User Guide

Object.watch() 389

var speedWatcher:Function = function(prop, oldVal, newVal, speedLimit) {

// Check whether speed is above the limit

if (newVal > speedLimit) {

trace ("You are speeding.");

}

else {

trace ("You are not speeding.");

}

// Return the value of newVal.

return newVal;

}

// Use watch() to register the event handler, passing as parameters:

// - the name of the property to watch: "speed"

// - a reference to the callback function speedWatcher

// - the speedLimit of 55 as the userData parameter

myObject.watch("speed", speedWatcher, 55);

// set the speed property to 54, then to 57

myObject.speed = 54; // output: You are not speeding

myObject.speed = 57; // output: You are speeding

// unwatch the object

myObject.unwatch("speed");

myObject.speed = 54; // there should be no output