timeThis implementation

gistfile1.scala

trait TimeUnit
case object msecs extends TimeUnit
case object nanosecs extends TimeUnit
object Watch{
  /* A hashmap to map a time unit to a tuple containing:
  * - a description of the time unit in english.
  * - a function invoked to measure the time in the given unit
  */
  val timeUnits = Map[TimeUnit,Tuple2[String,() => Long]] (
    msecs -> ("msecs",System.currentTimeMillis _),
    nanosecs -> ("nanosecs", System.nanoTime _)
  ) 
  
  /*
   * Execute a block of code and displays how long its execution took.
   * The time unit can be set to msecs or nanoseconds by providing the appropriate time unit object as a parameter.
  */
  def timeThis(tu : TimeUnit)(block: => Unit){
    timeUnits.get(tu) match{
     case Some((description,fn)) =>{
      // Measure the start time using the appropriate function.
      var start = fn()

      // Execute the block
      block

      // Measure the stop time using the appropriate function.
      var stop  = fn()
      
      println ("It took " + (stop - start) + " " + description + " to execute the operation.")
      }
      case _ => println ("Unknown time unit " + tu)
    }
  }
  
  def timeThis( block: => Unit){
    timeThis(msecs)(block)
  }
}
// Scala import to be able to use methods defined in Watch object.
import Watch._