What I showed you works, and is more flexible than just a whole bunch of if statements, it's just that you can't reference the Class using just 'this'
you have to put a 'hard' reference to the Class constructor somewhere or use getDefinitionByName.
//can't do that without first calling getDefinitionByName to get the Class definition.
//for example -
var class:Class = flash.utils.getDefinitionByName("className");
var someThing:Array = [1,2,3,4];
var two:Number = this["someThing"];
//this will work however, just not with Classes.
In your case however, you also want to limit your need of if statements, so the object with Class names in it is an ok option vs getDefinitionByName.
yep, I hit submit for this post, then saw Henkes reply, he is correct of course.