Presenter abstract for MVP architecture

Presenter.kt

abstract class Presenter<V> : CoroutineScope {
    protected var TAG: String = javaClass.simpleName
    private var view: WeakReference<V>? by Delegates.observable<WeakReference<V>?>(null) { _, _, _ ->
        this.onViewChanged()
    }

    protected var job = Job()
    override val coroutineContext: CoroutineContext
        get() {
            if (job.isCancelled || job.isCompleted) {
                job = Job()
            }
            return job + Dispatchers.Main
        }

    protected open fun onBind() {
        job.cancel()
    }
    protected open fun onUnbind() {}
    protected open fun onViewChanged() {}

    fun takeView(view: V) {
        if (this.view?.get() !== view) {
            this.view?.clear()
            this.view = WeakReference(view)
        }

        this.onBind()
    }

    fun dropView(view: V) {
        this.onUnbind()
        job.cancel()

        if (this.view?.get() === view) {
            this.view = null
        }
    }

    protected fun view(): V? {
        if (view == null) {
            Log.w("Presenter", "View is null for $TAG")
            return null
        } else {
            return view?.get()
        }
    }

    protected fun hasView(): Boolean {
        return view() != null
    }
}