Struct Res

pub struct Res<'w, T: ?Sized + Resource> { /* private fields */ }

Shared borrow of a Resource.

See the Resource documentation for usage.

If you need a unique mutable borrow, use ResMut instead.

This SystemParam fails validation if resource doesn’t exist. This will cause systems that use this parameter to be skipped.

Use Option<Res<T>> instead if the resource might not always exist.

Implementations

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

pub fn clone(this: &Self) -> Self

Copies a reference to a resource.

Note that unless you actually need an instance of Res<T>, you should prefer to just convert it to &T which can be freely copied.

pub fn into_inner(self) -> &'w T

Due to lifetime limitations of the Deref trait, this method can be used to obtain a reference of the Resource with a lifetime bound to 'w instead of the lifetime of the struct itself.

Trait Implementations

impl<'w, T: Resource> AsRef<T> for Res<'w, T>

fn as_ref(&self) -> &T

Converts this type into a shared reference of the (usually inferred) input type.

impl<'w, T> Debug for Res<'w, T>

where T: Debug + ?Sized + Resource,

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

Formats the value using the given formatter.

impl<'w, T: ?Sized + Resource> Deref for Res<'w, T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<'w, T: ?Sized + Resource> DetectChanges for Res<'w, T>

fn is_added(&self) -> bool

Returns true if this value was added after the system last ran.

fn is_changed(&self) -> bool

Returns true if this value was added or mutably dereferenced either since the last time the system ran or, if the system never ran, since the beginning of the program.

fn last_changed(&self) -> Tick

Returns the change tick recording the time this data was most recently changed.

impl<'w, T: Resource> From<Res<'w, T>> for Ref<'w, T>

fn from(res: Res<'w, T>) -> Self

Convert a Res into a Ref. This allows keeping the change-detection feature of Ref while losing the specificity of Res for resources.

impl<'w, T: Resource> From<ResMut<'w, T>> for Res<'w, T>

fn from(res: ResMut<'w, T>) -> Self

Converts to this type from the input type.

impl<'w, 'a, T: Resource> IntoIterator for &'a Res<'w, T>

where &'a T: IntoIterator,

type Item = <&'a T as IntoIterator>::Item

The type of the elements being iterated over.

type IntoIter = <&'a T as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<'a, T: Resource> SystemParam for Res<'a, T>

type State = ComponentId

Used to store data which persists across invocations of a system.

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

The item type returned when constructing this system param. The value of this associated type should be Self, instantiated with new lifetimes.

fn init_state(world: &mut World, system_meta: &mut SystemMeta) -> Self::State

Registers any World access used by this SystemParam and creates a new instance of this param’s State.

unsafe fn validate_param( component_id: &Self::State, system_meta: &SystemMeta, world: UnsafeWorldCell<'_>, ) -> bool

Validates that the param can be acquired by the get_param. Built-in executors use this to prevent systems with invalid params from running. For nested SystemParams validation will fail if any delegated validation fails.

unsafe fn get_param<'w, 's>( component_id: &'s mut Self::State, system_meta: &SystemMeta, world: UnsafeWorldCell<'w>, change_tick: Tick, ) -> Self::Item<'w, 's>

Creates a parameter to be passed into a SystemParamFunction.

unsafe fn new_archetype( state: &mut Self::State, archetype: &Archetype, system_meta: &mut SystemMeta, )

For the specified Archetype, registers the components accessed by this SystemParam (if applicable).a

fn apply(state: &mut Self::State, system_meta: &SystemMeta, world: &mut World)

Applies any deferred mutations stored in this SystemParam’s state. This is used to apply Commands during apply_deferred.

fn queue( state: &mut Self::State, system_meta: &SystemMeta, world: DeferredWorld<'_>, )

Queues any deferred mutations to be applied at the next apply_deferred.

impl<'a, T: Resource> ReadOnlySystemParam for Res<'a, T>