Kotlin InterfaceDelegation

snippet.kt

interface View {
  fun click()
  fun toggle()
}

class ViewImpl: View {
  override fun click()  { println("click!") }
  override fun toggle() { println("toggle!") }
}

class EmptyDelegate(view: View): View by view

class OverridingDelegate(view: View): View by view {
  override fun click()  { println("CLICK!") }
}

fun main() {
  val v = ViewImpl()
  EmptyDelegate(v).click()
  OverridingDelegate(v).click()
}