Scala example source code file (bug603.scala)

This example Scala source code file (bug603.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

a, a, any, any, array, array, function0, susp, susp, test

The Scala bug603.scala source code

object forceDelay {
  class Susp[+A](lazyValue: => A) extends Function0[A] {
    private var func: () => Any = () => lazyValue
    private var value: Any = null

    override def apply() = {
      if (func != null) {
        value = func().asInstanceOf[A]
        func = null
      }
      value.asInstanceOf[A]
    }

    override def toString() =
      if (func == null) "Susp(" + value + ")"
      else "Susp(?)"
  }

  def delay[A](value: => A) = new Susp[A](value)
  implicit def force[A](s: Susp[A]): A = s()
}

object Test {
  import forceDelay._
  
  def main(args: Array[String]) = {
    val s: Susp[Int] = delay { Console.println("evaluating..."); 3 }
    Console.println("s = " + s)
    Console.println("s() = " + s())
    Console.println("s = " + s)
    Console.println("2 + s = " + (2 + s))
  }
}