mirror of
https://github.com/bevyengine/bevy
synced 2024-11-26 22:50:19 +00:00
89cbc78d3d
# Objective Be consistent with `Resource`s and `Components` and have `Event` types be more self-documenting. Although not susceptible to accidentally using a function instead of a value due to `Event`s only being initialized by their type, much of the same reasoning for removing the blanket impl on `Resource` also applies here. * Not immediately obvious if a type is intended to be an event * Prevent invisible conflicts if the same third-party or primitive types are used as events * Allows for further extensions (e.g. opt-in warning for missed events) ## Solution Remove the blanket impl for the `Event` trait. Add a derive macro for it. --- ## Changelog - `Event` is no longer implemented for all applicable types. Add the `#[derive(Event)]` macro for events. ## Migration Guide * Add the `#[derive(Event)]` macro for events. Third-party types used as events should be wrapped in a newtype.
63 lines
1.5 KiB
Rust
63 lines
1.5 KiB
Rust
//! This example creates a new event, a system that triggers the event once per second,
|
|
//! and a system that prints a message whenever the event is received.
|
|
|
|
use bevy::prelude::*;
|
|
|
|
fn main() {
|
|
App::new()
|
|
.add_plugins(DefaultPlugins)
|
|
.add_event::<MyEvent>()
|
|
.add_event::<PlaySound>()
|
|
.init_resource::<EventTriggerState>()
|
|
.add_systems(Update, (event_trigger, event_listener, sound_player))
|
|
.run();
|
|
}
|
|
|
|
#[derive(Event)]
|
|
struct MyEvent {
|
|
pub message: String,
|
|
}
|
|
|
|
#[derive(Event, Default)]
|
|
struct PlaySound;
|
|
|
|
#[derive(Resource)]
|
|
struct EventTriggerState {
|
|
event_timer: Timer,
|
|
}
|
|
|
|
impl Default for EventTriggerState {
|
|
fn default() -> Self {
|
|
EventTriggerState {
|
|
event_timer: Timer::from_seconds(1.0, TimerMode::Repeating),
|
|
}
|
|
}
|
|
}
|
|
|
|
// sends MyEvent and PlaySound every second
|
|
fn event_trigger(
|
|
time: Res<Time>,
|
|
mut state: ResMut<EventTriggerState>,
|
|
mut my_events: EventWriter<MyEvent>,
|
|
mut play_sound_events: EventWriter<PlaySound>,
|
|
) {
|
|
if state.event_timer.tick(time.delta()).finished() {
|
|
my_events.send(MyEvent {
|
|
message: "MyEvent just happened!".to_string(),
|
|
});
|
|
play_sound_events.send_default();
|
|
}
|
|
}
|
|
|
|
// prints events as they come in
|
|
fn event_listener(mut events: EventReader<MyEvent>) {
|
|
for my_event in events.iter() {
|
|
info!("{}", my_event.message);
|
|
}
|
|
}
|
|
|
|
fn sound_player(mut play_sound_events: EventReader<PlaySound>) {
|
|
for _ in play_sound_events.iter() {
|
|
info!("Playing a sound");
|
|
}
|
|
}
|