Passing parameters to a trait

Question

I want to model the game of chess. For that, I want to make an abstract class, Piece which takes a player and a position as arguments. From that, I want to extend to other classes such as Pawn:

trait Piece(player: Int, pos: Pos) = {

  def spaces(destination: Pos): List[Pos]

}

case class Pawn extends Piece = {
//some other code
}

However, I think I'm not allowed to pass parameters to a trait, like this trait Piece(player: Int, pos: Pos).

So how can I have an abstract class Piece that has fields?

Answer 1

You could use an abstract class

abstract class Piece(player: Int, pos: Pos) {
  ...
}

case class Pawn(player: Int, pos: Pos) extends Piece(player, pos)

Or (probably better) you define those members abstractly in a trait

trait Piece {
  def player: Int
  def pos: Pos
  ...
}

case class Pawn(player: Int, pos: Pos) extends Piece