Unknown Identifier while using function?

Question

In player.hx:

public function new(X, Y, _upKey:String, _downKey:String){
    super(X, Y);

makeGraphic(20, 20, FlxColor.RED);

immovable = true;
}

In PlayState.hx:

override public function create():Void
{
    super.create();

    add(new Enemy(300, FlxG.height - 20, 10, 20));
    add(new Enemy(500, FlxG.height - 40, 10, 40));

    add(player = new Player(60, FlxG.height - 40, "UP", "DOWN"));
}

It returns to me with the errors "Unknown identifier: upKey" and "Unknown identifier: downKey" in the Player.hx file, even after I already set those in the function. How do I fix this?

Answer 1

Function arguments are only available in that particular function (this is known as the scope of the variable) - so just because your constructor has arguments named upKey and downKey, that doesn't mean you can also automatically use them in another function like update().

To be able to do that, you need to save the arguments to member variables of the Player class:

class Player extends FlxSprite
{
    var upKey:String;
    var downKey:String;

    public function new(X, Y, upKey:String, downKey:String)
    {
        super(X, Y);
        this.upKey = upKey;
        this.downKey = downKey;
    }

    override public function update():Void
    {
        super.update();
        trace(upKey, downKey);
    }
}