As someone that works in training for a very tough field (Nuclear Power). I found your article to be extremely refreshing and useful for this topic. I have been doing a lot of flash development recently and started only a month ago not knowing what a tween was. To now making much more complex Javascript calls and using xml to dynamically run different scenarious (pictures, text videos, sound) at points in time. I really need to separate my stuff into classes and have been looking for answers. You have done a phenomenal job at delivering. BTW, to all you eggheads, the correctness of the information IS important although how you get there IS not. So Ryan KUDOS and ty.

Or get a two-button mouse – “ctrl” in OSX == “Command” for most Windows functions, there is a control button on the new keyboards too :)

Go back to Part 1 of the series and set up your file so that your document class is called Main. Just as the Dog.as class is paired with the Dog MovieClip in your library, the Main.as class is paired with your main swf movie (remember that your Flash main timeline is just one big MovieClip).

When you write those two lines of code to instantiate an instance of the Dog class and add it to the display list, those lines of code go in your Main class’s constructor function (or wherever). So Main, the main movieclip (your main timeline) creates an instance of Dog called “dog” (the Dog Movieclip gets paired up with the Dog .as file and they become one). Then Main places that instance in its display list, so that it gets drawn to the screen.

Yeah?

I know its been forever since this article was written, but as this is one of the few ‘fresh start’ tutorials for AS3 out there, I feel that expressing my problem here would be met with the most ‘user-friendly’ answer.

As I attempted to link the “Dog.as” to the Flash project by typing it into the “Document Class: ___” area, an error message appeared saying, “You must specify a unique class name that is not associated with any library symbols.” This error message also appears when I have already loaded the Dog.as file and attempt to name the Linkage of a Movie Clip to “Class: Dog”. I have looked around the Internet for a solution, and found advice saying to rename the “Class” names to unique names, but to keep the “Base Class” names the same. I have found this information a bit useless considering how knowledgeable of Flash I am. I appreciate any help you can give me on this subject and also thank you for getting me started on my way to understanding and using AS3 like a real egghead.

The code is an example in Colin Moock’s “Essential ActionScript 3.0″ that i am using to learn AS3. The instruction says it should run. Because I am new to AS3, I don’t what and how to define to get the code run.

If you’ve got the code on frame 1 of the timeline, change the last line to:

addChild(group);

var rect1:Shape = new Shape();
rect1.graphics.lineStyle(1);
rect1.graphics.beginFill(0x0000ff, 1);
rect1.graphics.drawRect(0, 0, 75, 50);

var rect2:Shape = new Shape();
rect2.graphics.lineStyle(1);
rect2.graphics.beginFill(0x0000ff, 1);
rect2.graphics.drawRect(0, 0, 75, 50);

rect2.x = 50;
rect2.y = 75;

var group:Sprite = new Sprite();
group.addChild(rect1);
group.addChild(rect2);

someMainApp.addChild(group);

Thanx in advance for your assistance.

sbliss

http://en.wikipedia.org/wiki/Sam_(dog)

Nevertheless I still find the tutorials in here very good and I tend to recommend it to my fellow colleagues which are trying to make a lift off in the world of AS3. Thanks again for the huge effort in making these tutorials.

Thx once again and yes, take much encouragement. Your explanations are a breath of fresh air.

When you compile (test/build your movie, hit CTRL+Enter – whatever you want to call it), and your swf runs, the interpreter is the part of the Flash Player that reads all of your AS1/AS2/AS3 code instructions and does what you tell it to do (hopefully).

If you write your code on the first frame of the main timeline, the interpreter knows that’s one of the first places to look for code. It starts at the top of that code, and starts chewing through it.

But if your code all exists in external .as Class files, how does the interpreter know where to start? It doesn’t! So we have to TELL it where to start.

So in that little field labeled “Document Class” (which is a very unhelpful way they’ve decided to name it), picture instead that it says “START HERE”. You type in the name of the Class where you’d like the interpreter to START looking at your code.

The Eggheads call this your program’s “point of entry”. Hang on to that term – if you branch out to other languages, you’ll see it crop up again from time to time.

Does that help?

Now that we’re writing everything in separate .as Class files, we need to declare permissions for everything. i mentioned in Part 1 that we’d be declaring everything “public” until we understood what that was all about.

And, incidentally, public/private is what Part 4 of the series is all about!

- Ryan

There’s no rule saying that you have to be perfect at this from square one. Don’t listen to the eggheads – that’s what they’ll have you believing. Remember in math class when they made you go through a bunch of problems like 7+7+7+7 before they taught you multiplication, just to show you that there’s a better way? i find the best way to approach learning OOP is to charge in and make your mistakes. There’s plenty of time to hone your technique.

And in an upcoming Understanding Classes post, i’ll show you one or two ways to cheat and speed things up. It’ll make the eggheads crap their pants. Good fun.

- Ryan

Waaahh! Adobe ruinzed my Flashs!!! If XML navigation weren’t sooo much better in AS3 I probably wouldn’t even bother.

private function iCannotBeInvokedFromOutsideThisClassBecauseIAmPrivate():void
{
}

We’re going to get into private vs public in a future tutorial, but why not get a sneak peek? If you were to drop the piece of code above into a Class, and then you instantiated the class and tried to call the function, you’d get an error. The function is defined as private, and is inaccessible outside the Class.

Am i misunderstanding you?

One tiny detail: functions are all public. A quirk of AS3 that is a result of them running out of time when they were writing it. (Straight from Colin Moock… he wrote the book, after all.) I wouldn’t mention it except it really helped me understand why I kept getting segments of the “magazine” where the page turns would suddenly malfunction. Understanding that every function is public helped me resolve this.

Keep it coming, Ryan. You rock!

- Ryan

Please post the relevant source code here: http://www.untoldentertainment.com/boards/viewtopic.php?f=8&t=180 (I hope you don’t mind, Ryan?)

I’d post my email, but I know the interwebz bandits are -just- around the corner. And they scare me.

Would be happy to poke at your code — kaolin [a]^t erif{.org}

- Ryan

I do have a problem that I’m struggling with still. I’m using the Flex SDK with Flash Develop to make my code, and I simply can’t figure out how to get things in my classes to show up on the stage/canvas/whatever.

I did wrap it in a UIComponent, but i can’t get it to show up. If i strip the AS3 code for making a circle off of the main.mxml page onto an external class, in this case being MakeCircle.as, I can’t get it to show up on the display no matter what i do.

I don’t think you are a flex guy, but if you can help, I’d be happy to paste the code.

Thanks for your help.

- Ryan

Are you familiar with the educational kids’ show The Magic Schoolbus? They have tons of ridiculous, innaccurate stuff throughout the episode just to keep the story moving along, and they devote the last five minutes of the show to a scripted call-in segment where “viewers” phone them up to tell them what they got wrong.

So this is all very much in the spirit of The Magic Schoolbus … but thank you for your clarification! It’s a good extra credit point to study.

- Ryan

I didn’t want to be an egg-head, but you’ve forced me to… =’(

An object and a class are two very separate things, and IMHO the distinction between them is an important concept in order to avoid confusion in the future (how come Dog.bark() doesn’t work!?), especially if you start to throw in static methods/variables. An object is what contains the methods and variables, the class is what defines exactly what methods and variables an object has. Although I’ll admit it does get a little confusing when you realize that flash stores Classes AS Objects…

Other than that, it was a good tutorial, and to offset my egg-headedness, I’ll say that I thought all your other inaccuracies were justified by the scope and target audience of the tutorial.