objects follow the same class - arrays

Question

I have a problem, I am working on a larger project, and I made a small project to test this problem.
The problem being:
I have made a button which spawns enemy's. When an enemy hits allyCopy it bounces back in the opposite direction. But the problem is that EVERY instance of enemy bounces back when a single one hits the test object.
My code:
my main class:
package {
import flash.display.*;
import flash.ui.*;
import flash.events.*;
public class MainClass extends MovieClip {
public var speed:int = 3;
public static var enemyArray:Array = [];
public var randNumber:Number = 0;
public static var allyCopy1 = new allyCopy();
public function MainClass() {
stage.addEventListener(Event.ENTER_FRAME, update);
spawnButton1.addEventListener(MouseEvent.CLICK, spawnEnemy);
allyCopy1.addEventListener(MouseEvent.MOUSE_DOWN, dragOn, true);
allyCopy1.addEventListener(MouseEvent.MOUSE_UP, dragOff, true);
addChild(allyCopy1);
allyCopy1.x = 60,25;
allyCopy1.y = 208,05;
}
public function update(e:Event)
{
/*for (var i:Number = 0; i < enemyArray.length; i++)
{
enemyArray[i].x -= speed;
}*/
}
public function dragOn (e:MouseEvent)
{
allyCopy1.startDrag();
trace("drag");
}
public function dragOff (e:MouseEvent)
{
allyCopy1.stopDrag();
}
public function spawnEnemy(e:MouseEvent)
{
randNumber = Math.random();
trace(randNumber);
var enemy1 = new enemy ();
addChild(enemy1);
enemyArray.push(enemy1);
if (randNumber <= .5)
{
enemy1.x = 526.25;
enemy1.y = 68.05;
} else
{
enemy1.x = 526.25;
enemy1.y = 200.05;
}
}
}
}
The enemy class:
package {
import flash.display.*;
import flash.events.*;
public class enemy extends MovieClip {
public static var hp:int = 100;
public static var speed = 3;
public function enemy() {
addEventListener(MouseEvent.CLICK, killEnemy);
addEventListener(Event.ENTER_FRAME, update);
}
public function update (e:Event) {
x -= speed;
if ( x <= 0)
{
MainClass.enemyArray.pop();
trace(MainClass.enemyArray);
}
if(MainClass.allyCopy1.hitTestObject(this))
{
speed = -3;
}
}
public function killEnemy (e:MouseEvent)
{
this.parent.removeChild(this);
trace(MainClass.enemyArray);
MainClass.enemyArray.pop();
}
}
}

Answer 1

Well the problem is that speed is static variable. This means that it's not separate for each enemy, but it's common (shared) for all instances. So if you change it, it changes everywhere..
Don't do variables static that often - it's pretty bad practice. The very same thing will happen with life - if you decrease the life of one enemy, it will decrease the life of all enemies (all instances of that class).