Accessing properties via a String in AS3 - actionscript-3

Question

I have an engine I created a while back that loads objects into a container based on XML data. A really quick example of the XML would be like this:
<level>
<object cname="enemies.Robot">
<pos x="200" y="400" layer="mobiles" />
</object>
<object cname="Player">
<pos x="12" y="89" layer="mobiles" />
</object>
</level>
I have a class Environment that has a method loadLevel(data:XML) which I parse the XML through, then the function runs through the XML finding all object nodes and uses getDefinitionByName to determine which Object I want to create based on object.#cname.
From here, I have to manually define each property based on the XML like so;
obj.x = xml.pos.#x;
obj.y = xml.pos.#y;
etc.
I was wondering if there's an inbuilt method for setting a property based on a String. By this I mean something like so:
var mc:MovieClip = new MovieClip();
mc.someInbuiltFunctionThatSetsAProperty("alpha", 0.5);
This way I could change my XML to be more like so:
<object cname="Player">
<props>
<x>200</x>
<y>221</y>
<alpha>7834</alpha>
<health>Something</health>
<power>3</power>
</props>
</object>
And iterate through all the children of props to set all of my properties on the fly.
I know if I create an Object and set properties within it like so:
var obj:Object =
{
var1: "hello",
var2: "there",
name: "marty"
};
That you can then iterate through names/values using the for(String in Object) loop like this:
var i:String;
for(i in obj)
{
trace(i + ": " + obj[i]);
}
/**
* Output:
* var1: hello
* var2: there
* name: marty
*/
Is there maybe something even similar to that?
Surely there's a way, as here's an example of identifying a property using a String:
var ar:Array = [new MovieClip(), new MovieClip()];
ar.sortOn("alpha", Array.ASCENDING);
So just to make my question more to-the-point: I want to be able to get and set properties that I can identify using a String.

Answer 1

Why not using ["string property"] notation :
var mc:MovieClip=new MovieClip()
mc["alpha"] = 0.5 // setter
var alpha:Number=mc["alpha"] // getter

Answer 2

I'm not quite clear on what it is you're looking for exactly, but I have a general sense of what you're getting at and have a few suggestions for you. First, have a look at the documentation for the Object class in the AS3 Language Reference. Look specifically at the propertyIsEnumerable() and setPropertyIsEnumerable() methods. I think that's what you're asking about.
If not, you might want to look into the behavior of dynamic classes, which let you add variables to an object on the fly.