Struct EventReader 

pub struct EventReader<'a, T>
where
    T: Clone + Send + Sync + 'static,
{ /* private fields */ }

A system parameter that reads events of type T from the host’s event bus, delivering each event to this system exactly once across frames. The reader keeps its own cursor in the runner, so two systems reading the same event type advance independently and neither disturbs the bus’s two-frame buffer. Events are copied out for the run, so T is Clone, and a Query in the same system borrows the world freely alongside it.

Implementations

impl<T> EventReader<'_, T>

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

pub fn iter(&self) -> Iter<'_, T>

Visits the events delivered to this reader this run, oldest first.

pub fn len(&self) -> usize

The number of events delivered to this reader this run.

pub fn is_empty(&self) -> bool

Whether no events were delivered to this reader this run.

Trait Implementations

impl<W, T> ExtractParam<W> for EventReader<'_, T>

where W: EventHost, T: Clone + Send + Sync + 'static,

type State = u64

Per-system state kept in the runner across runs.

type Owned = Vec<T>

The owned value produced for one run; the parameter borrows it.

type Item<'item> = EventReader<'item, T>

The parameter value handed to the system for a given borrow.

fn init() -> u64

The initial state for a freshly registered system.

fn extract(state: &mut u64, host: &mut W) -> Vec<T>

Lifts the owned value out of the host before the run.

fn build(owned: &mut Vec<T>) -> EventReader<'_, T>

Wraps the owned value as the parameter value.

fn apply(_state: &mut u64, _owned: Vec<T>, _host: &mut W)

Writes back after the run: a resource returns to the map, buffered events flush to the bus, a reader does nothing.

impl<'a, T> IntoIterator for &'a EventReader<'_, T>

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

type Item = &'a T

The type of the elements being iterated over.

type IntoIter = Iter<'a, T>

Which kind of iterator are we turning this into?

fn into_iter(self) -> <&'a EventReader<'_, T> as IntoIterator>::IntoIter

Creates an iterator from a value.