adam-arold

object Positions {

   @JvmStatic
   @JvmOverloads
   fun create(x: Int,
              y: Int = x) = Position.create(x, y)
}

adam-arold

interface Position {

   val x: Int
   val y: Int

   fun calculateArea(): Int = x.times(y)

   companion object {

       @JvmOverloads

adam-arold

open class PositionBase(
       override val x: Int,
       override val y: Int) : Position {

   final override fun calculateArea(): Int {
       return super.calculateArea()
   }
}

adam-arold

abstract class PositionBase : Position

adam-arold

interface Position {
  
   val x: Int
   val y: Int
  
   fun calculateArea(): Int = x.times(y)
}

adam-arold

class EventBus {

   @JvmName("subscribe") 
   internal fun <T: Event> subscribe(eventType: Class<T>) {
      
   }

}

adam-arold

// reified is not visible from Java
class EventBus {

   inline fun <reified T : Event> subscribe(
           noinline callback: (T) -> Unit) {
       // ...
   }

}

adam-arold

interface Position {

   val x: Int
   val y: Int

}

// idiomatic in Kotlin
pos.x
pos.y

adam-arold

fun usage() {
   EventBus().subscribe<Event> {  }
}

adam-arold

inline fun <reified T : Event> EventBus.subscribe(
      noinline callback: (T) -> Unit) {
   return subscribe(
           klass = T::class,
           callback = callback)
}