Add suspend room db accessor

[LouisCAD]

No description provided.

[LouisCAD]

Example of home grown technique:

private val someDb by lazy { roomDb<SomethingDatabase>("something") }
suspend fun someDb() = withContext(ioDispatcher) { someDb }

With such a function:

suspend operator fun <T : RoomDatabase> Lazy<T>.invoke(): T = if (isInitialized()) value
else withContext(ioDispatcher) { value }

this can be reduced to this:

val someDb = lazy { roomDb<SomethingDatabase>("some") } // Client code

[LouisCAD]

The suspend operator fun invoke should be put in a sub-package named lazydb so it looks obvious from the imports

[LouisCAD]

Here's an implementation of this issue in the sample sources:

Splitties/sample/src/main/java/com/louiscad/splittiessample/extensions/coroutines/SuspendLazyRoom.kt

Lines 9 to 19 in 8510b5a

	inline fun <reified DB : RoomDatabase> roomDataBase(
	name: String,
	crossinline config: DbConfig<DB> = {}
	): LazyRoom<DB> =
	LazyRoom(lazy { roomDb(name, config) })
	class LazyRoom<T : RoomDatabase> @PublishedApi internal constructor(private val lazyDb: Lazy<T>) {
	suspend operator fun invoke(): T = with(lazyDb) {
	if (isInitialized()) value else withContext(Dispatchers.IO) { value }
	}
	}

[LouisCAD]

The SuspenLazy class allows more than just usage for Room:

Splitties/sample/src/main/java/com/louiscad/splittiessample/extensions/coroutines/SuspendLazy.kt

Lines 7 to 15 in 4b444d0

	open class SuspendLazy<out T>(
	private val dispatcher: CoroutineDispatcher = Dispatchers.Default,
	initializer: () -> T
	) {
	private val lazyValue = lazy(initializer)
	suspend operator fun invoke(): T = with(lazyValue) {
	if (isInitialized()) value else withContext(dispatcher) { value }
	}
	}

Here's how it can be used for Room:

Splitties/sample/src/main/java/com/louiscad/splittiessample/extensions/coroutines/SuspendLazyRoom.kt

Lines 8 to 11 in 4b444d0

	inline fun <reified DB : RoomDatabase> roomDataBase(
	name: String,
	crossinline config: DbConfig<DB> = {}
	): SuspendLazy<DB> = SuspendLazy(Dispatchers.IO) { roomDb(name, config) }

it can also be used for SharedPreferences:

Splitties/sample/src/main/java/com/louiscad/splittiessample/prefs/GamePreferences.kt

Lines 23 to 24 in 4b444d0

	class GamePreferences private constructor() : Preferences("gameState") {
	companion object : SuspendLazy<GamePreferences>(Dispatchers.IO, ::GamePreferences)