How can I use addEventListener and return something that's changed from it in Actionscript?

private function getTitle(src:String):String{
            var urlLoader:URLLoader = new URLLoader();
            var rssURLRequest:URLRequest = new URLRequest(src);
            var rss:XML = new XML;
            var t:String = src;
            urlLoader.addEventListener(Event.COMPLETE, 
                                       function(event:Event):void{
                                           rss = XML(urlLoader.data);
                         开发者_StackOverflow                  t = rss.channel.title.toString();
                                        });
            return t;
        }

I'm aware that this code doesn't work because the anonymous function doesn't work until after t is returned. How would I make it so that it works?

You won't be able to return the loaded data from this method. The reason for this is because the loading is asynchronous and doesn't not block the execution of subsequent code. Your best option is to move the vars out of the scope of the function and to write a second function to handle the COMPLETE event.

Something like the following should work:

var rss:XML;
var t:String;
var path:String = "some path";
var urlLoader:URLLoader = new URLLoader();


private function getTitle(src:String):String
{
     urlLoader.load( new URLRequest( src ) );
     urlLoader.addEventListener(Event.COMPLETE, onComplete );
}

private function onComplete(event:Event):void
{
     rss = XML(urlLoader.data);
     t = path + rss.channel.title.toString();
}

I realize that this doesn't really answer the question directly, though it is the best practice for handling data loading. If you really want to stop any code from executing before the data is loaded, it may be possible use a while loop after the addEventListener line to halt the player from until the data is loaded. This should probably be considered a not so elegant hack though.

private function getTitle(src:String):String
{
     var urlLoader:URLLoader = new URLLoader();
     var rssURLRequest:URLRequest = new URLRequest(src);
     var rss:XML = new XML;
     var t:String = src;
     var complete:Boolean;
     urlLoader.addEventListener(Event.COMPLETE, 
                                  function(event:Event):void
                                  {
                                       rss = XML(urlLoader.data);
                                       t = rss.channel.title.toString();
                                       complete = true;
                                  });
     while( !complete ) { /* sleep hack */  }
     return t;
}

I haven't tested this, but it seems like it could work. The first example is recommended.