Question

I’m currently learning Scala and I have some problems designing my case classes. I need two case classes that have the same properties. So I thought I would be a good idea to inherit from an abstract base class that defines these properties. However this code does not compile

abstract class Resource(val uri : String)

case class File(uri : String) extends Resource(uri)
case class Folder(uri : String) extends Resource(uri)

because uri in the case class constructors would overwrite the uri property of the base class.

What would be the correct way to design this?

I want to be able to do something like this

val arr = Array[Resource](File("test"), Folder("test2"))

arr.foreach { r : Resource => r match {
  case f : File => println("It's a file")
  case f : Folder => println("It's a folder")
} }

The “equivalent” Java code should be something like

abstract class Resource {
   private String uri;

   public Resource(String uri) {
       this.uri = uri
   }

   public String getUri() {
       return uri;
   }
}

// same for Folder
class File extends Resource {
    public File(String uri) {
        super(uri);
    }
}

Answer 1

The correct syntax should be:

abstract class Resource {
   val uri: String
}

case class File(uri : String) extends Resource
case class Folder(uri : String) extends Resource


Stream[Resource](File("test"), Folder("test2")) foreach { 
  r : Resource => r match {
   case f : File => println("It's a file")
   case f : Folder => println("It's a folder")
} }

---

EDIT

Without case classes:

abstract class Resource(val uri : String)

class File(uri : String) extends Resource(uri) {
   override def toString = "..."
}
object File {
   def apply(uri: String) = new File(uri)
}

class Folder(uri : String) extends Resource(uri) {
   override def toString = "..."
}
object Folder {
   def apply(uri: String) = new Folder(uri)
}