Struct Events 

pub struct Events<T: 'static> { /* private fields */ }

Double-buffered typed event queue.

Events are written to current during the tick they are sent. At the start of the next Schedule::run(), World::update_events() swaps the buffers: current becomes previous and the old previous is cleared. Systems that use EventReader<T> iterate over previous, so they always read events from the previous tick.

Tick N:   EventWriter sends → current
tick N+1: update_events() → current becomes previous, cleared current
          EventReader reads previous (events from tick N)
Tick N+2: update_events() → previous is cleared

Register an event type with [World::add_event::<T>()] before using EventWriter<T> or EventReader<T> in systems.

Implementations

impl<T: 'static> Events<T>

pub fn new() -> Self

Create an empty double buffer.

pub fn send(&mut self, event: T)

Send an event. It will be readable by EventReader on the next tick.

pub fn read(&self) -> impl Iterator<Item = &T>

Iterate over events sent during the previous tick.

pub fn read_current(&self) -> impl Iterator<Item = &T>

Iterate over events in the current (not yet swapped) buffer.

For render extraction that runs after a tick completes: events sent during tick N live in current until the next update().

pub fn current_len(&self) -> usize

Number of events in the current (not yet swapped) buffer.

Used by render event extractors with offset tracking to avoid re-reading events that were already captured in a prior flush.

pub fn update(&mut self)

Advance the double buffer.

The previous buffer is cleared. The current buffer becomes the new previous buffer. Called automatically by World::update_events() at the start of each Schedule::run().

pub fn len(&self) -> usize

Number of readable events (in the previous buffer).

pub fn is_empty(&self) -> bool

Returns true if there are no readable events.

Trait Implementations

impl<T: 'static> Default for Events<T>

fn default() -> Self

Returns the “default value” for a type.