CODEWITHSUNDEEP
scala
zamk
zamk

Reputation: 71

Class needs to be abstract error while using traits in scala

Here is the class along with trait that it extends to:

class Atom(var x: Double, var y: Double, var z: Double) extends AtomTrait{

  private var name: String = null 

  private var coords = Vector(this.x,this.y,this.z)

  def setCoords(x: Double, y: Double, z: Double){ 

    this.x = x 
    this.y = y 
    this.z = z

  }

  def getCoords = coords

  def setName(name: String){ this.name = name }

  def getName = this.name

}

trait AtomTrait {

  def getCoords

  def setCoords

  def setName(name: String)

  def getName: String 

}

I get an error of class Atom needs to be abstract, since method setCoords in trait AtomTrait of type => Unit is not defined

I thought my setCoords method returns Unit since it only assigns values to private variables. What am I doing wrong?

Upvotes: 1

Views: 1221

Answers (1)

Lee
Lee

Reputation: 144136

The signature for setCoords should be:

trait AtomTrait {
  def setCoords(x: Double, y: Double, z: Double)
}

If you need to different coordinate types you can make the trait generic:

trait AtomTrait[C] {

  def getCoords: C

  def setCoords(coords: C)
}

class Atom(var x: Double, var y: Double, var z: Double) extends AtomTrait[(Double, Double, Double)] {

  def setCoords(coords: (Double, Double, Double)) {
    coords match {
        case (x, y, z) => {
            this.x = x 
            this.y = y 
            this.z = z
        }
    }
  }

  def getCoords = (x, y, z)
}

Upvotes: 3

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