Struct Res 

pub struct Res<'w, T: 'static> { /* private fields */ }

Shared reference to a resource in World.

Analogous to Bevy’s Res<T>.

Appears in handler function signatures to declare a read dependency. Derefs to the inner value transparently. Carries change-detection metadata — call is_changed to check.

For exclusive write access, use ResMut<T>. For optional read access (no panic if unregistered), use Option<Res<T>>.

Construction is pub(crate) — only the dispatch layer creates these.

Implementations

impl<'w, T: 'static> Res<'w, T>

pub fn is_changed(&self) -> bool

Returns true if the resource was modified during the current sequence.

pub fn changed_after(&self, since: Sequence) -> bool

Returns true if the resource was modified after since.

Unlike is_changed (equality check against current sequence), this uses > — suitable for checking whether any event since a prior checkpoint wrote this resource.

Relies on numeric ordering of the underlying u64 counter. Not wrap-safe, but at one increment per event the u64 sequence space takes ~584 years at 1 GHz to exhaust.

Trait Implementations

impl<T: Debug + 'static> Debug for Res<'_, T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: 'static> Deref for Res<'_, T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T: 'static> Param for Res<'_, T>

type State = ResourceId

Opaque state cached at build time (e.g. ResourceId).

type Item<'w> = Res<'w, T>

The item produced at dispatch time.

fn init(registry: &Registry) -> ResourceId

Resolve state from the registry. Called once at build time.

unsafe fn fetch<'w>(world: &'w World, state: &'w mut ResourceId) -> Res<'w, T>

Fetch the item using cached state.

fn resource_id(state: &ResourceId) -> Option<ResourceId>

The ResourceId this param accesses, if any.