Actionscript 3 - Assign global variables inside function

Question

I have an AS3 function that runs when a URLRequest fails. I need to be able to use this function to assign global variables that I can then check against using other functions. How do I assign global variables inside of a function?

Thanks!

Edit:This is the variable (soundFile2Exist) I am trying to get outside of my function:

function onIOError(e:IOErrorEvent):void 
{

    var soundFile2exist = null;
    trace (soundFile2exist);
}

I am not using my code inside of a packge. Is there still a way to do this?

function playMusic(evt:MouseEvent):void
{
    channel = myMusic.play(songPosition);
    if (soundFile2exist != null) {
          channel2 = myMusic2.play(channel.position);
    }
    myTimer.start();
    btnPlay.mouseEnabled = false;
    trace (soundFile2exist);

}

I am strongly opposed to the entire premise of this question, that you would want to pass data between functions using global variables. — jhocking
– jhocking, Commented Sep 11, 2011 at 19:50
There are many ways of sharing data between functions that do not involve global variables. Global variables are pretty much the worst way of accomplishing that task. — jhocking
– jhocking, Commented Sep 11, 2011 at 19:56
Your statement that "I am not using my code inside of a package" suggests to me that you don't know how to do object-oriented programming. AS3 is a strongly object-oriented language, so I suggest learning about that. — jhocking
– jhocking, Commented Sep 11, 2011 at 20:03

Lars Blåsjö · Accepted Answer · 2011-09-11 20:13:49Z

4

If your code is "not in a package" (like in a frame script on a timeline), any variables you declare on the same level, same scope, as your functions will be accessible to the functions in that scope, so you could do something in the lines of this:

var soundFile2exist;

function onIOError(e:IOErrorEvent):void {
   soundFile2exist = null;
}

function otherFunction():void {
   trace (soundFile2exist);
}

In other situations, static variables of a class can be used in place of global variables.

edited Sep 11, 2011 at 20:13

answered Sep 11, 2011 at 19:58

Lars Blåsjö

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4 Comments

user547794 Over a year ago

Hmm... I tried this and it looks and the 2nd trace returns "undefined" rather than "null"

Lars Blåsjö Over a year ago

Sorry, there was an error in my example code, I had "var soundFile2exist = null" in the onIOError function, making it a local variable to that function. I edited the example, now it should work better.

jhocking Over a year ago

upvote because this is the best answer to the question, but I don't recommend this way of programming. Timeline code is almost always a bad idea (AS2 was even worse in this regard because it required it; at least with AS3 you don't have to put code on the timeline).

jayarjo Over a year ago

Is there any way you can access such variables by name in variable? Like globals['soundFile2exist'] = null or something?

Myk · Accepted Answer · 2011-09-11 19:30:06Z

1

The most common approach is to create a Singleton class which you can then reference from anywhere. This basically sets up a class where the only way to get access to an instance of that class is via a controlled static method that returns one and only one instance. So whenever you say MySingleton.getInstance() you always end up with the same object.

Grant Skinner has a quick writeup of how to implement a Singleton in AS3: http://gskinner.com/blog/archives/2006/07/as3_singletons.html

answered Sep 11, 2011 at 19:30

Myk

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3 Comments

jhocking Over a year ago

The obvious solution to problems with your code not being in a package is to put it in a package. Is there some reason why you can't do that?

jhocking Over a year ago

Incidentally, I don't want to down-vote this answer because I used to use Singletons occasionally, but I've learned a lot about the downsides of Singletons and once I started using dependency injection I found I never needed Singletons at all.

Myk Over a year ago

Sure, but someone asking this question is probably not at a point where impleneting dependency injection would be non-trivial. This seemed better than to simply say "Create a class with all-static methods." ;)

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