Reading class name as String

1

hey guys,

does anyone know how do i make a string as a classname.

Example:



var str:String = "Bubble";  // i have bubble class


//the below line doesn't work , it is just to 
//explain what i want. I have tried the call method also
var newCLASS = new [str+ "()"];   

//It should work like 
var newCLASS:Bubble = new Bubble();

Thanks!