ParamType.scala

class Person(val name: String) {
  def greeting = "I am Person %s".format(name)

  override def equals(that: Any): Boolean = that match {
    case p: Person if p.name == this.name => true
    case _ => false
  }

  override def hashCode = 11
}

case class Worker (
  override val name: String,
  job: String
) extends Person(name) {
  override def greeting = "I am Worker %s".format(name)

  override def equals(that: Any): Boolean = that match {
    case w: Worker if w.name == this.name && w.job == this.job => true
    case _ => false
  }

  override def hashCode = 22
}


object Instance {

  def process(p: Person) = println(p.greeting)

  def personHash(p: Person) = p.hashCode

  def equalsColin(p: Person) = {
    val colin = new Person("colin")
    println("Equals Colin? %s".format(colin == p))
    println("ColinEquals? %s".format(p == colin))
  }

  def main(args: Array[String]){
    val colinWorker = Worker("colin", "coder") 
    process(colinWorker)

    println("colinworker hash code: %d".format(colinWorker.hashCode))
    println("personHash for colin worker: %d".format(personHash(colinWorker)))

    equalsColin(colinWorker)
  }
}

Instance.main(Array.empty[String])