addEventListener to a Variable

programming flash
1

Hi

I have a variable

var pageState:uint = 0;

The only values of that variable will be 0 (ZERO) and 1 (ONE).

I need to set a kind of Event Listener. Each time the variable changes:

if (pageState == 0){
x = 10;
}else{
x = 0;
}

How can I set an addEventListener to this?

Thanks