class BuildingTypes
{
public static const CASTLE:Strint = "castle";
public static const HOME:String = "home";
//
public function BuildingTypes()
{
throw new IllegialOperationError("Класс является статическим!!!")
}  

var list:Vector.<IBuildingModel> = new Vector.<IBuildingModel>()
for each(var item:XML in xml.building)
{
var type:int = parseInt(item.attribute("type"));
var model:IBuildingModel;
switch(type)
{
case BuildingTypes.CASTLE:
model = new Castle();        // Нужная модель под тип castle
break;

case BuildingTypes.HOME:
model = new Home();        // Нужная модель под тип home
break;
}
model.init(item);
list.push(model);
}  

function get image():String;

class Castle implements IBuildingModel
{
private var _title:String;
private var _type:String;
private var _image:String;

public function Castle()
{

}

public function init(xml:XML):void
{
_title = xml.attribute("title");
_type= xml.attribute("type");
_image= xml.attribute("image");
}

public function get type():String
{
return(_type);
}

public function get title():String
{
return(_title);
}

public function get image():String     // Реализуем геттер для обращения к свойству image
{
return(_image);
}
}  

function someMethod(building:IBuildingModel):void
{
if(building is Castle)
{
var castle:Castle = building as Castle;
var image:String = castle.image;
}
}

var type:String = item.attribute("type");

import com.greensock.*;
import flash.events.MouseEvent;
import flash.events.Event;
import flash.geom.Point;

var wallz:Rectangle = wall.getBounds(this);
var wallzData = new BitmapData(wallz.width, wallz.height, true, 0);
wallzData.draw(wall);
   
var fishz:Rectangle = fish.getBounds(this);
var fishzData = new BitmapData(fishz.width, fishz.height, true, 0);
fishzData.draw(fish);

var old:Point = new Point(fish.x, fish.y);

fish.addEventListener(MouseEvent.MOUSE_DOWN, onDown);

this.addEventListener(Event.ENTER_FRAME, enterFrameListener);

function enterFrameListener(e:Event):void
{
  if(wallzData.hitTest(new Point(wall.x, wall.y),
                    255,
                    fishzData,
                    new Point(fish.x, fish.y),
                    255
   
                           ))
     {
   fish.x = old.x;
   fish.y = old.y;
   TweenMax.killTweensOf(fish);
  }
  else
  {
   old.x = fish.x;
   old.y = fish.y;
  }
}

function onDown(e:MouseEvent):void
{
  stage.addEventListener(MouseEvent.MOUSE_UP, onUp);
  stage.addEventListener(MouseEvent.MOUSE_MOVE, update);
}

function update(e:Event):void
{
  TweenMax.to(fish, 2 ,{x :mouseX, y: mouseY});
}

function onUp(e:MouseEvent):void
{
  stage.removeEventListener(MouseEvent.MOUSE_UP, onUp);
  stage.removeEventListener(MouseEvent.MOUSE_MOVE, update);
}