ActionScript Singleton

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The singleton pattern is a design pattern that is used to restrict instantiation of a class to one object. Often a singleton is used as the Model in a Model View Controller (MVC) structure. Useful if you're looking for a quick (and better) way to store global variables and data than dumping them in a global or root holder.

A Singleton class (Model.as)

package
{
	public class Model
	{
		private static var instance:Model;
 
		// vars
		public var myVar:String;
 
		//////////////////////////////////////////////////////////////////////
		//
		// instance
		//
		//////////////////////////////////////////////////////////////////////
 
		public static function getInstance():Model
		{
			if ( instance == null ) instance = new Model();
			return instance as Model;
		}
	}
}

How to use

import Model;
 
private var model:Model = Model.getInstance();
 
model.myVar = "something";

You can also make the entire Model bindable in Flex... 

package
{
	[Bindable]
	public class Model...

Usage...

<mx:Script>
<![CDATA[
 
import Model;
 
[Bindable]
private var model:Model = Model.getInstance();
 
model.myVar = "something";
 
]]>
</mx:Script>