June 2018 Update

Task/Delegates/Kotlin/delegates.kotlin

@@ -0,0 +1,25 @@
+// version 1.1.51
+
+interface Thingable {
+    fun thing(): String?
+}
+
+class Delegate(val responds: Boolean) : Thingable {
+    override fun thing() = if (responds) "delegate implementation" else null
+}
+
+class Delegator(d: Delegate) : Thingable by d {
+    fun operation() = thing() ?: "default implementation"
+}
+
+fun main(args: Array<String>) {
+    // delegate doesn't respond to 'thing'
+    val d = Delegate(false)
+    val dd = Delegator(d)
+    println(dd.operation())
+
+    // delegate responds to 'thing'
+    val d2 = Delegate(true)
+    val dd2 = Delegator(d2)
+    println(dd2.operation())
+}