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# Objective I noticed a few typos in these docs recently. ## Solution Minimal fixes so that these sentences make sense.
1.5 KiB
1.5 KiB
B0002
To keep Rust rules on references (either one mutable reference or any number of immutable references) on a resource, it is not possible to have more than one resource of a kind if one is mutable in the same system. This can happen between Res<T>
and ResMut<T>
for the same T
, or between NonSend<T>
and NonSendMut<T>
for the same T
.
Erroneous code example:
use bevy::prelude::*;
fn update_materials(
mut material_updater: ResMut<Assets<StandardMaterial>>,
current_materials: Res<Assets<StandardMaterial>>,
) {
// ...
}
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Update, update_materials)
.run();
}
This will panic, as it's not possible to have both a mutable and an immutable resource on Assets<StandardMaterial>
at the same time.
As a mutable resource already provides access to the current resource value, so you can remove the immutable resource.
use bevy::prelude::*;
fn update_materials(
mut material_updater: ResMut<Assets<StandardMaterial>>,
) {
// ...
}
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Update, update_materials)
.run();
}