kotlins_simple_layout_trick_pt2_view_extensions.kt

BindableLayout.kt

open class BindableLayout<T, V : ViewGroup>(
        layout: V,
        private val observable: Observable<T>
) : Layout<V>(layout) {

    init {
        layout.addOnAttachStateChangeListener(DisposableOnAttachStateChangeListener {
            observable.subscribe(observers)
        })
    }

    // ...
}

class DisposableOnAttachStateChangeListener(
        private val onViewAttachedToWindow: (view: View) -> Disposable
) : View.OnAttachStateChangeListener {

    private var disposable: Disposable? = null

    override fun onViewAttachedToWindow(view: View) {
        disposable = onViewAttachedToWindow.invoke(view)
    }

    override fun onViewDetachedFromWindow(view: View) {
        disposable?.dispose()
    }

}