Struct EventReader 

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

Shared read access to the Events<T> resource.

Iterates over events sent by EventWriter<T> on the previous tick.

fn on_cannon_fired(reader: EventReader<'_, CannonFired>) {
    for ev in reader.read() {
        println!("cannon fired with power {}", ev.power);
    }
}

Implementations

impl<'w, T: Send + 'static> EventReader<'w, T>

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

Iterate over events from the previous tick.

pub fn len(&self) -> usize

Number of readable events.

pub fn is_empty(&self) -> bool

Returns true if there are no readable events.

Trait Implementations

impl<T: Send + 'static> SystemParam for EventReader<'_, T>

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

The concrete type produced for a given world lifetime.

fn access() -> Vec<Access>

Declare what world data this parameter accesses.

unsafe fn fetch<'w>(world: UnsafeWorldCell) -> Self::Item<'w>

Extract the parameter from the world.