Pass variable reference into function, not by value

[bianster]

hi,

is there a way to pass the reference of a variable(a) into a function so that when a's value is changed in the function, the actual variable value is changed and not only the a in the function?

i have this code snippet below =>

//this code is on frame 1 of the main timeline
logoFaded = false;
function alphaFaded(obj, targ, speed, dir, flag){
    obj.onEnterFrame = function(){
        temp = obj._alpha + speed*dir;
        obj._alpha = Math.min(100,Math.max(temp,0));
        if(obj._alpha >= targ){
            if(flag !== undefined){
                flag = true;
                trace(flag);
            }
            delete this.onEnterFrame;
        }
    };
}

//this code is on frame 2 of the main timeline
//its purpose is to monitor the alpha tween carried out by alphaFaded()
_root.createEmptyMovieClip("logoFadeListener_mc", 1);
logoFadeListener_mc.onEnterFrame = function(){
    if(logoFaded == true){
        trace("Logo fade in complete...");
        gotoAndPlay("mainTransition");
        delete this.onEnterFrame;
        this.removeMovieClip();
    }
};
alphaFaded(_root.logo_mc, 100, 5, 1, logoFaded);
stop();

the variable "logoFaded" that's declared and initialised on frame 1 is being passed into alphaFaded() by value currently and only the variable "flag" is set to true.

i tried to attach a variable to logoFadeListener like this but it didnt work as well

_root.createEmptyMovieClip("logoFadeListener_mc", 1);
logoFadeListener.logoFaded = false;
alphaFaded(_root.logo_mc, 100, 5, 1, logoFadeListener.logoFaded);

[Crismo]

Flash always passes primitives by value, so the solution is to put it into an object.
This is what you tried to do whit the last attempt, but when you pass logoFadeListner.logoFaded to the function your parsing a Boolean value (primitive).
If it is to work you have to pars just logoFaderListner and then within your function ask for the variable.

var myobject  = {status:false}

//------- This is what you are doing -------------
function changeStatus(val)
{
    return val = true;
    
}

var mytest = changeStatus(myobject.status)
trace("Returnd value : " + mytest);
trace("Object value : " + myobject.status);

//-------- This is what you should try
function changeObjectStatus(obj)
{
    return obj.status = true;
    
}

mytest = changeObjectStatus(myobject)
trace("Returnd value : " + mytest);
trace("Object value : " + myobject.status);

By the way the variables parsed to the function “alphaFaded” are not within the scope of the onEnterFrame function of the Logo_mc.

[bianster]

hi Crismo,

thanks for the heads up! it worked after i wrapped logoFaded into an object and passed the object into the function

but 1 thing is, u mentioned that the alphaFade parameters are not scoped to the onEnterFrame handler, i tried to test that out with a trace of 2 parameters in the event handler and the values were correct...

[bianster]

Originally Posted by bianster

but 1 thing is, u mentioned that the alphaFade parameters are not scoped to the onEnterFrame handler, i tried to test that out with a trace of 2 parameters in the event handler and the values were correct...

hi Crismo,

i think i misunderstood u when u said that the function parameters were not scoped to the onEnterFrame handler. Did u mean that the parameters will not be unique to the event handler?

[Crismo]

Nah just my old OOP lessons that are interfering with the ”whimsical magical” ways of actionscripting.

Looking at it from a purly OO angle, the moviclip function should not be able to see the variables parsed to the alphaFaded function.
But then this is what I love about Actionscript, the possibility to cheat when your in a hurry .

I have given an example of the problem that bugs me with this kind of solution.
If actionscript had been consistent, the 2 functions should both have been able to access the parsed variables, but they are not.
It could of course bee some feature of anonymous inner classes / functions etc.
But since I don’t know for sure, I’m just going to write it up as a practical feature of actionscript

It’s really not that important as long as we can choose our self to be consistent or not.

function Test(b_mc,c,d)
{
    b_mc.onEnterFrame = function ()
    {
    trace("C : " + c);
    trace("D : " + d);
    }
}

Test(_root.my_mc,5,6);


//------------------------------------------------------

function Test_2(b_mc,c,d)
{
    b_mc.onEnterFrame = frameFunction;
}

function frameFunction ()
{
    trace("C : " + c);
    trace("D : " + d);
}

Test_2(_root.my_mc,5,6);