nextersolutions

fun processPayment(
    order: Order,
    analytics: AnalyticsContext  // the uninvited guest at every layer
) {
    analytics.track("payment_started", order.id)
}

nextersolutions

data class AnalyticsContext(
    val sessionId: String,
    val experimentVariant: String,
) {
    fun track(event: String, payload: Any) { /* ... */ }
}

context(analytics: AnalyticsContext)
fun processPayment(order: Order) {
    analytics.track("payment_started", order.id)

nextersolutions

interface Logger {
    fun log(message: String)
}

context(logger: Logger)
fun fetchUserData(userId: String): User {
    logger.log("Fetching user: $userId")
    // actual fetch logic
    return User(userId)
}

nextersolutions

data class MyState(val counter: Int = 0)

class MyViewModel : ViewModel() {

    private val _state = MutableStateFlow(MyState())

    val state: StateFlow<MyState> = with(viewModelScope) {
        _state
            .onStart { /* warm-up logic */ }
            .stateInWhileSubscribed(initialValue = MyState())

nextersolutions

context(scope: CoroutineScope)
fun <T> Flow<T>.stateInWhileSubscribed(initialValue: T): StateFlow<T> =
    stateIn(
        scope,
        SharingStarted.WhileSubscribed(stopTimeoutMillis = 5_000L),
        initialValue
    )

nextersolutions

fun <T> ViewModel.stateInWhileSubscribed(
    initialValue: T
): StateFlow<T> = stateIn(
    viewModelScope,
    SharingStarted.WhileSubscribed(stopTimeoutMillis = 5_000L),
    initialValue
)