CODEWITHSUNDEEP
c#oopinheritanceunity-game-engineconstructor
ScottishTapWater
ScottishTapWater

Reputation: 4786

Derived Class Constructor Returning Null

I am creating a chess game, in my code I am generating objects to represent the pieces.

These are all of type Pawn, Rook, King etc and are derived from the Piece class.

However, when I attempt to create a new Pawn as such:

return new Pawn(location, gameObj);

Despite the values of location and gameObj being valid, the returned value is null.

The (unfinished) Piece and Pawn classes are defined as such:

public class Piece : MonoBehaviour
{
protected Coord location;
protected bool isWhite;
protected bool specialUsed = false;

void displayMarkers(List<Coord> targets)
{

}

public void moveTo()
{

}

public void resetColour()
{

}

public virtual void displayTargets()
{

}
}

and:

public class Pawn : Piece
{
public Pawn(Coord loc, GameObject gameObj)
{
    location = loc;
    if (loc.y < 4) { isWhite = true; } else { isWhite = false; }     
}

public override void displayTargets()
{

}
}

Any help would be greatly appreciated as this has me completely stumped. Thanks!

Upvotes: 2

Views: 541

Answers (1)

aybe
aybe

Reputation: 16662

You are using Unity,

In Unity you cannot instantiate a MonoBehaviour using new Pawn(), you must do that through AddComponent<T> method.

As a result, parameterized constructors are useless.

Example:

var pawn = gameObject.AddComponent<Pawn();
pawn.isWhite = true;

See the documentation for more information:

http://docs.unity3d.com/ScriptReference/GameObject.AddComponent.html

Upvotes: 1

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