fun Any.getDelegate<T>(prop: KProperty<T>): Any {
    return javaClass.getDeclaredField("${prop.name}$delegate").let {
        it.setAccessible(true)
        it.get(this)
    }
}

val delegate = a.getDelegate(A::b)

val delegate = a.b.delegate

fun Any.addObservable<T>(prop: KProperty<T>, observer: (T) -> Unit) {
    getObservableProperty(prop).observers.add(observer)
}

fun Any.getObservableProperty<T>(prop: KProperty<T>): ObservableProperty<T> {
    return getDelegate(prop) as ObservableProperty<T>
}

fun Any.getDelegate<T>(prop: KProperty<T>): Any {
    return javaClass.getDeclaredField("${prop.name}$delegate").let {
        it.setAccessible(true)
        it.get(this)
    }
}

class ObservableProperty<T>(
        initialValue: T,
        initialObservers: Array<(T) -> Unit> = emptyArray()) : ReadWriteProperty<Any?, T> {

    private var value = initialValue

    public val observers: MutableSet<(T) -> Unit> = initialObservers.toHashSet()

    public override fun get(thisRef: Any?, desc: PropertyMetadata): T {
        return value
    }

    public override fun set(thisRef: Any?, desc: PropertyMetadata, value: T) {
        this.value = value
        observers.forEach { it(value) }
    }
}

class A() {
    var b by ObservableProperty(0)
}

fun main(args: Array<String>) {
    val a = A()

    a.addObservable(A::b) {
        println("b is now $it")
    }

    a.b = 1
    a.b = 2
    a.b = 3
}

class A() {
    var foo by ObservableProperty(0)
}

class B() {
    var foo by ObservableProperty(0)
}

fun main(args: Array<String>) {
    val a = A()

    a.addObservable(B::foo) {
        println("b is now $it")
    }

    a.foo = 1
    a.foo = 2
    a.foo = 3
}

class Stuff(val thing: String)

val stuff = Stuff("cool stuff")
val thingFieldName = "${stuff.thing}$delegate"
// value of thingFieldName is now "thing"