package foo import kotlin.reflect.KProperty class Delegate { var inner = 1 inline operator fun getValue(t: Any?, p: KProperty<*>): Int = inner inline operator fun setValue(t: Any?, p: KProperty<*>, i: Int) { inner = i } } fun box(): String { var prop: Int by Delegate() if (prop != 1) return "fail get" prop = 2 if (prop != 2) return "fail set" return "OK" }