Struct Context 

pub struct Context { /* private fields */ }

Per-component context passed to every [Component::build] call.

Carries the component’s identity and provides access to persistent local state via Context::state. State is keyed by (component_id, call_order) — the hook model — so call order within build() must be stable across frames.

Implementations

impl Context

pub fn new(id: ComponentId) -> Self

pub fn component_id(&self) -> ComponentId

pub fn state<T: Clone + Send + Sync + 'static>(&mut self, default: T) -> Atom<T>

Returns a persistent Atom<T> for local component state.

On first call per slot the atom is seeded with default. On subsequent frames the existing atom is returned, preserving the last value.

pub fn state_permanent<T>(&mut self, key: &str, default: T) -> Atom<T>

where T: PersistValue + Clone + Send + Sync + 'static,

D008’s permanent tier, on the hook model (D114/D121): like Context::state, but the FIRST initialization reads key from the installed persist backend (falling back to default if the key is absent or its bytes are stale), and every later set writes through — the value survives a full app restart.

key is app-global: two components using the same key share the same stored value (by design — it’s a storage key, not a hook slot). With no backend installed (headless tests, or before App::launch) this behaves exactly like plain Context::state.

Uses the atom’s single on_change slot for the write-through — see Atom::set_on_change’s doc.

pub fn on_cleanup(&mut self, f: impl FnOnce() + Send + 'static)

Registers a cleanup function that runs when this component unmounts.

Stored in the persistent rosace_state::cleanup_store keyed by component ID. The reconciler fires these callbacks when the component disappears from the element tree.