Pattern Matching with Private Field - scala

Question

Given:
scala> case class ParentPath(private val x: String) {
| val value = x.dropWhile(_ == '/')
| }
I can make a ParentPath:
scala> ParentPath("/foo")
res10: ParentPath = ParentPath(/foo)
I can't access its x (due to private, it appears).
scala> res10.
asInstanceOf canEqual copy isInstanceOf productArity productElement productIterator productPrefix toString value
I can get its value.
scala> res10.value
res11: String = foo
However, I'd prefer to return its value rather than x upon a pattern match:
scala> res10 match { case ParentPath(x) => x}
res13: String = /foo
How can I pattern match with value rather than x?
scala> ParentPath.unapply(res10)
res15: Option[String] = Some(/foo)
I tried to override ParentPath#unapply, but got a compile-time error:
scala> case class ParentPath(private val x: String) {
| val value = "foo"
| override def unapply(p: ParentPath): Option[String] = Some(value)
| }
<console>:15: error: method unapply overrides nothing
override def unapply(p: ParentPath): Option[String] = Some(value)
^

Answer 1

The unapply method belongs in the companion object, and you cannot override it for a case class, anyway. For a normal class, this will work. Or, if you simply use a differently named object that has an unapply method of the same signature.
class ParentPath(private val x: String) {
val value = "foo"
}
object ParentPath {
def unapply(p: ParentPath): Option[String] = Some(p.value)
}
scala> new ParentPath("/foo") match { case ParentPath(x) => x }
res1: String = foo