Custom Event Listener not working - actionscript-3

Question

I am new to as3 and I recently saw creation of custom events in as3 in a tutorial and I wanted to incorporate in my game. When i did the tutorial, it all seemed well for that project. But it doesnt seem to work with the new project.
Here is my code :
package
{
import flash.display.MovieClip;
import flash.utils.Timer;
import flash.events.TimerEvent;
public class FashionFrenzy extends MovieClip
{
public var Buyer_mc:Buyer;
public var Buyers:Array;
public var gameTimer:Timer;
public function FashionFrenzy()
{
GameTimeController();
GenerateBuyers();
addEventListener(ReachMallDoorEvent.CHECK, OnReachMallDoor);
}
public function GameTimeController()
{
gameTimer = new Timer( 25 );
gameTimer.start();
}
public function GenerateBuyers()
{
Buyers = new Array ;
Buyer_mc = new Buyer(533.2,0) ;
addChild(Buyer_mc);
gameTimer.addEventListener( TimerEvent.TIMER, BuyerEnter );
if(Buyer_mc.y==377.25)
{
dispatchEvent( new ReachMallDoorEvent( ReachMallDoorEvent.CHECK ) );
}
}
public function BuyerEnter(event:TimerEvent)
{
Buyer_mc.Enter();
}
public function OnReachMallDoor(event:ReachMallDoorEvent)
{
trace("my timer starts now");
}
}
}
Here, OnReachMallDoor never seems to run because there is something wrong. I cant see the output saying "My timer starts now". But there is no error in the code and output doesnt show any runtime errors either. Where have I gone wrong? I want OnReachMallDoor function to run when my y coordinate is in desirable position and the event is dispatched.

Answer 1

The order of commands is wrong.
GenerateBuyers();
addEventListener(Rea...
The first line of these two is the one that could potentially cause the Event to be dispatched. But only after that will you start listening for it. That's simply too late. You have to start listening before the Event is dispatched.
The probability of the Event to be dispatched is very low.
Buyer_mc.y==377.25
Checking floating point values for equality is often not a good idea. It could easily be just slightly off due to rounding errors etc. If this .y property was controlled by the mouse for example, you'd have to position the mouse at exactly that position, which is very unlikely.
You only dispatch the Event at the beginning.
GenerateBuyers();
That function is only called once. The .y position is evaluated.
This only happens once and never again.
But the .y position is subject to change and the condition should be evaluated again, which doesn'T happen
The structure is not helpful.
It doesn't make much sense for an object to listen for its own Events. Simply call the function and be done with it.
Events are for communication between objects.
How this is supposed to be:
The point of the custom Event is to be notified about something.
You want to be notified when this condition
Buyer_mc.y==377.25
is true.
If you are evaluating that condition the way you do it now, then there's no point in receiving a notification about the result thereof. You have it already.
Instead, Buyer_mc should dispatch the Event. The condition should be checked in Buyer class.
What the code looks like
some snippets pointing out what the above means, code untested:
class Buyer
override public function set y(value:Number):void
{
if (value == 377.25)
dispatchEvent(new ReachMallDoorEvent(ReachMallDoorEvent.CHECK)); // I'm at the position, I send out the notification
super.y = value;
}
class FashionFrenzy
buyer = new Buyer(533.2, 0); // variables should start with small letter
buyer.addEventListener(ReachMallDoorEvent.CHECK, OnReachMallDoor);
If you now set the .y position to the value, the object will dispatch the Event. It will figure that out on its own.
Letting the object figure something out on its own and just receive a notification about it is the main reason to use custom events.