scala> object O {
     |   def unapply(s: String) = Some(1)
     | }
defined object O
scala> 1 match {
     |   case O(n) => n
     |   case _ => -42
     | }
res2: Int = -42

scala> 1 match {
     |   case pattern(_) => 0
     |   case _       => -42
     | }
warning: there was one deprecation warning; re-run with -deprecation for details
res1: Int = -42