Android bind view extension function

ActivityExt.kt

fun <T : View> Activity.bindView(viewId: Int) =
    lazy { this.findViewById<T>(viewId) }

MainActivity.kt

/**
* Thanks to the lazy delegate, finding the view by id will be postponed until the property is used for the first time.
* This has some important optimisation improvements over the standard `lateinit` pattern usually used:
* 1. Property is read only
* 2. Initialization and definition can be kept together
* 3. Unused properties will be marked by IDE.
* 4. View reference that is never used will never be associated with the view element, and `findViewById` can be expensive.

* Excerpt From
* [Early Access] Advanced Kotlin
* Marcin Moskała
*/

class MainActivity : Activity() {

    var questionLabelView: TextView by
    bindView(R.id.main_question_label)
    var answerLabelView: TextView by
    bindView(R.id.main_answer_label)
    var confirmButtonView: Button by
    bindView(R.id.main_button_confirm)

    override fun onCreate(savedInstanceState: Bundle) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.main_activity)
    }
}