How do you update a variable within a class from another class?

Here's an example of one class instantiating another class and changing a variable, just using public for ease.

// Class A in a.as

package

{

     public class A

     {

          public var SomeNumber:Number = 100;

          public function A()

          {

          }

     }

}

// Class B in b.as that instantiates A and then changes SomeNumber

package

{

     public class B

     {

          private var aRef:A = new A(); // instantiate a new "A" in the variable "aRef"

          public function B()

          {

               // trace the initial value of SomeNumber

               trace(aRef.SomeNumber); // traces 100

               // set it to a new value

               aRef.SomeNumber = 500;

               trace(aRef.SomeNumber); // traces 500

          }

          // provide a public method to set the reference to A if desired, used below

          public function SetReference(ref:A):void

          {

               aRef = ref;

          }

     }

}

The tricky part comes in making sure you pass the "correct instantiated reference" to an object to the class that wants access to it. In this example the B class directly instantiates the A class and changes it.

However typically on a frame script on the timeline you'd instantiate A and B. Then instead of B instantiating A, you'd pass a reference of it.

e.g. frame script on the main timeline:

// init objects

var aRef:A = new A();

var bRef:B = new B();

// pass a reference of A to B using that SetReference() method above:

bRef.SetReference(aRef);

Now  you've passed a reference of A into B and B dutifully updated its instance of A. Now any other frame scripts affecting aRef will also affect the reference B has to it because you're not creating 2 separate A's. You're creating just 1 and using that single reference.

Confusing, I know, but read it a few times.