package {
    import flash.display.DisplayObject;
    import flash.display.Sprite;
    import flash.errors.IllegalOperationError;
    import flash.events.Event;

    public class ApplicationDomainExample extends Sprite {
        private var loader:ClassLoader;
        
        public function ApplicationDomainExample() {
            loader = new ClassLoader();
            loader.addEventListener(ClassLoader.LOAD_ERROR, loadErrorHandler);
            loader.addEventListener(ClassLoader.CLASS_LOADED, classLoadedHandler);
            loader.load("RuntimeClasses.swf");
        }
        
        private function loadErrorHandler(e:Event):void {
            throw new IllegalOperationError(e);
        }
        
        private function classLoadedHandler(e:Event):void {
            var greeterClassRef:Class = loader.getClass("Greeter");
            var greeter:Object = new greeterClassRef();
            trace(greeter.greet()); // Hello World
            
            greeterClassRef = loader.getClass("VisualGreeter");
            greeter = new greeterClassRef();
            addChild(DisplayObject(greeter));
            greeter.greet();
        }
    }
}

import flash.display.Loader;
import flash.errors.IllegalOperationError;
import flash.events.Event;
import flash.events.EventDispatcher;
import flash.events.IOErrorEvent;
import flash.events.SecurityErrorEvent;
import flash.net.URLRequest;
import flash.system.ApplicationDomain;
import flash.system.LoaderContext;

class ClassLoader extends EventDispatcher {
    public static var CLASS_LOADED:String = "classLoaded";
    public static var LOAD_ERROR:String = "loadError";
    private var loader:Loader;
    private var swfLib:String;
    private var request:URLRequest;
    private var loadedClass:Class;
    
    public function ClassLoader() {
        loader = new Loader();
        loader.contentLoaderInfo.addEventListener(Event.COMPLETE, completeHandler);
        loader.contentLoaderInfo.addEventListener(IOErrorEvent.IO_ERROR, ioErrorHandler);
        loader.contentLoaderInfo.addEventListener(SecurityErrorEvent.SECURITY_ERROR, securityErrorHandler);
    }
    
    public function load(lib:String):void {
        swfLib = lib;
        request = new URLRequest(swfLib);
        var context:LoaderContext = new LoaderContext();
        context.applicationDomain = ApplicationDomain.currentDomain;
        loader.load(request, context);
    }
        
    public function getClass(className:String):Class {
        try {
            return loader.contentLoaderInfo.applicationDomain.getDefinition(className);
        }
        catch(e:Error) {
            throw new IllegalOperationError(className + " definition not found in " + swfLib);
        }
        return null;    
    }
    
    private function completeHandler(e:Event):void {
        dispatchEvent(new Event(ClassLoader.CLASS_LOADED));
    }
    
    private function ioErrorHandler(e:Event):void {
        dispatchEvent(new Event(ClassLoader.LOAD_ERROR));
    }
    
    private function securityErrorHandler(e:Event):void {
        dispatchEvent(new Event(ClassLoader.LOAD_ERROR));
    }
}