Functional Kotlin

Extension functions as members

Extension functions can be declared as members of a class. An instance of a class with extension functions declared is called the dispatch receiver.

The Caregiver open class internally defines, extension functions for two different classes, Feline and Primate:

open class Caregiver(val name: String) {   open fun Feline.react() = "PURRR!!!"      fun Primate.react() = "*$name plays with ${[e-mail]}*"   fun takeCare(feline: Feline) {      println("Feline reacts: ${feline.react()}")   }      fun takeCare(primate: Primate){      println("Primate reacts: ${primate.react()}")   }}

Both extension functions are meant to be used inside an instance of Caregiver. Indeed, it is a good practice to mark member extension functions as private, ...