UsingTraits

Traits.scala

class UsingTraits

//refer notes 1,2,3

trait Friend{
  val name:String
  def listen()=println("Your friend "+name+" is listening")
}

class Human(val name:String) extends Friend

class Man(override val name:String) extends Human(name)

class Woman(override val name:String) extends Human(name)

// refer notes 3 and 4
class Animal

class Dog(val name:String) extends Animal with Friend


object UsingTraits extends Application{
  override def main(args:Array[String])
  {
    println("======================================================")
    println(traitNotes)
    println("======================================================")
    println("Logic execution strace below")
    println("======================================================")
    val ketan = new Human("ketan")
    ketan.listen
    val dog = new Dog("pluto")
    dog.listen


  }

  def traitNotes() =
  {
"""
  1. A trait is a behavior that can be mixed into or assimilated into class hierarchy.
  2. A trait is like an interface with partial implementation
  3. The vals and vars you define and initialize in a trait get internally implemented in the classes that mix the trait in.
  Any vals and vars defined but not initialized are considered abstract, and the classes that mix in these traits are
  required to implement them
  4. When class is not extending any other class; one can mix trait using "extends"  keyword; otherwise use "with" keyword.
  Check above example. 'Dog extends Animal with Friend'
  5. "Selective mixins" : Not all pets are friendly. So we can mix trait 'Friend' ONLY with the instance of 'friendly' pet.
   e.g. Lets assume cat with the name 'ruby' is friendly. so add 'Friend' trait for cat instance with
   name 'ruby' It can be done as  => new Cat('ruby') with Friend
"""

  }

}