Access to companion object via implicit resolution

gistfile1.scala

// See this mailing list thread for context:
//   https://groups.google.com/d/topic/scala-language/ImqJuGylyi8/discussion

case class Companion[-C, T](t : T)

trait Publish[C, T] { self : T =>
  implicit val companion = Companion[C, T](this)
}

trait StaticKey {
  def key : String
}

object A extends StaticKey with Publish[A, StaticKey] {
  val key = "KeyA"
}

object B extends StaticKey with Publish[B, StaticKey] {
  val key = "KeyB"
}

trait Item {
  // Resolve reference to companion implicitly ... note use of this.type
  def key(implicit c : Companion[this.type, StaticKey]) = c.t.key
}

class A extends Item

class B extends Item

object TestKey extends App {
  val a = new A
  assert(a.key eq A.key)
  
  val b = new B
  assert(b.key eq B.key)
}