Struct Res 

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

Shared reference to a resource in World.

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

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.

Trait Implementations

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> SystemParam 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 any_changed(state: &ResourceId, world: &World) -> bool

Returns true if any resource this param depends on was modified during the current sequence.

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

The ResourceId this param accesses, if any.