polson

class BetterDialog<T> : DialogFragment() {
    companion object {
        val KEY_ARGS = "KEY_ARGS"
        val KEY_CALLED_FROM_FRAGMENT = "KEY_CALLED_FROM_FRAGMENT"
        val TAG = "DIALOG_TAG"
    }

    @Suppress("UNCHECKED_CAST")
    private val args: DialogBuilderImpl.DialogArgs<T> by lazy {
        checkNotNull(arguments?.getSerializable(KEY_ARGS) as DialogBuilderImpl.DialogArgs<T>) { "Args are null!" }

polson

private class DialogBuilderImpl<T>(val context: Context) : DialogBuilder<T> {

    data class DialogArgs<T>(
        val title: String? = null,
        val message: String? = null,
        val yesButtonAction: Serializable? = null,
        val noButtonAction: Serializable? = null,
        val yesButtonText: String? = null,
        val noButtonText: String? = null
    ) : Serializable

polson

private typealias DialogCallback<T> = T.() -> Unit

interface DialogBuilder<T> {
    fun title(title: String)

    fun title(titleResId: Int)

    fun message(message: String)

    fun message(messageResId: Int)

polson

class BetterActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val button = findViewById<Button>(R.id.button)
        button.setOnClickListener { showBetterDialog() }

        val normalButton = findViewById<Button>(R.id.normalButton)
        normalButton.setOnClickListener { launchNormalActivity() }

polson

class NormalActivity : AppCompatActivity(), NormalDialogFragment.NormalDialogListener {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_normal)

        val button = findViewById<Button>(R.id.normalButton)
        button.setOnClickListener { showNormalDialog() }
    }

    private fun showNormalDialog() =

polson

/**
 * Provides a single instance of a class requiring a context.  Can be inherited by a companion
 * object to easily make it a singleton
 */
abstract class SingletonWithContext<T> {
    @Volatile
    private var instance: T? = null

    fun getInstance(context: Context): T =
            instance ?: synchronized(this) {

polson

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"

polson

private fun scanForActivity(context: Context?): FragmentActivity? = when (context) {
    is FragmentActivity -> context
    is ContextWrapper -> scanForActivity(context.baseContext)
    else -> throw IllegalArgumentException("Context must be a FragmentActivity!")
}

polson

    @Suppress("UNCHECKED_CAST")
    private inline fun <reified T : ViewModel> createViewModel(key: String, crossinline initializer: () -> T): T {
        val factory = object : ViewModelProvider.NewInstanceFactory() {
            override fun <T : ViewModel?> create(modelClass: Class<T>): T = initializer() as T
        }
        return ViewModelProviders.of(activity, factory).get(key, T::class.java)
    }

polson

class MyView(context: Context) : FrameLayout(context) {
    private val viewModel by lazy { setupViewModel() }
    private val activity by lazy { scanForActivity(context) }

    private fun scanForActivity(context: Context?): FragmentActivity = when (context) {
        is FragmentActivity -> context
        is ContextWrapper -> scanForActivity(context.baseContext)
        else -> throw IllegalArgumentException("Context must be a FragmentActivity!")
    }