Toggling Boolean Problem

Question

this code is written in simple ActionScript, but i'm assuming this problem of mine would occur in all languages that have boolean datatypes.

i'm simply clicking the stage so that my boolean variable reverses its value and than traces/prints/logs it's new value. however, it's always tracing true instead of switching between true and false for each mouse click.

what am i doing wrong?

var myBool:Boolean;

stage.addEventListener(MouseEvent.CLICK, mouseClickHandler);

function mouseClickHandler(evt:MouseEvent):void
    {
    changeBoolean(myBool);
    }

function changeBoolean(boolean:Boolean):void
    {
    boolean = !boolean;
    trace(boolean);
    }

Answer 1

In the function changeBoolean, you're changing the value of the boolean (poor name, by the way - try to avoid naming collisions with built-in types, even with different casing) parameter. This has no effect outside that function.

You want to change the value of myBool (which I would call a class field in .Net or Java) instead.

function mouseClickHandler(evt:MouseEvent):void
    {
    myBool = !myBool;
    trace(myBool);
    }

...is what I would do (again, with a naive understanding of ActionScript).

Answer 2

You are passing a value to the function, not the reference. This means that boolean value inside your changeBoolean function is copied from myBool variable so when you changed it inside the function, it didn't realy change myBool variable. There are basically two solutions to this:

1. change the function to not accept parameters and inside it change myBool variable or
2. change the function so that it returns the boolean parameter and on calling the function, set the myBool valu to the result of the function