AS3 reference custom property in a custom class for a library symbol - actionscript-3

Question

So I've done a fair amount of searching through SO and couldn't quite find the answer to this question. I have a movieclip in my symbol library that's exported for actionscript, and I've written a custom class for it. It mostly works great except for when I try to access a custom private property after I've added the movieclip to the stage. Below's an example:
package {
public class MyMovieClip extends MovieClip {
private var _isEnabled:Boolean = false;
public function MyMovieClip():void {
trace(this);
}
public function set isEnabled( b:Boolean ):void {
_isEnabled = b;
}
public function get isEnabled():Boolean {
return _isEnabled;
}
}
}
And then I have another class where I am adding instances of the movieclip to the stage in a loop:
package {
public class MyOtherClass extends MovieClip {
public var myMC:MyMovieClip;
public var docClass:*;
public function MyOtherClass( docRef:* ):void { // passing in a reference to the DocumentClass so I can access the stage
docClass = docRef;
init();
}
public function init():void {
for(var i:int=0; i<6; i++) {
var myMC:MyMovieClip = new MyMovieClip; // instantiate the movieclip which is exported for actionscript and has a custom class
//set a few native properties
myMC.name = "myMC" + i; //setting the name so I can reference this movieclip after it's been added to stage
myMC.y = myMC.height * i + 20;
myMC.x = 20;
myMC.alpha = .7;
}
dispatchEvent(new Event(MyOtherClass.MOVIECLIPS_ADDED)); // just to be safe, let's dispatch a custom event when all movieclips have been added
}
public function traceEnabled():void {
trace(docClass.stage.getChildByName("myMC1").isEnabled); // this throws: 1119: Access of possibly undefined property isEnabled through a reference with static type flash.display:DisplayObject
}
}
}
And finally I instantiate MyOtherClass inside my document class:
package {
public class DocumentClass extends MovieClip {
public var myOtherClass:MyOtherClass;
public function DocumentClass():void {
addEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
}
public function onAddedToStage(e:Event):void {
myOtherClass = new MyOtherClass(); // upon instantiation, init is called in MyOtherClass and all of my movieclips are added to the sage
}
}
}
What gives? Why can't I access the MyMovieClip property, isEnabled, after it's been added to the stage? Is there another way? (Thanks in advance for any help)

Answer 1

Internally all children of a DisplayObjectContainer are referenced as DisplayObject, so when you use getChildByName, it returns a DisplayObject.
In order to access your custom properties without causing a compile-time error, you would need to cast the result of getChildByName as the Class of your custom properties. See the code below.
That however isn't your only issue (though it's the reason for the error, once you correct you will get runtime errors as well).
In your creation loop, your not adding myMC to the display list, so calling stage.getChildByName() will return null because your clips aren't on the stage.
Your also not adding your myOtherClass to the display list in the posted code.
Also, storing a reference to the document class isn't really needed. Just add the addedToStage listener in MyOtherClass and have the handler be init.
HERE IS SOME UPDATED CODE
For your MyOtherClass:
public function MyOtherClass():void {
if(stage){
init(); //if stage is ready, call init, if not wait for the added to stage event
}else{
addEventListener(Event.ADDED_TO_STAGE,init);
}
}
public function init(e:Event = null):void {
removeEventListener(Event.ADDED_TO_STAGE,init);
for(var i:int=0; i<6; i++) {
var myMC:MyMovieClip = new MyMovieClip;
myMC.name = "myMC" + i; //setting the name so I can reference this movieclip after it's been added to stage
myMC.y = myMC.height * i + 20;
myMC.x = 20;
myMC.alpha = .7;
addChild(myMC); //!!!! add to the displayList
}
dispatchEvent(new Event(MyOtherClass.MOVIECLIPS_ADDED)); // just to be safe, let's dispatch a custom event when all movieclips have been added
}
public function traceEnabled():void {
var myMC:MyMovieClip = this.getChildByName("myMC1") as MyMovieClip; //!!! cast it as MyMovieClip so you have access to all the properties/methods in that class
if(myMC){ //myMC will be null if the cast failed
trace(myMC.isEnabled);
}
}
/*
getChildByName is slow and cumbersome. Most people generally only use it for accessing things put on the timeline in the Flash IDE. Using events is a much better way of accessing your items. If traceEnabled was caused by a mouse event attached to myMC, then this would be a much better implementation:
*/
public function betterTraceEnabled(e:Event):void {
var myMC:MyMovieClip = e.currentTarget as MyMovieClip;
if(myMC){
trace(myMC.isEnabled);
}
}
AND YOUR DOCUMENT CLASS:
public class DocumentClass extends MovieClip {
public var myOtherClass:MyOtherClass;
public function DocumentClass():void {
if(stage){
onAddedToStage(null); //most of the time stage is already populated in the constructor of your document class
}else{
addEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
}
}
public function onAddedToStage(e:Event):void {
myOtherClass = new MyOtherClass(); // upon instantiation, init is called in MyOtherClass and all of my movieclips are added to the sage
addChild(myOtherClass); //add it to the displayList
}
}