Praktiska reified-mönster: parsning, DI och serialisering

inline fun <reified T> String.parseList(): List<T> {
    val type = object : TypeToken<List<T>>() {}.type
    return Gson().fromJson(this, type)
}

val users: List<User> = jsonString.parseList()

val user = Json.decodeFromString<User>(jsonString)
// equivalent to: Json.decodeFromString(serializer<User>(), jsonString)

object ServiceLocator {
    val registry = mutableMapOf<KClass<*>, Any>()
    inline fun <reified T : Any> get(): T =
        registry[T::class] as? T ?: error("No binding for ${T::class}")
    inline fun <reified T : Any> bind(instance: T) {
        registry[T::class] = instance
    }
}

inline fun <reified VM : ViewModel> ComponentActivity.viewModel(): VM =
    ViewModelProvider(this)[VM::class.java]

// Usage
val vm: MyViewModel by lazy { viewModel() }

inline fun <reified T> Any?.safeCast(): T? = this as? T

val name: String? = someAny.safeCast<String>()

inline fun <reified T> List<Any>.onlyInstancesOf(block: (T) -> Unit) =
    filterIsInstance<T>().forEach(block)

items.onlyInstancesOf<Button> { it.setEnabled(true) }

class EventBus {
    val handlers = mutableMapOf<KClass<*>, (Any) -> Unit>()
    inline fun <reified E : Any> on(noinline handler: (E) -> Unit) {
        handlers[E::class] = { handler(it as E) }
    }
    fun post(event: Any) = handlers[event::class]?.invoke(event)
}

inline fun <reified T : Any> SharedPreferences.get(key: String, default: T): T = when (T::class) {
    Int::class    -> getInt(key, default as Int) as T
    String::class -> getString(key, default as String) as T
    Boolean::class -> getBoolean(key, default as Boolean) as T
    else -> error("Unsupported type ${T::class}")
}

val result: List<String> = """["a","b","c"]""".parseList<String>()
assertEquals(listOf("a","b","c"), result)