Call function in creating class

Hi All,
I have “class A” that makes a bunch of objects from “class B”

class A

public function classA(){    
            for(var i:int = 1; i<=num; i++) {
                var b:classB = new classB(i);

public function checkOverlap() {
            trace('checkOverlap has been called');

I need to call a function in “class A” from “class B” but I’m not sure how to do that.

class B

public function stoppedMoving() {
         // check for overlap in "class A" here.