Scala extractor with "collect" example

gistfile1.txt

object MemberType extends Enumeration {
  type MemberType = Value
  val Free, Trial, Pay, Premium = Value
}

object MemberStatus extends Enumeration {
  type MemberStatus = Value
  val Active, Inactive, Disabled = Value
}
    
class DataRecord(val id: Long, val status: MemberStatus.Value, val name: String, val memType: MemberType.Value, val accessKey: String) 
//.. envision DataRecord actually having 30+ attributes

trait Member {
  val name: String
}

class Free(val name: String) extends Member
object Free {
  def unapply(d: DataRecord): Option[Member] = {
    if(d.memType == MemberType.Free)
      Option(new Free(d.name))
    else
      None
  }
}

class Pay(val name: String) extends Member
object Pay {
  def unapply(d: DataRecord): Option[Member] = {
    if(d.status == MemberStatus.Active && d.memType == MemberType.Trial || d.memType == MemberType.Pay) 
      Option(new Pay(d.name))
    else 
      None 
    }
}

class Premium(val name: String, val accessKey:  Option[String]) extends Member
object Premium {
  def unapply(d: DataRecord): Option[Member] = {
    if(d.status == MemberStatus.Active && d.memType == MemberType.Premium)
      Option(new Premium(d.name, Option(d.accessKey)))
    else
      None
  }
}


val pierre = new DataRecord(1, MemberStatus.Inactive, "Pierre", MemberType.Pay, "1111")
val joanne = new DataRecord(2, MemberStatus.Inactive, "Joannne", MemberType.Free, "")
val du = new DataRecord(3, MemberStatus.Active, "Du", MemberType.Premium, "3333")
val petra = new DataRecord(4, MemberStatus.Disabled, "Petra", MemberType.Premium, "4444")
val chin = new DataRecord(5, MemberStatus.Active, "Chin", MemberType.Trial, "5555")
val carlos = new DataRecord(6, MemberStatus.Active, "Carlos", MemberType.Pay, "6666")
val tran = new DataRecord(7, MemberStatus.Active, "Tran", MemberType.Pay, "7777")
val alva = new DataRecord(8, MemberStatus.Active, "Alva", MemberType.Premium, "8888")
val nan = new DataRecord(9, MemberStatus.Active, "Nan", MemberType.Free, "")
val steve = new DataRecord(10, MemberStatus.Active, "Steve", MemberType.Free, "101010")

val allData = List(pierre, joanne, du, petra, chin, carlos, tran, alva, nan, steve)

def getMembers(allData: List[DataRecord], whichType: { def unapply(d: DataRecord): Option[Member] }): List[Member] = allData collect { case whichType(n) => n }

def premiumMembers = getMembers(allData, Premium)
def payMembers = getMembers(allData, Pay)

def greetMembers(memList: List[Member], greeting: String) = for(m <- memList) { println(String.format(greeting, m.name)) }
def premiumGreeting = "Hello, %s! Premium members get the best experience! "
def payGreeting = "Hello, %s! Become a premium member and upgrade your experience!"

greetMembers(premiumMembers, premiumGreeting)
greetMembers(payMembers, payGreeting)


//An alternative to the above approach is to pass the class to the method
def makeMember(allData:List[DataRecord], typeOfMemberToMake: Class[_]) = {
    //You must create stable identifiers to match on class
    //See http://stackoverflow.com/questions/7157143/how-can-i-match-classes-in-a-scala-match-statement
    val ClassFree = classOf[Free]
    val ClassPay = classOf[Pay]
    val ClassPremium = classOf[Premium]
    typeOfMemberToMake match {
        case ClassFree => { allData collect { case Free(n) => n } }
        case ClassPay => { allData collect { case Pay(n) => n } }
        case ClassPremium => { allData collect { case Premium(n) => n } }
     }
}