Question

I am using ActionScript3, I am writing a class that extends Bitmap, I want to have all of Bitmap’s behaviors and I also want to treat to replace its bitmapData with a subclass of bitmapData that offers more flexibility.

So basically what I have is(metaphor):

Class Gunman
{
    //Has-A
    public var pistol : Gun;
    public function Gunman(gun : Gun)
    {
        this.pistol = gun;
    }
    //methods
    public function shoot():void ..
    {
        pistol.fire();
    }  
}

Class Gun
{
    //constructor omitted cause it is unnecessary for this example
    public function fire():void ..
}

Now I extend these two classes.

Class Automatic extends Pistol
{
    override public function fire():void
    {
        super.fire(); super.fire(); super.fire();
    }
}

Class NavySeal extends Gunman
{
    public function Enforcer(auto : Automatic)
    {
        super(auto);
    }
}

The problem is that people can still easily do this:

var eliteSoldier : NaveSeal = new Enforce(new Automatic());
eliteSoldier.pistol = new Gun();

And this will be bad. Is there any way I prevent this?

I cannot change ‘Gunman’ cause it is part of the API.

Answer 1

If you are trying to prevent from changing public property public var pistol:Gun; than you can’t if you haven’t got the control over the class that has defined it. It is a bad design, it should be the getter/setter instead. Then you would be able to get and test what users are passing etc.

best regards