Drew example

gistfile1.scala

import scala.collection.Map
import scala.sys.error
import java.util.TimeZone
import scala.reflect.Manifest

class FieldMapping[V, P: Manifest](val code: Int, val toPrimitive: V => P, val fromPrimitive: P => V) {
  type PrimitiveMap = Map[Int, Any]
  
  def this(code: Int) = this(code, _.asInstanceOf[P], _.asInstanceOf[V])

  def get(map: PrimitiveMap): Option[V] = map.get(code) match {
    case Some(p: P) => Some(fromPrimitive(p))
    case Some(x) => error("Expected primitive of type " + manifest[P] + " but found " + x.getClass + " for code " + code)
    case None => None
  }
  
  def put(map: PrimitiveMap, value: Option[V]): PrimitiveMap = {
    val newPair = value.map(v => code -> toPrimitive(v))
    map ++ newPair
  }
}

object FieldMapping extends App {
  val timeZone = TimeZone.getTimeZone("UTC")
  val field = new FieldMapping[TimeZone, String](11, _.getID, id => TimeZone.getTimeZone(id))
  val primitive = field.toPrimitive(timeZone)
  val value = field.fromPrimitive(primitive)
  
  println(primitive.getClass + " : " + primitive)
  println(value.getClass + " : " + value)

  val emptyMap = Map.empty[Int, Any]
  val map = field.put(emptyMap, Some(timeZone))
  println(map)
  println(field get map)
}