root/as2/Endflow/sample/KeyIf/Bullet.as

class Bullet {
        private static var tmr:Number;
        private static var bullets:Array;
        
        private static function register(bullet:Bullet):Void {
                if(bullets == null) {
                        bullets = new Array();
                        tmr = setInterval(function(){
                                for(var i = 0; i < bullets.length; i++) {
                                        if(bullets[i].tick.apply(bullets[i])) {
                                                bullets[i].dispose();
                                                delete bullets[i];
                                                bullets = bullets.slice(0, i).concat(bullets.slice(i+1));
                                        }
                                }
                                if(bullets.length === 0) {
                                        clearInterval(tmr);
                                        bullets = null;
                                }
                        }, 25);
                }
                bullets.push(bullet);
        }

        private var mc:MovieClip;
        
        public function Bullet(parent:MovieClip, init:Object) {
                this.mc = parent.attachMovie('bullet', 'bullet_mc_' + parent.getNextHighestDepth(), parent.getNextHighestDepth(), init);
                register(this);
        }
        
        public function tick():Boolean {
                return (this.mc._y -= 2) < -5;
        }
        
        public function dispose():Void {
                this.mc.removeMovieClip();
        }
}