Struct Read 

pub struct Read<'a, T: 'a, F = DefaultSetupHandler> { /* private fields */ }

Allows to fetch a resource in a system immutably.

If the resource isn’t strictly required, you should use Option<Read<T>>.

Type parameters

• T: The type of the resource
• F: The setup handler (default: DefaultProvider)

Implementations

impl<'a, T, F> Read<'a, T, F>

pub fn new(inner: Ref<'a, T>) -> Self

Trait Implementations

impl<'a, T, F> Deref for Read<'a, T, F>

where T: Resource,

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<'a, T, F> From<Ref<'a, T>> for Read<'a, T, F>

fn from(inner: Ref<'a, T>) -> Self

Converts to this type from the input type.

impl<'a, 'b, T> Join for &'a Read<'b, T>

where &'a T: Join, T: Resource,

type Type = <&'a T as Join>::Type

Type of joined components.

type Value = <&'a T as Join>::Value

Type of joined storages.

type Mask = <&'a T as Join>::Mask

Type of joined bit mask.

unsafe fn open(self) -> (Self::Mask, Self::Value)

Open this join by returning the mask and the storages.

unsafe fn get(v: &mut Self::Value, i: Index) -> Self::Type

Get a joined component value by a given index.

fn is_unconstrained() -> bool

If this Join typically returns all indices in the mask, then iterating over only it or combined with other joins that are also dangerous will cause the JoinIter/ParJoin to go through all indices which is usually not what is wanted and will kill performance.

fn join(self) -> JoinIter<Self>

where Self: Sized,

Create a joined iterator over the contents.

fn maybe(self) -> MaybeJoin<Self>

where Self: Sized,

Returns a Join-able structure that yields all indices, returning None for all missing elements and Some(T) for found elements.

impl<'a, 'b, T> ParJoin for &'a Read<'b, T>

where &'a T: ParJoin, T: Resource,

fn par_join(self) -> JoinParIter<Self>

where Self: Sized,

impl<'a, T, F> SystemData<'a> for Read<'a, T, F>

where T: Resource, F: SetupHandler<T>,

fn setup(world: &mut World)

Sets up the system data for fetching it from the World.

fn fetch(world: &'a World) -> Self

Fetches the system data from World. Note that this is only specified for one concrete lifetime 'a, you need to implement the SystemData trait for every possible lifetime.

fn reads() -> Vec<ResourceId>

Returns all read dependencies as fetched from Self::fetch.

fn writes() -> Vec<ResourceId>

Returns all write dependencies as fetched from Self::fetch.