Accessing the Document class in AS3

Question

How can instantiated classes access the Document class?

Even after I name the Document class using the Properties bar in Flash, attempting to access it from other classes usually fails, saying "attempting to access an undefined property...

One solution is always casting the Document class to itself! eg.

Main(Main).globalMethod();

But sometimes even this stellar gotcha fails, and then there's usually no way out, apart from the obvious!

class Other{

   var parentClass:Main;
   public function Other(parent:Main){
       parentClass = parent;            // pointer to the Main class in a local var!

       Main(parentClass).globalMethod();
   }
}

Answer 1

You can use a singleton for your document class (Main, in your example), which allows you to access the instance from anywhere.

public class Main extends Sprite {
    private static var _instance:Main;
    public static function get instance():Main { return _instance; }

    public function Main() {
        _instance = this;
       // etc...
    }

    // etc...
}

Then you access the Main instance like this:

public class Other {
    public function Other() {
        Main.instance.usefulInstanceMethod();
    }
}

The document class is a pretty good candidate for the singleton pattern, because generally there should only be instance available.