Listen to any change in the values of an Object in Actionscript

Question

Hi All, I have an Object in actionscript which has a few dozens of properties each of which is defined to be bindable and has its own change event. I would like to listen to any changes made to this object without having to add a listener to all of its properties. Is there a way in actionscript using which I can listen to any change in the values of an Object ?

Thanks, -A

Answer 1

One way could be to call an objectChanged() function on each setter.

public function set property1(arg) : void{
    property1 = arg;
    objectChanged();
}

Edit: You could make the class implement IPropertyChangeNotifier

Answer 2

I don't think there is a way to listen to listen to an event without adding a listener. However, there is no reason you can't use the same listener function for ever event change. Adding the event listeners should be relatively trivial:

myObject.addEventListener('property1Changed',myChangeHandler) myObject.addEventListener('property2Changed',myChangeHandler)

etc... etc..

You could also have each property fire a generic change event in addition to the property specific change event. Although tedious, this should be an quick cut and paste job.

Answer 3

You can use the PropertyChangeEvent on a [Bindable] class to listen for any property changes. As long as you're using the get/set properties.

package
{

    [Bindable]
    public class Person
    {
        private var _firstName:String;
        private var _lastName:String;
        private var _age:Number;

        public function get firstName():String
        {
            return _firstName;
        }

        public function set firstName(value:String):void
        {
            _firstName = value;
        }

        public function get lastName():String
        {
            return _lastName;
        }

        public function set lastName(value:String):void
        {
            _lastName = value;
        }

        public function get age():Number
        {
            return _age;
        }

        public function set age(value:Number):void
        {
            age = value;
        }

        public function Person()
        {
            // empty constructor
        }

    }
}

Then, in your using class add the event listener.

        public var p:Person;

        private function addListener():void
        {
            p = new Person();
            p.addEventListener(PropertyChangeEvent.PROPERTY_CHANGE, onPropertyChange);
        }

        private function onPropertyChange(event:PropertyChangeEvent):void
        {
            trace(event.property + " " + event.kind + " " + event.oldValue + " " + event.newValue);
        }