Calling a function inside another class

Question

I have the following two classes and can't seem to figure to figure out how to call a function in the top one from the bottom one. The top one get instantiated on the root timeline. The bottom one gets instantiated from the top one. How do I call functions between the classes. Also, what if I had another call instantiated in top one and wanted to call a function in the bottom class from the second class?
Thanks a lot for any help!!!
package
     import flash.display.MovieClip;
     public class ThumbGridMain extends MovieClip
          private var grid:CreateGrid;
          public function ThumbGridMain():void
               grid = new CreateGrid();
          public function testFunc():void
               trace("testFunc was called");
package
     import flash.display.MovieClip;
     public class CreateGrid extends MovieClip
          public function CreateGrid():void
               parent.testFunc();

Answer 1

kglad,
Although I agree that utilizing events the way you attempted in your suggestion is better for at least a reason of eliminating dependency on parent, still you code doesn't not accomplish what Brian needs.
Merely adding event listener to grid instance does nothing - there is no mechanism in the code that invokes callTGMFunction - thus event will not be dispatched. So, either callTGMFunction should be called on the instance (why use events - not direct call - in this case?), or grid instance needs to dispatch this event based on some internal logic ofCreateGrid AFTER it is instantiated - perhaps when it is either added to stage or added to display list via Event.ADDED. Without such a mechanism, how is it a superior correct way OOP?
Also, in your code in ThumbGridMain class testFunc is missing parameter that it expects - Event.
Am I missing something?
I guess the code may be (it still looks more cumbersome and less elegant than direct function call):
package
     import flash.display.MovieClip;
     import flash.events.Event;
     public class ThumbGridMain extends MovieClip
         private var grid:CreateGrid;
         public function ThumbGridMain():void
             grid = new CreateGrid();
             grid.addEventListener("callTGMFunction", testFunc);
             addChild(grid);
        // to call a CreateGrid function named cgFunction()
         public function callCG(){
             grid.cgFunction();
         public function testFunc(e:Event):void
             trace("testFunc was called");
package
     import flash.display.MovieClip;
     import flash.events.Event;
     import flash.events.Event;
     public class CreateGrid extends MovieClip
         public function CreateGrid():void
             if (stage) init();
             else addEventListener(Event.ADDED, callTGMFunction);
         // to call a TGM function
         public function callTGMFunction(e:Event = null):void
           // I forgot this one
            removeEventListener(Event.ADDED, callTGMFunction);
            this.dispatchEvent(new Event("callTGMFunction"));
        public function cgFunction(){
             trace("cg function called");
I think this is a case of personal preference.
With that said, it is definitely better if instance doesn't rely on the object it is instnatiated by - so, in this case, either parent should listen to event or call a function directly.