So being new to AS3 but not development in general, during a recent project that I just started I hit an immediate snag where my normal method of OOD is causing errors in AS3.
I created a layer in Adobe Flash called code just to keep everything separate and in frame one under actions I used the following code to get started:
var GameContainerSize:int = 400;
class GameInfo {
var GameID:int;
var HomeTeam:String;
var VisitingTeam:String;
function GameInfo()
{
}
}
This simple code immediately causes an error though
Scene 1, Layer 'Code', Frame 1, Line 4 1131: Classes must not be nested.
And my best guess is this is because the timeline and all code on it exists within a class already. So what should I be doing if I want to develop this program using class objects, or is this even possible in flash?
You can't define classes on the timeline. Each timeline is exported as a class, var and function declarations become members of the class, and frame code is moved to its own frame functions which are called when the timeline reaches that frame. Thus the error is saying "you can't put a class in a class" because the timeline already is a class.
To define classes you must use external .as files with package blocks:
// GameInfo.as
package {
public class GameInfo {
public var GameID:int;
public var HomeTeam:String;
public var VisitingTeam:String;
public function GameInfo(){ }
}
}
In Flash Pro you can link a class to a timeline (document or symbols). Such a class must extend Sprite or MovieClip.
You can also refer to any of your classes from any frame script. For example, you could put on frame 1 of your main timeline:
var gameInfo:GameInfo = new GameInfo();
Typical OOP would involve using external .as class files for almost everything, with only minimal function calls on your timeline frames, like stop() at the end of a timeline or calling a custom function you've added to the class linked to the timeline.
I created a layer
That's not ideal. The problem is that it will not get you any closer to understanding the code, because it isn't code. It's a feature of the flash authoring environment. You might as well spend a day with the drawing tool drawing something.
to keep everything separate and in frame one under actions
Organisation is important, but layers aren't the way to go. As each class definition goes into its own external file, you have to create additional files anyway if you want to create more classes. And you want to create more classes because having only one is horrible object oriented design. Being consistent here is important. That's why people in the comments suggested to use a document class and have no code on any frames. All code is organised in classes. No exceptions1.
Having said all that, I highly advice against using Adobe Flash to learn As3. There's too much obfuscation going on behind the scenes. If you want to learn how to code As3, use a code editor. (or plain text editor + compiler if you prefer). Learning what settings dialog has to be adjusted in order to get what you want is not going to get you any closer to understanding OOD in As3.
I also see package, is this kind of like a namespace and does it need to be named, if not what is its purpose?
No, packages are packages and namespaces are namespaces. Apples and oranges.
Packages are used to organize classes just like a structure of
folders is used to organize the .as fiels of those classes. In fact,
the package is pretty much exactly that folder structure, for example:
flash.display is for all display related classes
flash.events is for events
A namespace allows you to control access to members of a class. Namespaces are very rarely used in As3. Here's an article from grant skinner about namespaces. Personally, I never needed to use namespaces. If you are jsut getting started, you can very well ignore them for now.
That sounds perfect! except I cannot get it to launch on my Win10 machine. I may just end up outsourcing this at this ratio
flash develop is the alternative editor. It's free, fast and lightweight.
my normal method of OOD
You want to extend your definition of normal with
always explicitly specify the access control modifiers
member names start with small letters
public class GameInfo {
private var gameID:int;
private var homeTeam:String;
private var visitingTeam:String;
function GameInfo()
{
}
}
1admittedly, there are top level functions that are pretty much free floating functions without a class. If you want to do oop, this is not what you want. It's for the occasional independent utility function. Stick to classes for now.
Related
I am trying to get started with Document class in AS3 with Flash CS4.
There is some existing code in the timeline, but for now I've been trying to write just the new code in the Document class.
I have used classes and functions like URLRequest, Event, navigateToURL, ContextMenu etc in the timeline directly without importing them explicitly. And this works.
Once I associated the document class, by keeping the above mentioned code in the timeline frame itself, compilation errors were thrown for the mentioned classes. I had to import them - in timeline or in the Document class - for the code to compile correctly.
What is the fundamental difference here, which enables timeline code to access these classes directly without importing? Can this be done while having a Document class also?
For reference, my Document class basic code looks like this:
package
{
import flash.display.MovieClip;
public class Main extends MovieClip { }
}
Document classes need to have import statements. Infact, for the most part timeline code does too; I can't seem to be able to get any timeline code to work with the classes you listed without the appropriate imports.
It's worth saying that explicit imports are a good thing; they allow you to manage your code and more understand where any potential savings can be made. For the most part flash (or your IDE of choice) will do them for you if you use auto-complete (Ctrl + Space in Flash).
There are ways to avoid certain imports via class paths, but really, I would bite the bullet and just use import statements.
I want to create a re-usable Flash MovieClip (component maybe?) that can be dragged and dropped from the library onto the Flash IDE stage (for an example, a "stop all movieclips timer component").
I've created some attractive vector icon graphics for visual reference, so that when it's dragged onto the stage, the developer can visually see the component on the stage, similar to what Google does with it's DoubleClick components. It's not important for these icon graphics to be seen at runtime however, and I'd like their visual portions to not be compiled at runtime to save on filesize.
I'm often asked to create visually rich Flash units in extremely small file sizes. So basically I want my movieclip icon components to not add to filesize (except for the code portion), not compile and render visually but still have the code within them run.
How can I achieve this? Would creating them as components do anything for my issue? Is this even do-able?
Components are definitely the best way to achieve visually represented imported code, however it would be much easier, more compatible and more reliable to just use an imported code library...
Make a seperate .as file, put it in com/mycompany/animation in your swf folder (or use a global classpath), and add this code:
package com.mycompany.animation {
class MyTimerUtils {
public static function stopAllClipsAfterTime(ms){
setInterval(MyTimerUtils.stopAllClips, ms);
}
public static function stopAllClips(){
//etc
}
}
}
Then when you want to use it in a project, just put this code on frame 1 of your main timeline:
import code.mycompany.animation.MyTimerUtils;
MyTimerUtils.stopAllClipsAfterTime(3000); // 3 seconds
What could be easier? If another developer wants to know if a piece of code is implemented they need only look at the first few lines of code.
I've worked around this with a hack for now, but would rather know if there's a right way to do it. I have a function that churns out MovieClips, which are tiles for a map that I then attach to the stage. It determines which class of tile to use based on a string variable, like this:
// symbolID holds our class name, determined by logic above
var newClass:Class = getDefinitionByName(symbolID) as Class;
var newtile:MovieClip = new newClass();
This works, but only if an instance of the class already exists somewhere else in the code. It could be anywhere-- in the document class, in some buried function of a helper class, it doesn't seem to matter. If not, Flashdevelop throws error 1065, "Variable (the variable) is not defined". I mention that I'm using Flashdevelop because it seems like it might be compiler-specific, but I'm not sure.
My hack fix is to do this:
var a:baseTile;
a as anotherTile;
a as aThirdTile;
and so on, which works, but definitely isn't ideal if I'm going to have hundreds of these tile classes eventually.
Edit: I should add that these movieclips are coming from a .swc file, which comes from Flash Professional.
You have to use the 'hack'.
getDefinitionByName() can only work with classes that exist at runtime. Unfortunately, if you don't make use of a class, it won't be compiled and won't exist at runtime.
Library symbols make getting around this a little easier. If you check the box that has them available automatically at a given frame, you can just make sure your getDefinitionByName() calls are done during or after that frame.
While SWC libraries can include specific classes to include in the build path, Flash compiler will not link unreferenced classes to a SWF; therefore, requires a linkage library.
Example linkage to retain classes:
/** linkage library */
private static const classA:ClassA;
private static const classB:ClassB;
private static const classC:ClassC;
Another option would be to load the classes from a RSL (Runtime Shared Library).
Basically yes, you need to have a strict reference of that class somewhere in your code. You can even make that reference "unreferenced" elsewhere. I have a hundred of classes like this, and I had to make a single Array of these classes, located somewhere inside the project. I have placed it aside the function that calls getDefinitionByName() to make sure the classes are available in that function.
private static const dummy:Array=[Rock01, Rock02,...,Gem01,Gem02,...];
So you can use such an Array listing all your tiles that you have in your project and want to be accessible by getDefinitionByName().
I have been writing a game in timeline code. I want the different frames (rooms) in the game to be able to share information between each other. Of course, timeline code is limited to the frame it is written in.
After doing quite a bit of reading ("Foundation Game Design with Flash" and a number of articles, tutorials, forums etc) I decided to employ a document class. This did not work either. It seems it only works for frame one but not the rest of the frames (I have four).
How can I have frame four respond to something that happpened in frame one? For example, if the player achieves something in frame one, I want a movie clip in frame four to be visible.
If You are writing your code on the timeline, My suggestion would be to create two layers in the timeline, one for 'frame-actions' - in this layer you insert the code specific to a single frame (will work when the movieclip is stopped on that particular frame).. And also create one more layer called global-actions (for the entire timeline). Only the first frame will be a key frame and there should be empty frames till the end of the timeline.
In this layer actions write the code that you want to access from any keyframe in the same timeline.
If you define a variable in the actions which are written for the whole timeline (global-actions) then that will be available on all the frames.
Now if you want to go to a different frame based on some action, just write some functions in the layer which contains global actions and call that particular function through the frame actions. To go to a different frame use the 'gotoAndStop(frameNumber)' function of flash.
I want to tell you that while it will work, I would not recommend using it in this way.
HTH.
You can use static variables - these are variables which are linked to a class, rather than an instance of it.
Suppose your document class was called Document.as, and you wanted a variable, playerLives, to be visible from any part of the program.
Declare it inside Document.as:
public static var playerLives:int = 3;
You can then reference this directly from anywhere else in your code with:
Document.playerLives
(note that the variable is a member of the class itself, not an instance of it).
You could use a dedicated Statics class to hold these variables if you want to keep your document neat, or attach them to the relevant classes (eg Player.lives)
I've not used timeline/frames for some years but I believe this is how I used to do it!
NB Statics will be fine for your purposes but they are, in some ways, an equivalent to the _global variable in AS2 (at least, they can be used in the same manner) - many would not approve of their use, or over-use, as they are freely accessible from anywhere in your program (thus anathema to the OO concept of encapsulation), but personally I try not to worry about it in small cases - the most important thing to know about the rules of any design pattern is when they can be broken!
They are also slightly slower to access than instance members, but you won't notice this unless you are constantly accessing/changing them (making things like player velocity, which will need to be referenced/changed every frame, static, is not a good idea).
Hope this helps.
You may find the simplest way to link everything with the document class is to move your four frames into a movieclip together and have that on the first frame, then interact with that movieclip.
E.g. in the document class, where the movieclip instance on the timeline is called 'game'.
game.gotoAndStop(4);
game.objectToDisplay.visible = true;
If you encounter reference errors in the IDE then you can avoid these by using [] notation to refer to the properties of game, e.g. game["objectToDisplay"].visible = true;
Note that it's not really best practice to do this, but it will at least help you to finish that first game which is really more important at this stage in your learning. Afterwards, if you want to learn more then I'd recommend "The Essential Guide to Flash Games" by Jeff Fulton from 8bitrocket.com - it will teach you how to use the document class effectively.
I am having trouble incorporating graphical assets created in Flash with my Haxe code.
In the Flash IDE, I've created a symbol with the linkage name "MySprite". I compile this into assets.swf. I know that to use symbols in this .swf from my Haxe code, I need to add the following option when using the Haxe compiler:
-swf-lib assets.swf
I'd now like to write a class called "MySprite" which is associated with this symbol, like so:
class MySprite extends Sprite {
public function new() {
// ...
}
}
Basically, I'd like to achieve something similar to the technique presented in this tutorial:
package {
import flash.display.*;
[Embed(source="assets.swf", symbol="MySprite")]
public class MySprite extends Sprite {
public function MySprite() {
// ...
}
}
}
It's unclear from the Haxe documentation whether this can be done, or what the syntax is for doing it.
I think so, but I'm not sure, Haxe doesn't override classes from assets.swf with the classes you declared. There was a discussion about it on the mailing list (the old one, not in the Google groups), and this was the decision... I don't know why this decision was made.
You could still do it with SamHaxe. At least back in the days I was able to. Unfortunately, SamHaxe was abandoned, and if there are bugs or something not working as you need it - you are pretty much on your own. The good thing about Sam is that it's relatively small project. It's written in Haxe and I was able to build it from sources.
You could also try: http://code.google.com/p/hxswfml/ The project seems to be functional and the author used to reply to users. It might be a tad more complex though. I'm quite sure it was possible to do, but you will probably need to ask the author / figure it out yourself.