Get companion object of class by given generic type Scala

Question

What I am trying to do is to make a function that would take a generic class and use a static method in it (sorry for Java language, I mean method of its companion object).<

Answer 1

You could use reflection to get the companion class and its instance, but that relies on Scala internals that might change in some far(?) future. And there is no type safety as you get an AnyRef. But there is no need to add any implicits to your classes and objects.

def companionOf[T : Manifest] : Option[AnyRef] = try{
  val classOfT = implicitly[Manifest[T]].erasure
  val companionClassName = classOfT.getName + "$"
  val companionClass = Class.forName(companionClassName)
  val moduleField = companionClass.getField("MODULE$")
  Some(moduleField.get(null))
} catch {
  case e => None
}

case class A(i : Int)

companionOf[A].collect{case a : A.type  => a(1)}
// res1: Option[A] = Some(A(1))