title: Actionscript 3: Force program to wait until event handler is called
body: <p>I have an AS 3.0 class that loads a JSON file in using a URLRequest.</p>
  
  <pre><code>package {
  
      import flash.display.MovieClip;
      import flash.display.Loader;
      import flash.net.URLRequest;
      import flash.net.URLLoader;
      import flash.events.Event;
  
      public class Tiles extends MovieClip {
  
          private var mapWidth:int,mapHeight:int;
          private var mapFile:String;
  
          private var mapLoaded:Boolean=false;
  
          public function Tiles(m:String) {
  
              init(m);
  
          }
  
          private function init(m:String):void {
  
              // Initiates the map arrays for later use.
              mapFile=m;
  
              // Load the map file in.
              var loader:URLLoader = new URLLoader();
              loader.addEventListener(Event.COMPLETE, mapHandler);
              loader.load(new URLRequest("maps/" + mapFile));
  
  
          }
  
          private function mapHandler(e:Event):void {
  
              mapLoaded=true;
              mapWidth=3000;
  
          }
  
          public function getMapWidth():int {
  
              if (mapLoaded) {
  
                  return (mapWidth);
  
              } else {
  
                  return(-1);
              }
  
          }
  
      }
  
  }
  </code></pre>
  
  <p>When the file is finished loading, the mapHandler event makes changes to the class properties, which in turn are accessed using the getMapWidth function. However, if the getMapwidth function gets called before it finishes loading, the program will fail.</p>
  
  <p>How can I make the class wait to accept function calls until after the file is loaded?</p>