[flexcoders] Loading component at runtime with out compile time linking

[Gireesh]

Hai, 
  
   I wanted to create module at run time using the below code

var cls:Class = getDefinitionByName("mx.controls.Button") as Class;
var comp:UIComponent = new cls();

Right now this is not possible unless I declare a dummy variable of a Button 
class in my program to get the compile time linking. 

My question is,  when I use Flex 3 framework cache, is it still required to 
link the components in compile time ? Will these components wont be available 
in Flex framework swz/swf ?

How can I resolve this ?

-Gireesh