AS3 class / base class constructor

Question

A follow-up to my previous question.

I have a button on my stage, which has a class called Game1 (I didn't define this class, just linked it like Juan answered to my other question). The button has 'GameButton' as base class, which at the moment contains some simple x, y statements.

All my buttons will have a dummy class 'GameX' and a base class of GameButton; this way they inherit from the base class, but they can still have a different graphic.

I have a main class which contains code to add this button:

public class MainAteam extends MovieClip
{
    public var btn1:Game1;

    public function MainAteam()
    {
        btn1 = new Game1();
        addChild(btn1);
        btn1.addEventListener(MouseEvent.CLICK, startGame1);
    }
    // startGame 1 function here
}

Now, I would like to be able to give x, y values through parameters so I can place each button on a different spot. However, when I try new Game(5,5) and I put the following in the GameObject constructor:

package 
{
 import flash.display.SimpleButton;

 public class GameButton extends SimpleButton
 {
    public function GameButton(startX:Number, startY:Number)
    {
        x = startX;
        y = startY;
    }
  }
}

I get the following error:

1203: No default constructor found in base class GameButton

I don't really know how to fix this, since I let Flash define the GameX classes for me (I suppose they're just empty) and use the base class to set some properties. If I just put x=5; y=5, it works fine. Thanks a lot.

score 3 · Accepted Answer · 2011-03-20 21:20:11Z

3

This is one of two things, either you need to call super(); from within your constructor, or you havn't implemented required class properties/methods on initialization. Try extending Button, not SimpleButton see if that works better for you.

EDIT My first answer was on the right track but still wrong. The problem is that you're creating your Game1, Game2 etc classes and not calling the constructor of the GameButton class. When you extend a class that has REQUIRED constructor arguments you must provide them using super(); So in this case, inside your Game1 class constructor you need to call:

super(positionX, positionY);

OR

You can modify your GameButton constructor to have default values, like so:

public function GameButton(var x:int = 0, var y:int = 0)

In case you don't know, super() is just a way to access the constructor of the base class, which can also be called the super class, which is why the method is called super :). Hope this helps.

ALSO

Also please note that if you're creating these Game1, Game2 classes etc from within the Flash IDE (in the library) then you're going to need to go the route of adding default values to the GameButton constructor as Flash automatically generates classes for library objects. Alternatively, you can still create the graphics in precompiled library clips, and instead of defining a class + base class in the Export For Actionscript settings, create an actual Game1/Game2 etc class manually like you did for GameButton, and then in the Export For Actionscript area put the full qualified class name. Like so:

enter image description here

edited Mar 20, 2011 at 21:20

answered Mar 20, 2011 at 21:14

user562566

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8 Comments

Joris Ooms Over a year ago

What I did now is put btn1.x =, btn1.y = in my Main class (my game class) but I'm not sure if this is good practice. I'd rather send it to the constructor with parameters. The problem I see with this is that I let Flash generate those Game1, Game2 classes, which I'm not actually using. I can't put super(); there (I suppose it'd go there). Still confused :(

user562566 Over a year ago

I just updated my answer a few times lol to explain it all. Anymore questions feel free to ask.

user562566 Over a year ago

Yeah I posted more nfo about what to do in that situation, also explaining how it all works/what it means. You have 2 options (there are more but to keep it simple), basically create and use those classes yourself (hand-coded) or add default values to the super class constructor.

user562566 Over a year ago

I'm not quite sure what you mean by:"That way, I could put the buttons (who got Game1, Game2, .. classes) on the stage with just one constructor". If you did that, and didn't manually change/set the position(s) after instantiating the classes, they would all be piled on top of each other. If you want them to all start out in a pre-destined, unique position you're not going to be able to do it this way. You'll have to manually set the position of each item one way or another.

user562566 Over a year ago

I'd just eliminate the base class, allow flash to generate the classes for Game1 etc, and when you instantiate them just set the position. Like var p:Game1 = new Game1(); p.x = 10; p.y = 100; etc.

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