Singleton Factory

source : http://www.bigroom.co.uk/blog/singleton-factory/

== quote ==

package { 

function Singleton( c:Class ):* 
{ 
for( var i:String in instances ) 
{ 
  if( instances[i].constructor === c ) 
  { 
     return instances[i]; 
  } 
} 

var obj:* = new c(); 
instances.push( obj ); 

return obj; 
} 
} 
var instances:Array = new Array();

You can use this function to create an instance of any class (your own or an intrinsic class) as follows (for example):

import flash.geom.Point;
var a:Point = Singleton( Point );

In the comments below, Benny suggested a good improvement to gain a more stable lookup time by using a Dictionary instead of an Array. His suggestion, with minor alterations by me, looks like this.

package {
function Singleton( c:Class ):*
{ return c in instances ? instances[c] : in[c] = new c();
}
}

import flash.utils.Dictionary;
var instances:Dictionary = new Dictionary( false );