Esempio di singleton [Actionscript]

class Singleton
{
    private static var istanza:Singleton = null;
    private function Singleton ( )
    {
    }
    public static function getInstance( ):Singleton
    {
        if (Singleton.istanza == null)
        {
            Singleton.istanza = new Singleton( );
        }
        return Singleton.istanza;
    }
    public function helloWorld ( ):Void
    {
        trace("Hello World!");
    }
}
class usaSingleton
{
    public function helloWorld(): Void
    {
        Singleton.getInstance().helloWorld();
    }
}