ChildPresenter

Marks a presenter class as a child presenter exposed through a graph extension scoped to its parent host (typically a tab pager presenter).

Without this annotation a parent presenter that exposes child presenters has to hand-write the @GraphExtension interface with each child as a property, plus the nested factory contributing to the parent's scope. With this annotation the processor emits one @GraphExtension for each annotated child, named <Presenter>ChildGraph, that the parent presenter can consume as a factory.

Example

@Inject
@ChildPresenter(
    scope = ProgressChildScope::class,
    parentScope = ProgressRoot::class,
)
public class UpNextPresenter(
    componentContext: ComponentContext,
    // ... deps
) : ComponentContext by componentContext

The processor emits one file (UpNextChildGraph.kt) into the presenter's <package>.di sub-package:

@GraphExtension(ProgressChildScope::class)
public interface UpNextChildGraph {
    public val upNextPresenter: UpNextPresenter

    @ContributesTo(ProgressRoot::class)
    @GraphExtension.Factory
    public interface Factory {
        public fun createUpNextGraph(@Provides componentContext: ComponentContext): UpNextChildGraph
    }
}

The parent presenter consumes one factory for each child:

@Inject
public class ProgressPresenter(
    componentContext: ComponentContext,
    upNextGraphFactory: UpNextChildGraph.Factory,
    calendarGraphFactory: CalendarChildGraph.Factory,
) : ComponentContext by componentContext {
    public val upNextPresenter: UpNextPresenter =
        upNextGraphFactory.createUpNextGraph(childContext(key = "UpNext")).upNextPresenter
    public val calendarPresenter: CalendarPresenter =
        calendarGraphFactory.createCalendarGraph(childContext(key = "Calendar")).calendarPresenter
}

When to use it

Use @ChildPresenter when a presenter is created and owned by a parent presenter rather than navigated to through a route. Tab-internal pagers, expanding-card sub-screens, and similar sub-components fit this pattern. Routed destinations should use @NavDestination instead.

Validation

The processor reports a compile error if any of the following hold:

• The annotated symbol is not a class.

• The presenter is parameterized but does not have exactly one @Assisted constructor parameter.