Components — KMP

The decompose module provides the building blocks for KMP presentation logic.

BaseComponent

BaseComponent<VS : Any, E : Any> is the main base class for components.

Constructor parameters:

• componentContext: GenericComponentContext<*> — Decompose component context
• defaultState: VS — initial state value

Key members:

• componentState: MutableStateFlow<VS> — protected mutable state
• componentCoroutineScope — a MainScope() tied to the component lifecycle (cancelled on destroy)
• events: Flow<E> — flow of one-shot UI events backed by a Channel
• sendUiEvent(event: E) — protected function to emit an event
• fun Flow<VS>.asStateFlow(started): StateFlow<VS> — protected helper to convert a Flow to a StateFlow within the component scope

Complete Example

class HomeComponent(
    componentContext: AppComponentContext,
    private val observeUserUseCase: ObserveUserUseCase,
    private val navigation: HomeNavigation,
) : BaseComponent<HomeState, HomeUiEvent>(componentContext, HomeState()),
    CoroutineScopeOwner {

    override val coroutineScope = componentCoroutineScope

    val state: StateFlow<HomeState> = componentState

    init {
        observeUserUseCase.execute(Unit) {
            onNext { componentState.value = componentState.value.copy(userName = it.name) }
            onError { sendUiEvent(HomeUiEvent.ShowError(it.message.orEmpty())) }
        }
    }

    fun onDetailClick() {
        navigation.toDetail()
    }
}

Note

BaseComponent does not implement CoroutineScopeOwner directly. To execute use cases, implement CoroutineScopeOwner in your component and set coroutineScope to componentCoroutineScope.

Supporting Types

• ArkitektComponentContext<T> — interface extending GenericComponentContext<T>. Use it as the base for your app's component context type.
• UiEvent — marker interface for one-shot events.

Koin Factory Generation

Use the @GenerateFactory annotation to generate Koin factory functions for your components. See the Factory Generator section for details.