Scala Multiple Nested Case Clases

Question

Good day everyone, I create the following case class on SCALA:

sealed abstract class Value;
  case class U(name: String) extends Value
  case class L(name: String) extends Value
  case class B(name: String) extends Value

  sealed abstract class Term
  case class Var(name: String) extends Term //variable name
  case class Val(value: Value) extends Term //value

sealed abstract class Pattern //patterns
  case class BGP(subject: Term, predicate: Term, obj: Term) extends Pattern
  case class And( pat1: Pattern, pat2: Pattern) extends Pattern
  case class Filter(pred: Predicate, pattern: Pattern ) extends Pattern


def function(p: Pattern): Unit = p match { 
    case BGP(Var(x), Val(y), Val(z)) => {
      val con:conv = new conv()
      val valor:Value = Val(y).value
}

Then, as you can see, BGP contains Term and extends to pattern, Val contains Values and extends to Term, and U,L,B contains Strings and extends to Value, In my function I want to access to the strings that contains the U or L or B case classes, the variable valor = Val(y).value contains a U class for example, but when I write valor.XXXX don't appear me the name option. The big question is How can I do to accesss to the String name from U?

You treat your U, L, B class instance as a Value, which doesn't have any methods/fields declared but you expect it to magically have them when you want? :D — insan-e
– insan-e, Commented Apr 27, 2017 at 9:39
Yes, I expect the magic properties from SCALA, XD, @flavian gave me the correct answer — Vladimir Rincon
– Vladimir Rincon, Commented Apr 27, 2017 at 16:18

flavian · Accepted Answer · 2017-04-26 23:49:26Z

2

You just define it on Value which btw could be a trait.

sealed trait Value {
  def name: String
}
case class U(name: String) extends Value
case class L(name: String) extends Value
case class B(name: String) extends Value

answered Apr 26, 2017 at 23:49

flavian

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3 Comments

Vladimir Rincon Over a year ago

This classes in this moment are under a trait: trait SPARQLInterpreter { sealed abstract class Value; case class URI(name: Node) extends Value case class Literal(name: Node) extends Value case class BlankNode(name: Node) extends Value

flavian Over a year ago

@VladimirRincon I don't see how that makes a difference, can you not access the Value class, is that what you are saying?

Vladimir Rincon Over a year ago

Ok @flavian, I see your point and I implemented, you are right and it works, thank you!!

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