How do you share a variable between scripts using the MovieClip variable? - actionscript-3

Question

I'm currently trying to code an interactive timeline for my Uni project (keep in mind im a new coder) and we go over basic actionscript stuff. I was taught to communicate between scripts using a movieclip variable and declaring this.parent.
I have 3 scripts, one that controls the button that is used to move forward in the timeline, one is main, and the other controls the text box which displays the timeline. I placed a number variable in main, initialised at 0(timeCount). In the button script, i have it linked to main using refToMain, my movieclip variable. Within the button script, if the user clicks on the button, it rises the number variable from main using refToMain(refToMain.timeCount). It was my ambition to have the text box script track the number and each number has a different bit of the timeline on. However, when I trace timeCount in the button script, the number seems fine and raises accordingly, however it doesnt change the number in any other script. How can I fix this using basic as3 code?
In Main:
var timeCount:Number = 0;
In Button:
public function mDown (mDown:MouseEvent){
refToMain.timeCount += 1;
if(refToMain.timeCount >= 10){
refToMain.timeCount = 10;
}
trace(refToMain.timeCount);
In timeline:
if(refToMain.timeCount == 0){
timelineText.text = "welcome"
}
if(refToMain.timeCount == 1){
timelineText.text = "hello"
}

Answer 1

Are you expecting the code in your timeline to run continuously instead of just once? A frame script will only run once each time the timeline reaches that frame. And if you only have one frame, the timeline won't advance at all. If that's the case, a simple fix would be to add another frame to your timeline with F5, and then your timeline will alternate between your two frames forever so that your script on frame 1 will execute every other frame.
A better option would be to call the script that updates the timeline text directly every time the button is clicked. So you would move the code from your timeline script to your button script like this:
public function mDown (mDown:MouseEvent) {
refToMain.timeCount += 1;
if(refToMain.timeCount >= 10) {
refToMain.timeCount = 10;
}
trace(refToMain.timeCount);
if(refToMain.timeCount == 0) {
MovieClip(root).timelineText.text = "welcome";
}
if(refToMain.timeCount == 1) {
MovieClip(root).timelineText.text = "hello";
}
}

Answer 2

There are several ways and approaches to access objects and variables across your application.
1) Traversing. The (probably) older and the most straightforward one is fully understanding and controlling the display list tree. If you understand where your current script is and where your target script is, you just traverse this tree with root to go straight to the top, parent to go level up and getChildByName or [] or dot notation to go level down.
Pros: it's simple. Contras: The weak point of this approach is its inflexibility. Once you change the structure of display list tree, the access would presumably be broken. Also, this way you might not be able to access things that are not on the display list. Also, there are cases the dot notation would not work, and there are cases getChildByName would not work. Not that simple, after all.
2) Bubbling events. These are events that bubble from the depths of display list to the root. Mouse events are bubbling: you can catch it anywhere from the deepest object that had some mouse event then all its parents right up to the stage. You can read about them here. So, you can send bubbles from whatever depth you want then intercept them at the any parent of the event target:
// *** TextEvent.as class file *** //
package
{
import flash.events.Event;
public class TextEvent extends Event
{
static public const TEXT_EVENT:String = "text_event";
public var text:String;
// Although it is not a very good practice to leave the basic Event
// parameters out of it, but it will do for this example.
public function TextEvent(value:String)
{
// Set type = "text_event" and bubbles = true.
super(TEXT_EVENT, true);
text = value;
}
}
}
// *** Button script *** //
import TextEvent;
// Dispatch the event.
dispatchEvent(new TextEvent("welcome"));
// *** Main timeline *** //
import TextEvent;
// Subscribe to catch events.
addEventListener(TextEvent.TEXT_EVENT, onText);
function onText(e:TextEvent):void
{
// Extract the passed text value.
timelineText.text = e.text;
}
Pros: it is good in an app architecture terms. Contras: you cannot catch the bubbling event at the point that is not parent of event source.
3) Static class members. Or singleton pattern, its basically the same. You can devise a class that shares certain values and references over the whole application:
// *** SharedData.as class file *** //
package
{
import flash.display.MovieClip;
public class SharedData
{
static public var MainTimeline:MovieClip;
}
}
// *** Main timeline *** //
import SharedData;
// Make root accessible from anywhere.
SharedData.MainTimeline = this;
// *** Button script *** //
import SharedData;
// You can access main timeline via shared reference.
SharedData.MainTimeline.timelineText.text = "welcome";
Pros: you are not limited by display list structure any more, you can also share non-visual instances this way, anything. Contras: careful with timelines, they tend to destroy and create timeline instances as playhead moves, so it is not impossible to end up with a reference to a removed object while timeline holds a new instance that is no longer shared.