Factory method

Question

Hey all, I am tying to learn factory method and working on an example from the Oreilly AS3 Design patterns book. I am attempting figure out how all the classes work together in this design pattern and I have a question I am hoping someone might be able clearify for me.
In the document class "Main"  I have the following code in the constructor
// instantiate concrete shape creators
var unfilledShapeCreator:ShapeCreator = new UnfilledShapeCreator( );
// draw unfilled shapes  NOTE: draw() is a method of the ShapeCreator class
unfilledShapeCreator.draw(UnfilledShapeCreator.CIRCLE, this.stage, 50, 75);
I get what is going on there, so I open up the 'UnfilledShapeCreator" class and it has the following:
package shapecreators
     /* Concrete Creator class */
     public class UnfilledShapeCreator extends ShapeCreator
          public static const CIRCLE :uint = 0;
          public static const SQUARE :uint = 1;
          //implement the createShape factory method from the ShapeCreator Class.
          override protected function createShape(cType:uint):ShapeWidget
               if (cType == CIRCLE)
                    trace("Creating new circle shape");
                    return new CircleWidget( ); //Instantiates circleWidge Product Class
               } else if (cType == SQUARE) {
                    trace("Creating new square shape");
                    return new SquareWidget( ); //Instantiates square Widge Product Class
               } else {
                    throw new Error("Invalid kind of shape specified");
                    return null;
and the ShapeCreator class is as follows
package shapecreators
     /* Defines the abstract interface for the creator classes */
     import flash.display.DisplayObjectContainer;
     import flash.errors.IllegalOperationError;
     // ABSTRACT Class (should be subclassed and not instantiated)
     public class ShapeCreator
          public function draw(cType:uint, target:DisplayObjectContainer, xLoc:int, yLoc:int):void
               var shape = this.createShape(cType);
               shape.drawWidget( );
               shape.setLoc(xLoc, yLoc); // set the x and y location
               target.addChild(shape); // add the sprite to the display list
          // ABSTRACT Method (must be overridden in a subclass)
          protected function createShape(cType:uint):ShapeWidget
               throw new IllegalOperationError("Abstract method: must be overridden in a subclass");
               return null;
My question is: how does the cType  parameter get passed into the createShape method?  This method does not seem to get called from anywhere or any other class.   I see how FilledShapeCreator.CIRCLE gets passed to the  draw method in the ShapeCreator class, but the createShape method is never called like the draw method is.
Is it because createShape is called within the draw function?
I am quite sure it is a simple answer, but it has me completely lost.
Thanks,

Answer 1

Yes, it is called by super class in line:
var shape = this.createShape(cType);
By the way, I don't know where you got code but it is a pretty bad practice not type variables. Good compiler should not even allow you to compile. The line above should be:
var shape:ShapeWidget = this.createShape(cType);