Kotlin property delegates for SharedPreferences

Examples.kt

val preferences : SharedPreferences = ...

//Old way...
val MY_BOOLEAN_PREF = "myBooleanPref"
val MY_STRING_PREF = "myStringPref"

fun oldSharedPreferenceExample() {
    //set
    val editor = preferences.edit()
    editor.putBoolean(MY_BOOLEAN_PREF, true)
    editor.putString(MY_STRING_PREF, "this is some text")
    editor.apply()

    //get
    val bool = preferences.getBoolean(MY_BOOLEAN_PREF, false)
    val text = preferences.getString(MY_STRING_PREF, "")
}

//New way...
var SharedPreferences.myBooleanPref by Pref(false)
var SharedPreferences.myStringPref by Pref("")

fun newSharedPreferenceExample() {
    //set
    preferences.myBooleanPref = true
    preferences.myStringPref = "this is some text"

    //get
    val bool = preferences.myBooleanPref
    val text = preferences.myStringPref
}

Prefs.kt

import android.content.SharedPreferences
import kotlin.reflect.KProperty

class Pref<T>(val default : T) {

    operator fun getValue(prefs: SharedPreferences, property: KProperty<*>): T = with(prefs) {
        val name = property.name

        @Suppress("UNCHECKED_CAST")
        val value: Any = when (default) {
            is Long -> getLong(name, default)
            is String -> getString(name, default)
            is Int -> getInt(name, default)
            is Boolean -> getBoolean(name, default)
            is Float -> getFloat(name, default)
            is Set<*> -> getStringSet(name, default as Set<String>)
            else -> throw IllegalArgumentException("$default is not a valid Pref type")
        }

        @Suppress("UNCHECKED_CAST")
        return value as T
    }

    operator fun setValue(prefs: SharedPreferences, property: KProperty<*>, value: T) = with(prefs.edit()) {
        val name = property.name

        @Suppress("UNCHECKED_CAST")
        when (value) {
            is Long -> putLong(name, value)
            is String -> putString(name, value)
            is Int -> putInt(name, value)
            is Boolean -> putBoolean(name, value)
            is Float -> putFloat(name, value)
            is Set<*> -> putStringSet(name, value as Set<String>)
            else -> throw IllegalArgumentException("$value is not a valid Pref type")
        }.apply()
    }
}