Scalaのトレイトで馬（と陸上走者）を表現してみた

TraitSample.scala

package tmp

trait Sex {def getSex: String}
trait Male extends Sex {def getSex = "牡"}
trait Female extends Sex {def getSex = "牝"}

trait Distance {def getDistance: String}
trait Sprinter extends Distance {def getDistance = "短距離"}
trait Middler extends Distance {def getDistance = "中距離"}
trait Stayer extends Distance {def getDistance = "長距離"}

trait RunType {def getRunType: String}
trait Nige extends RunType {def getRunType = "逃げ"}
trait Senkou extends RunType {def getRunType = "先行"}
trait Sashi extends RunType {def getRunType = "差し"}
trait Oikomi extends RunType {def getRunType = "追込"}
trait Kyokutan extends RunType {
  abstract override def getRunType = "大" + super.getRunType
}

trait SpecialName {def getSpecialName: String}

trait Medalist {def getMedalName: String} // XXX Runnerクラス内が適切？


abstract class Horse extends Sex with Distance with RunType {def getName: String}
abstract class SpecialHorse extends Horse with SpecialName {def getGICount: Int}
class NaritaBrian extends SpecialHorse with Male with Stayer with Sashi {
  def getName = "ナリタブライアン"
  def getGICount = 5
  def getSpecialName = "シャドーロールの怪物"
}
class SilenceSuzuka extends SpecialHorse with Male with Middler with Nige with Kyokutan {
  def getName = "サイレンススズカ"
  def getGICount = 1
  def getSpecialName = "ススズ"
}
class SakuraChitoseoh extends SpecialHorse with Male with Middler with Oikomi with Kyokutan {
  def getName = "サクラチトセオー"
  def getGICount = 1
  def getSpecialName = "太氏ね"
}
class HaruUrara extends Horse with Female with Sprinter with Senkou {
  def getName = "ハルウララ"
}

abstract class Runner extends Sex with Distance with RunType {def getName: String}
class NaokoTakahashi extends Runner with Female with Stayer with Sashi with SpecialName with Medalist {
  def getName = "高橋尚子"
  def getSpecialName = "Qちゃん"
  def getMedalName = "金"
}
class UsainBolt extends Runner with Male with Sprinter with Senkou with SpecialName with Medalist {
  def getName = "ウサインボルト"
  def getSpecialName = "ライトニングボルト"
  def getMedalName = "金"
}


object TraitSample {

  def main(args: Array[String]) {
    debugHorse(new NaritaBrian)
    debugHorse(new SilenceSuzuka)
    debugHorse(new SakuraChitoseoh)
    debugHorse(new HaruUrara)

    debugRunner(new NaokoTakahashi)
    debugRunner(new UsainBolt)
    debugRunner(new UsainBolt with Kyokutan)
  }

  private def debugHorse(horse: Horse) {
    println("==========")
    println(horse.getName)
    println(horse.getSex)
    println(horse.getDistance)
    println(horse.getRunType)
    if (horse.isInstanceOf[SpecialHorse]) {
      val sh: SpecialHorse = horse.asInstanceOf[SpecialHorse]
      println(sh.getSpecialName)
      println(sh.getGICount)
    }
  }

  private def debugRunner(runner: Runner) {
    println("==========")
    println(runner.getName)
    println(runner.getSex)
    println(runner.getDistance)
    println(runner.getRunType)
    if (runner.isInstanceOf[SpecialName]) {
      println(runner.asInstanceOf[SpecialName].getSpecialName)
    }
 }
}

• 性別・距離適性・脚質はHorseとRunnerで共通の属性、「横断的なタグ」としてトレイトを使ってみた
• コップ本でいうところの「積み重ね変更なトレイト」で、極端な脚質を表現してみた