How can I address a script I don't know the type of? - unity3d

Question

My game uses a variety of different game modes, and I'd like to spawn a different GameController script at the beginning of the scene depending on the game mode selected. Then other items (e.g., Enemies), would reference the main GameController, whether that be GameController_Mode1, GameController_Mode2, etc. But how can I have other objects referencing this if I don't know the type?
Unity iOS requires strict unityscript typing, so I can't use duck typing to get around this.

Answer 1

You can do this the same way you'd do it in C#, polymorphism. Derive all of your controllers from a single base Controller class. Then your GameController var can be set to any instantiation of a derived controller (see Start() in the example below).
Here is a quick example using a simple controller:
#pragma strict
var controller : MyController;
class MyController {
var data : int;
public function MyController(){
this.data = 42;
}
public function Print(){
Debug.Log("Controller: " + this.data);
}
}
class MyController1 extends MyController {
public function MyController1(){
this.data = 43;
}
public function Print(){
Debug.Log("Controller1: " + this.data);
}
}
class MyController2 extends MyController {
public function MyController2(){
this.data = 44;
}
public function Print(){
Debug.Log("Controller2: " + this.data);
}
}
function Start () {
controller = new MyController();
controller.Print(); // prints Controller: 42
controller = new MyController1();
controller.Print(); // prints Controller1: 43
controller = new MyController2();
controller.Print(); // prints Controller2: 44
}
I'm making any assumption that your gamecontrollers share function names and that the only difference is the code in each function.
[Update]
Regarding Heisenbug's comment below: You can use GetComponent to get the base class controller if your controller is a component.
Baseclass(BaseController.js):
class BaseController extends MonoBehaviour{
public function Print(){
Debug.Log("BaseController");
}
}
Extended class(Controller1.js):
class Controller1 extends BaseController {
public function Print(){
Debug.Log("Controller1: " + this.data);
}
}
Test:
var controller : BaseController;
controller = gameObject.GetComponent("BaseController"); //.GetComponent(BaseController) also works
controller.Print(); // will print "Controller1" if actual attached component is a Controller1 type

Answer 2

While it looks like there are some good answers already but it is worth mentioning Unity's SendMessage system. It is a really simple approach if all you need to do is call functions on the other object SendMessage.
http://docs.unity3d.com/Documentation/ScriptReference/GameObject.SendMessage.html
In short you can use the following syntax:
TargetGameObject.SendMessage("targetFunction", argument, SendMessageOptions.DontRequireReceiver);
You can also use SendMessage to call javascript functions from C# scripts or vice versa.