AS 2 + setInterval()

programming flash
1

In Actionscript 2 I cannot access global class variables in a method being executed by setInterval(). The variable can be accessed in other methods fine. The workaround is to pass the variable in as a parameter on the setInterval() function, but it seems I should be able to access it without doing that. Here is an example of what I am running in to:

class Food {
        private var drink:String = "Pepsi";
        private var interval:Number;
        // Constructor
        public function Food() {
                getDrink();
                interval = setInterval(allDrinks, 500);
        }
        private function getDrink() {
                // Returns "Pepsi"
                trace(drink);
        }
        private function allDrinks() {
                // Returns "undefined" instead of "Pepsi"
                trace(drink);
        }
}

I’d also like to note that I am using Flash player 8. Any help would be appreciated!