Class implementation in TorqueScript. Base class member not accessible
by Andy Hawkins · in Torque Developer Network · 05/09/2012 (4:19 am) · 5 replies
I'm doing a tutorial on using OOP in TorqueScript and I have this example. Everything else works well except for the last example where I want the Parrot to access the mana attribute from the base class. It's doesn't - it's just blank. What's the correct way to make this happen?
new ScriptObject( Enemy )
{
health = 100;
hasSpecialAttack = false;
lives = 3;
mana = 10;
};
function Enemy::delete(%this)
{
echo("Parent deleted");
}
function Enemy::talk(%this)
{
echo("I am of type Enemy");
}
new ScriptObject( Enemy1 )
{
superclass = Enemy;
health = 20;
hasSpecialAttack = true;
lives = 5;
};
function Enemy1::delete()
{
echo("Child deleted");
parent::delete();
}
function Enemy1::talk(%this)
{
// example of overriding
echo("My parent is of type Enemy");
}
new ScriptObject( Parrot : Enemy1 )
{
superclass = Enemy;
health = 25;
};
function Parrot::talk(%this)
{
// example of polymorphism
echo("Wrrraarrkkk!");
}
$enemy1 = new ScriptObject( :Enemy1 )
{
class = Enemy1;
};
$enemy2 = new ScriptObject( :Parrot )
{
class = Parrot;
};
$enemy1.talk();
$enemy1.delete();
$enemy2.talk();
// easily modify only somethings of a new object
echo($enemy2.lives); // parrot has same lives as Enemy1 (parent)
echo($enemy2.health); // but has independent health
echo($enemy2.mana); // and gets mana from base class (Enemy) !!!!!! ONLY IT DOESN'T GET LOADED WITH ANYTHING
$enemy2.delete();
#2
05/09/2012 (8:01 am)
Yeah I was kinda hoping TorqueScript implied that instead of me having to type it. Seems a little less elegant. 
#3
In order for children to access parent class data fields they have to inherit them. Try changing the Enemy1 declaration to: new ScriptObject(Enemy 1 : Enemy)
Now, if you just want to access a parent class's data field in a child class Steve's method (or a simple <childClass>.superClass.<whatever>) will work.
05/09/2012 (9:27 am)
The issue is that 'Enemy1' is a child of 'Enemy' but doesn't inherit from 'Enemy'. If you try to echo($enemy1.mana); you'll get a blank return as well. In order for children to access parent class data fields they have to inherit them. Try changing the Enemy1 declaration to: new ScriptObject(Enemy 1 : Enemy)
Now, if you just want to access a parent class's data field in a child class Steve's method (or a simple <childClass>.superClass.<whatever>) will work.
#4
Error: cannot change namespace parent linkage of Enemy1 from Enemy to t2dAnimatedSprite.
05/10/2012 (3:59 am)
I have implemented it but it doesn't like classes to be linked with t2dAnimatedSprites. So how am I supposed to have classes then?new ScriptObject( Enemy )
{
health = 25;
hasSpecialAttack = false;
mana = 100;
lives = 1;
x = 0;
y = 0;
direction = 0;
};
new t2dAnimatedSprite(Bunny3) {
animationName = "EnemyStandAnimation";
canSaveDynamicFields = "1";
superclass = "Enemy";
class = "Enemy1";
Position = "-66.250 28.750";
size = "12.500 12.500";
CollisionActiveSend = "1";
CollisionPhysicsSend = "0";
CollisionPhysicsReceive = "0";
CollisionGroups = "1";
CollisionCallback = "1";
mountID = "15";
_behavior0 = "EnemyBehavior";
_behavior1 = "HealthBar offsetY -4 background healthRedImageMap foreground healthGreenImageMap";
_behavior2 = "SetScore score 150";
};Error: cannot change namespace parent linkage of Enemy from ScriptObject to t2dAnimatedSprite.Error: cannot change namespace parent linkage of Enemy1 from Enemy to t2dAnimatedSprite.
#5
What I would do is add another field to your Enemy class(es) that holds a reference to your t2dAnimatedSprites. Something like:
05/10/2012 (1:35 pm)
That sort of thing isn't possible in TScript. ScriptObjects aren't 'real' classes, they're more like namespaces so they have to be self-contained. What I would do is add another field to your Enemy class(es) that holds a reference to your t2dAnimatedSprites. Something like:
new ScriptObject(Enemy)
{
health = 25;
hasSpecialAttack = false;
mana = 100;
lives = 1;
x = 0; // may not be needed as you can access the Position field of the actual 2D object
y = 0; // same as above
direction = 0; // same as above?
// ### new field ###
animSprite = -1;
};
// create your t2dAnimatedSprite and pass in the id to this method
function Enemy::linkSprite(%this, %spriteObj)
{
%this.animSprite = %spriteObj;
} 
Associate Steve Acaster
[YorkshireRifles.com]
It works but seems somewhat excessive ...