//合成模式--模拟建图
class Graphics {
    function draw() {
    }
}
class Line extends Graphics {
    function draw() {
        trace("line");
    }
}
class Rect extends Graphics {
    function draw() {
        trace("rect");
    }
}
class Circle extends Graphics {
    function draw() {
        trace("circle");
    }
}
class Pictures extends Graphics {
    private var _index:Number = 0;
    private var _pic:Object;
    public function draw() {
        for (var i in _pic) {
            _pic[i].draw();
        }
    }
    public function addGraph(g:Graphics) {
        _pic[_index] = g;
        _index++;
    }
    public function removeGraph(g:Graphics) {
        for (var i in _pic) {
            if (_pic[i] == g) {
                delete _pic[i], g;
                _index--;
            }
        }
    }
    public function set obj(o:Object) {
        _pic = o;
    }
}

var p1:Pictures = new Pictures();
var o1=new Object()
p1.obj=o1
p1.addGraph(l1=new Line());
p1.addGraph(r1=new Rect());
p1.addGraph(r2=new Rect());
p1.addGraph(c1=new Circle());
p1.draw();
trace("/////");
p1.removeGraph(l1);
p1.draw();
trace("/////");

var p2:Pictures = new Pictures();
var o2=new Object()
p2.obj=o2
p2.addGraph(l2=new Line());
p2.addGraph(r2=new Rect());
p2.draw();
//output
circle
rect
rect
line
/////
circle
rect
rect
/////
rect
line