AS3 Singleton class with parameterised constructor
Posted by ravi | Posted in Customization, flex | Posted on 23-02-2010
Tags: Patterns, singleton
0
As many of you already know, in AS3 there is no direct way to create singleton class i.e there is no keyword Singleton or any other equivalent keyword using which this can be accomplished. But there is a simple work around to create singleton class. The code below shows this:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | public class Services extends EventDispatcher { public static function getInstance(url:String) : Services { if ( servicesLocator == null ) { servicesLocator = new Services(url); } return servicesLocator; } public function Services(url:String) { if ( servicesLocator != null ) { throw new Error( "Only one Services instance should be instantiated" ); } ENDPOINT_URL=url gateway=new HTTPService(); gateway.resultFormat="e4x"; gateway.url = ENDPOINT_URL; gateway.method = "POST"; gateway.useProxy = false; gateway.addEventListener(ResultEvent.RESULT, resultHandler); gateway.addEventListener(FaultEvent.FAULT, faultHandler); } } |
the way to create object now is like this:
1 | public var servicesInstance:Services =Services.getInstance("serviceURL.php"); |
we’re defining here a static function called getInstance which calls the constructor only if servicesLocator object is null or not initialized already. A sinlgeton class is particularly of high use for HTTPService object as it allows single point of handling all the requests in this way.