By Name Parameter

byname.scala

/*
  a by name parameter is not evaluated at the point of function application
  but rather it is evaluated at each use within the function
*/
object App {
  def main (args: Array[String]){
    println(delayed(nano()))
  }
  
  def nano() ={
    println("Getting Nano")
    System.nanoTime
  }

  def delayed(t: => Long) = { // indicates by-name parameter
    println("In Delayed Method")
    println("Param: " + t)    //evaluates t
    t                         //Evaluates t again
                              //This results in Getting Nano being printed
                              //twice
  }
}