Function bevy_ecs::schedule::common_conditions::resource_exists_and_equals
source · pub fn resource_exists_and_equals<T>(
value: T
) -> impl FnMut(Option<Res<'_, T>>) -> bool
Expand description
Generates a Condition
-satisfying closure that returns true
if the resource exists and is equal to value
.
The condition will return false
if the resource does not exist.
§Example
app.add_systems(
// `resource_exists_and_equals` will only return true
// if the given resource exists and equals the given value
my_system.run_if(resource_exists_and_equals(Counter(0))),
);
fn my_system(mut counter: ResMut<Counter>) {
counter.0 += 1;
}
// `Counter` hasn't been added so `my_system` can't run
app.run(&mut world);
world.init_resource::<Counter>();
// `Counter` is `0` so `my_system` can run
app.run(&mut world);
assert_eq!(world.resource::<Counter>().0, 1);
// `Counter` is no longer `0` so `my_system` won't run
app.run(&mut world);
assert_eq!(world.resource::<Counter>().0, 1);