 
   static var instanceCount:uint = 0;
   public function Singleton() {
     instanceCount++;
     if(instanceCount == 1) {
       trace("First Singleton class instance");
     } else {
       trace("Singleton class allows only one instance");
     }
   }
 }
    

}

       </source>
   
  

Singleton pattern with getInstance

   <source lang="java">

package {

 public class Singleton {
   private static var instance:Singleton;
   private static var allowInstance:Boolean;
   public function Singleton() {
     if(!allowInstance) { 
       throw new Error("Error: use Singleton.getInstance() instead of new keyword");
     }
   }
   public static function getInstance():Singleton {
      if(instance == null) {
        allowInstance = true;
        instance = new Singleton();
        trace("Singleton instance created");
        allowInstance = false;
      } else { 
        trace("Singleton instance already exists");
      }
      return instance;
   }
   public function doSomething():void {
     trace("doing something");
   }
 }

}

       </source>