trouble accessing non-static functions from static functions in AS3

Question

I have a class containing, among other things, a drop down menu. With the aim of saving space, and since the contents of the menu will never change, I've made a static DataProvider for the whole class that populates each instances menu. I was hoping to populate the list with actual functions like so:

tmpArr.push({label:"Details...", funct:openDetailsMenu, args:""});

and then assign tmpArr to the DataProvider. Because the DataProvider is static the function that contains that code also needs to be static, but the functions in the array are non-static. At first it didn't seem like a problem, because when the user clicks on a menu item the drop down menu can call a non-static "executeFunction(funct, args)" on its parent. However, when I try to compile, the static function setting up the DataProvider it can't find the non-static functions being passed. If the compiler would just trust me the code would work fine!

The simple solution is to just pass strings and use a switch statement to call functions based on that, but that's big, ugly, inelegant, and difficult to maintain, especially if something inherits from this class. The simpler solution is to just make the DataProvider non-static, but I'm wondering if anyone else has a good way of dealing with this? Making the static function able to see its non-static brethren?

Thanks.

Answer 1

OK, the basic reason for making things static is if you want to make it independant of an instance, for example the Math functions in as3 (you call Math.min() as opposed to var math = new Math(); math.min()...) this is useful for reference, repetetive calculation, simple actions (add 10 to x value) etc.

the problem with combining static and non static functionality is that when calling a static function, there is a possibility that the class has no instance at that point, or (in this case) that there is any reference to the function that would make sense in compilation (if a seperate class called the function, how would it reference openDetailsMenu?).

what you need to do is either go through getting function by name (object"functionname" works for example), make annonymous functions in your array or alternatively add a callback method to your static function something similar to this:

public static function doAction(object:Menu, event:String){
    if(event == "details") object.openDetailsMenu() ;
}

all in all you are just adding layers of complexity that isnt really going to help. if you just add a class function and get them all to do the same action it is not taking more space or effort than if you are calling to a static function. you need to think about how and why the function is going to be used in (or out of) the class.

Answer 2

you could just store a static reference to the instance, in this case _instance. ( Kind of like a ghetto singleton ) just be careful not to call the static method before the class has been instantiated.

/// in your constructor define a static reference handle to the instance
public function ClassName(){
   _instance = this;
}

public static function doSomethingStatic(){
   var varValue = ClassName._instance.someInstanceVariable;
}