IPSWAYS Scala Meetup - OO

OO.scala

  // object orientation
  trait Player
  case class EmptyPlayer() extends Player
  case class NamedPlayer(name: String) extends Player
  case class Score(p1: Int, p2: Int)

  // Vorteil case class: toString, hashcode, copy, == vs. eq
  val scoreA = Score(1, 2)
  scoreA.toString()
  scoreA.hashCode()
  scoreA.##

  scoreA.copy()
  val scoreB = scoreA.copy(p2 = 123)
  
  // == Prüft Objekt-Gleichheit
  scoreB == scoreA

  scoreA == Score(1, 2)

  // eq prüft referentielle Gleichheit
  scoreA eq Score(1, 2)

  val scoreC = scoreA
  scoreA == scoreC
  scoreA eq scoreC

  // Companion object -> singleton, factory methoden bzw. statische unitilities
  object MatchHolder {
    class Match(player1: Player, player2: Player, score: Score) {
  	    // Option
	    def getWinner: Option[Player] = {
        // Pattern Matching
	      score match {
	        case Score(s1, s2) if s1 > s2 => Some(player1)
	        case Score(s1, s2) if s1 < s2 => Some(player2)
	        case _ => None
	      }
	    }
	    
	    override def toString() = s"Match(${player1}, ${player2}, ${score})"
	
	  }
	  
    // companion object
	  object Match {
	  
	  	def apply(player1: Player, player2: Player, score: Score) = new Match(player1, player2, score)
	    def apply(score: Score) = new Match(EmptyPlayer(), EmptyPlayer(), score)
	  }
	  
  }
  
  import MatchHolder.Match
  
  // Neues Match über Konstruktur
  val match1 = new Match(NamedPlayer("Timo"), NamedPlayer("Jan"), Score(2, 5))
                           
  // Neues Match über Factory Methode 1
  val match2 = Match(Score(2,3))
  
  // Neues Match über Factory Methode 2
  val match3 = Match(NamedPlayer("Timo"), NamedPlayer("Jan"), Score(4, 5))
  
  // get or else default value
  val winner2 = match3.getWinner.getOrElse(EmptyPlayer())
  
  // Pattern Matching mit Klassen
  winner2 match {
    case NamedPlayer(name) => s"And the winner is ${name}"
    case EmptyPlayer() => "No player won the match."
    case _ => "Illegal input"
  }