trait MaxLenValidation {
  val maxLen:Int
  msg :String
  override def validations =
    valMaxLen( maxLen,msg )_ :: super.validations
}

class Memo extends LongKeyedMapper[Message] with IdPK {
  def getSingleton = Message

  object contents extends MappedString(this, 140)
    with MaxLenValidation{
    val maxLen = 140
    val msg:String = "Too Long!"
  }
}