How to workaround Class and Companion object in REPL

As you can see below the companion object can't access the private variable from the Class Person. This is due to a different scope. To fix it you will need to define a container (can be called something else by the way).

scala> class Person {
     | private var firstname = "Robby"
     | private var lastname = "Pelssers"
     | }
defined class Person

scala> object Person {
     | def getFirstName(p: Person) = p.firstname
     | }
:9: error: variable firstname in class Person cannot be accessed in Person
       def getFirstName(p: Person) = p.firstname

scala> object container {
     |   class Person {
     |      private var firstname = "Robby"
     |      private var lastname = "Pelssers"
     |   }
     |
     |   object Person {
     |       def getFirstName(p: Person) = p.firstname
     |   }
     | }
defined module container

scala> import container.Person
import container.Person

scala> val person = new Person()
person: container.Person = container$Person@1a71d29a

scala> Person.getFirstName(person)
res0: java.lang.String = Robby

Important side note!! As of Scala 2.9.x you can use the :paste command and everything will work normally.

scala> :paste
// Entering paste mode (ctrl-D to finish)

class Person {
  private var firstname = "Robby"
  private var lastname = "Pelssers"
}

object Person {
  def getFirstName(p: Person) = p.firstname
}

// Exiting paste mode, now interpreting.

defined class Person
defined module Person

scala> Person.getFirstName(new Person())
res0: java.lang.String = Robby