Dynamic app creation using MXML?

Question

I'm working on creating a small quiz application which will
be driven by pre-formatted external XML. I have designed various
custom question canvases for each of the question types (MCQ, short
answer, match-pairs etc.) and I'm wondering if there is some way to
implement the main application using MXML instead of ActionScript?
I've managed to hard-code the order of the questions, knowing
which canvases are needed in which order, but I need to be able to
detect the question type from the XML (that bit I can manage) and
then add the appropriate question canvas component in order in my
tabNavigator.
Essentially, I'm trying to replicate the function of a
switch:case clause in MXML. Does anyone know if this is possible?
I've started trying to implement it in ActionScript, but I'm a bit
of a newbie to AS3, and I keep getting errors I don't understand,
like "Access of undefined property" where I'm referring to an
object I've just declared and instantiated in the previous line of
code. E.g (anywhere I use mainPanel):
<mx:Script>
<![CDATA[
import mx.controls.Text;
import mx.containers.Canvas;
import mx.containers.Panel;
var mainPanel:Panel = new Panel();
Root.addChild(mainPanel);
mainPanel.layout = "absolute";
mainPanel.setStyle("left", 10);
mainPanel.setStyle("top", 10);
mainPanel.setStyle("right", 10);
mainPanel.setStyle("bottom", 10);
var testPage:Canvas = new Canvas();
var numQuestions:int = quizQns.childNodes.length;
var qTypes:Array = new Array(numQuestions);
var textLine:Array = new Array(numQuestions);
]]>
</mx:Script>

Answer 1

You can declare and initialize variables outside functions in
your script block, but for most else you need to do it in a
function. I would continue learning AS3 as it will give you real
flexibility and power.
<?xml version="1.0"?>
<mx:Application xmlns:mx="
http://www.adobe.com/2006/mxml"
creationComplete="init()">
<mx:Script>
<![CDATA[
import mx.controls.Text;
import mx.containers.Canvas;
import mx.containers.Panel;
private var mainPanel:Panel;
private var testPage:Canvas = new Canvas();
private var numQuestions:int = 10;
// private var numQuestions:int = quizQns.childNodes.length;
private var qTypes:Array = new Array(numQuestions);
private var textLine:Array = new Array(numQuestions);
public function init():void {
mainPanel = new Panel();
addChild(mainPanel);
mainPanel.layout = "absolute";
mainPanel.setStyle("left", 10);
mainPanel.setStyle("top", 10);
mainPanel.setStyle("right", 10);
mainPanel.setStyle("bottom", 10);
]]>
</mx:Script>
</mx:Application>