Actionscript: Am I deleting this class instance correctly? - actionscript-3

Question

Okay by deleting correctly I mean am I actually getting rid of the instance or is it just not being drawn anymore? I should mention that I'm trying to delete the instance from within its own class, that is it deletes itself. It 'works' in that the square it draws no longer appears on the screen but again I'm not sure if it's really gone or just not being drawn. Anyway here's the class:
package
{
import flash.display.*;
import flash.events.*;
public class OBJECT_bullet_1 extends Sprite
{
public var X:int = 0; public var Y:int = 0;
public var Y_SPEED:int = 5;
public var DEPTH:int = 9;
public var CONTAINER:Sprite = new Sprite();
public function CREATE(CONTAINER:Sprite,X:int,Y:int):void
{
this.CONTAINER = CONTAINER;
CONTAINER.stage.addEventListener(Event.ENTER_FRAME,STEP);
this.X = X; this.Y = Y;
DRAW();
}
public function STEP(event:Event):void
{
this.graphics.clear();
Y -= Y_SPEED;
if (Y < 20) {Y = 300; CONTAINER.removeChild(this); CONTAINER.stage.removeEventListener(Event.ENTER_FRAME,STEP); CONTAINER.(delete this); CONTAINER = null; return;}
DRAW();
}
public function DRAW():void
{
this.graphics.beginFill(0xCCCC00,1);
this.graphics.drawRect(X - 2,Y - 2,4,4);
this.graphics.endFill();
CONTAINER.addChild(this);
}
}
}
The part I'm concerned about is in the STEP function when it checks to see if Y < 20. You'll notice that it does several things afterwords. Am I deleting it correctly? If so is there anything I am doing to delete it that I don't need to?

Answer 1

Yes to both questions. To ensure an object is deleted, all you have to do is remove all references to it. The child reference and event callback are the only ones the above code is aware of, and you have taken care to remove them both. Nullifying your own container reference is unnecessary, as is whatever you think CONTAINER.(delete this) does.
There are some other significant problems with your supplied code. I made some improvements and heavily commented all changes to explain why I made them.
// You should avoid using the default package. Using the default package
// can make it difficult later on if you start having naming conflicts.
package com.stackoverflow.example {
import flash.display.Sprite;
import flash.events.Event;
import flash.geom.Point;
import flash.utils.getTimer;
// Class names are spelled in CamelCase by convention. Also, note
// that "Object" has a special meaning in AS3 so you should avoid
// using it to refer to anything else. I used here "Entity" instead.
public class EntityBullet1 extends Sprite {
// ALLCAPS when used are reserved for static const names.
// A good use of static consts is to store "magic numbers".
public static const DEFAULT_COLOR:uint = 0xCCCC00;
public static const DEFAULT_SPEED_X:Number = 0;
public static const DEFAULT_SPEED_Y:Number = -100;
public static const DEFAULT_SIZE:Number = 4;
// I'm calculating the time between frames for smoother movement.
public var lastTime:int;
public var color:uint = DEFAULT_COLOR;
public var size:int = DEFAULT_SIZE;
// Instead of separate x and y vars, you can use the Point class.
public var pos:Point;
public var speed:Point;
// Instead of a "create" method do all creation inside the constructor!
public function EntityBullet1(x:Number = 0, y:Number = 0) {
pos = new Point(x, y);
speed = new Point(DEFAULT_SPEED_X, DEFAULT_SPEED_Y);
// You don't need the parent container to access the ENTER_FRAME
// event. Every DisplayObject has its own. Much simpler.
addEventListener(Event.ENTER_FRAME, firstStep);
}
public function draw():void {
// Keep all drawing inside the draw function. Previously,
// clear() was being called inside the step method.
graphics.clear();
graphics.beginFill(color);
graphics.drawRect(pos.x - size/2, pos.y - size/2, size, size);
graphics.endFill();
}
// On the first frame, the field "lastTime" is still uninitialized.
// This method initializes it to the current time and hands off
// future events to the proper step() method.
public function firstStep(event:Event):void {
removeEventListener(Event.ENTER_FRAME, firstStep);
addEventListener(Event.ENTER_FRAME, step);
lastTime = getTimer();
step(event);
}
public function step(event:Event):void {
// To move at a fixed rate regardless of how fast the framerate is,
// you need to calculate the time delta.
var cur:int = getTimer();
var delta:Number = (cur - lastTime) / 1000.0;
lastTime = cur;
// Position equals velocity times time.
pos.x += speed.x * delta;
pos.y += speed.y * delta;
draw();
// Note that all DisplayObjects already have references to their
// parent containers called "parent"!
if (pos.y < 20) {
if (parent != null) parent.removeChild(this);
removeEventListener(Event.ENTER_FRAME, step);
}
}
}
}