How do I create a instance of a class using a variable? - actionscript-3

Question

I am trying to pass a variable to a method in one of my Classes so I can use it to create the correct movieClip (image)
My Class code looks like this:
package {
import flash.display.MovieClip;
import flash.display.Sprite;
public class SlideShow extends MovieClip{
public function SlideShow()
{
//does something on start
}
//This function should take the string and use it as the class name below.
public function addImages(BackGround:String):void
{
trace(BackGround);
var main_bg:BackGround = new BackGround();
addChild(main_bg);
}
}
}
and when I call the method from my maintimeline it looks like this:
var shoeSlide:SlideShow = new SlideShow();
shoeSlide.addImages("menPant");
SO "menPant" is acually the name I assigned to a class of a movieclip that has some images in it.
I am getting the following error:
SlideShow.as, Line 30 1046: Type was not found or was not a compile-time constant: BackGround.

Answer 1

make sure you import getDefinitionByName at the top of your class code if flash doesn't do it for you automatically. This should work.
public function addImages(BackGround:String):void
{
var symbol_class:Class = getDefinitionByName(BackGround);
//EDIT: removed data type :BackGround -- this will give an error.
var main_bg = new symbol_class();
addChild(main_bg);
}