pub struct Single<'w, 's, D: QueryData, F: QueryFilter = ()> { /* private fields */ }
Expand description
System parameter that provides access to single entity’s components, much like Query::single
/Query::single_mut
.
This SystemParam
fails validation if zero or more than one matching entity exists.
This will cause the system to be skipped, according to the rules laid out in SystemParamValidationError
.
Use Option<Single<D, F>>
instead if zero or one matching entities can exist.
See Query
for more details.
§Example
#[derive(Component)]
struct Boss {
health: f32
};
fn hurt_boss(mut boss: Single<&mut Boss>) {
boss.health -= 4.0;
}
Note that because Single
implements Deref
and DerefMut
, methods and fields like health
can be accessed directly.
You can also access the underlying data manually, by calling .deref
/.deref_mut
, or by using the *
operator.
Implementations§
Source§impl<'w, 's, D: QueryData, F: QueryFilter> Single<'w, 's, D, F>
impl<'w, 's, D: QueryData, F: QueryFilter> Single<'w, 's, D, F>
Sourcepub fn into_inner(self) -> D::Item<'w, 's>
pub fn into_inner(self) -> D::Item<'w, 's>
Returns the inner item with ownership.
Trait Implementations§
Source§impl<'a, 'b, D: QueryData + 'static, F: QueryFilter + 'static> SystemParam for Single<'a, 'b, D, F>
impl<'a, 'b, D: QueryData + 'static, F: QueryFilter + 'static> SystemParam for Single<'a, 'b, D, F>
Source§type State = QueryState<D, F>
type State = QueryState<D, F>
Used to store data which persists across invocations of a system.
Source§type Item<'w, 's> = Single<'w, 's, D, F>
type Item<'w, 's> = Single<'w, 's, D, F>
The item type returned when constructing this system param.
The value of this associated type should be
Self
, instantiated with new lifetimes. Read moreSource§fn init_access(
state: &Self::State,
system_meta: &mut SystemMeta,
component_access_set: &mut FilteredAccessSet,
world: &mut World,
)
fn init_access( state: &Self::State, system_meta: &mut SystemMeta, component_access_set: &mut FilteredAccessSet, world: &mut World, )
Registers any
World
access used by this SystemParam
Source§unsafe fn get_param<'w, 's>(
state: &'s mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'w>,
change_tick: Tick,
) -> Self::Item<'w, 's>
unsafe fn get_param<'w, 's>( state: &'s mut Self::State, system_meta: &SystemMeta, world: UnsafeWorldCell<'w>, change_tick: Tick, ) -> Self::Item<'w, 's>
Creates a parameter to be passed into a
SystemParamFunction
. Read moreSource§unsafe fn validate_param(
state: &mut Self::State,
system_meta: &SystemMeta,
world: UnsafeWorldCell<'_>,
) -> Result<(), SystemParamValidationError>
unsafe fn validate_param( state: &mut Self::State, system_meta: &SystemMeta, world: UnsafeWorldCell<'_>, ) -> Result<(), SystemParamValidationError>
Source§fn apply(state: &mut Self::State, system_meta: &SystemMeta, world: &mut World)
fn apply(state: &mut Self::State, system_meta: &SystemMeta, world: &mut World)
Applies any deferred mutations stored in this
SystemParam
’s state.
This is used to apply Commands
during ApplyDeferred
.Source§fn queue(
state: &mut Self::State,
system_meta: &SystemMeta,
world: DeferredWorld<'_>,
)
fn queue( state: &mut Self::State, system_meta: &SystemMeta, world: DeferredWorld<'_>, )
Queues any deferred mutations to be applied at the next
ApplyDeferred
.impl<'a, 'b, D: ReadOnlyQueryData + 'static, F: QueryFilter + 'static> ReadOnlySystemParam for Single<'a, 'b, D, F>
Auto Trait Implementations§
impl<'w, 's, D, F> Freeze for Single<'w, 's, D, F>
impl<'w, 's, D, F> RefUnwindSafe for Single<'w, 's, D, F>
impl<'w, 's, D, F> Send for Single<'w, 's, D, F>
impl<'w, 's, D, F> Sync for Single<'w, 's, D, F>
impl<'w, 's, D, F> Unpin for Single<'w, 's, D, F>
impl<'w, 's, D, F> UnwindSafe for Single<'w, 's, D, F>
Blanket Implementations§
Source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
Source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
Source§impl<T> Downcast for Twhere
T: Any,
impl<T> Downcast for Twhere
T: Any,
Source§fn into_any(self: Box<T>) -> Box<dyn Any>
fn into_any(self: Box<T>) -> Box<dyn Any>
Converts
Box<dyn Trait>
(where Trait: Downcast
) to Box<dyn Any>
, which can then be
downcast
into Box<dyn ConcreteType>
where ConcreteType
implements Trait
.Source§fn into_any_rc(self: Rc<T>) -> Rc<dyn Any>
fn into_any_rc(self: Rc<T>) -> Rc<dyn Any>
Converts
Rc<Trait>
(where Trait: Downcast
) to Rc<Any>
, which can then be further
downcast
into Rc<ConcreteType>
where ConcreteType
implements Trait
.Source§fn as_any(&self) -> &(dyn Any + 'static)
fn as_any(&self) -> &(dyn Any + 'static)
Converts
&Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &Any
’s vtable from &Trait
’s.Source§fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
Converts
&mut Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &mut Any
’s vtable from &mut Trait
’s.Source§impl<T> DowncastSend for T
impl<T> DowncastSend for T
Source§impl<T> Instrument for T
impl<T> Instrument for T
Source§fn instrument(self, span: Span) -> Instrumented<Self>
fn instrument(self, span: Span) -> Instrumented<Self>
Source§fn in_current_span(self) -> Instrumented<Self>
fn in_current_span(self) -> Instrumented<Self>
Source§impl<T> IntoResult<T> for T
impl<T> IntoResult<T> for T
Source§fn into_result(self) -> Result<T, RunSystemError>
fn into_result(self) -> Result<T, RunSystemError>
Converts this type into the system output type.
Source§impl<R> Rng for R
impl<R> Rng for R
Source§fn random<T>(&mut self) -> Twhere
StandardUniform: Distribution<T>,
fn random<T>(&mut self) -> Twhere
StandardUniform: Distribution<T>,
Return a random value via the
StandardUniform
distribution. Read moreSource§fn random_iter<T>(self) -> Iter<StandardUniform, Self, T>
fn random_iter<T>(self) -> Iter<StandardUniform, Self, T>
Source§fn random_range<T, R>(&mut self, range: R) -> Twhere
T: SampleUniform,
R: SampleRange<T>,
fn random_range<T, R>(&mut self, range: R) -> Twhere
T: SampleUniform,
R: SampleRange<T>,
Generate a random value in the given range. Read more
Source§fn random_bool(&mut self, p: f64) -> bool
fn random_bool(&mut self, p: f64) -> bool
Return a bool with a probability
p
of being true. Read moreSource§fn random_ratio(&mut self, numerator: u32, denominator: u32) -> bool
fn random_ratio(&mut self, numerator: u32, denominator: u32) -> bool
Return a bool with a probability of
numerator/denominator
of being
true. Read moreSource§fn sample<T, D>(&mut self, distr: D) -> Twhere
D: Distribution<T>,
fn sample<T, D>(&mut self, distr: D) -> Twhere
D: Distribution<T>,
Sample a new value, using the given distribution. Read more
Source§fn sample_iter<T, D>(self, distr: D) -> Iter<D, Self, T>where
D: Distribution<T>,
Self: Sized,
fn sample_iter<T, D>(self, distr: D) -> Iter<D, Self, T>where
D: Distribution<T>,
Self: Sized,
Create an iterator that generates values using the given distribution. Read more
Source§fn gen<T>(&mut self) -> Twhere
StandardUniform: Distribution<T>,
fn gen<T>(&mut self) -> Twhere
StandardUniform: Distribution<T>,
👎Deprecated since 0.9.0: Renamed to
random
to avoid conflict with the new gen
keyword in Rust 2024.Alias for
Rng::random
.Source§fn gen_range<T, R>(&mut self, range: R) -> Twhere
T: SampleUniform,
R: SampleRange<T>,
fn gen_range<T, R>(&mut self, range: R) -> Twhere
T: SampleUniform,
R: SampleRange<T>,
👎Deprecated since 0.9.0: Renamed to
random_range
Alias for
Rng::random_range
.Source§impl<R> TryRngCore for R
impl<R> TryRngCore for R
Source§type Error = Infallible
type Error = Infallible
The type returned in the event of a RNG error.
Source§fn try_next_u32(&mut self) -> Result<u32, <R as TryRngCore>::Error>
fn try_next_u32(&mut self) -> Result<u32, <R as TryRngCore>::Error>
Return the next random
u32
.Source§fn try_next_u64(&mut self) -> Result<u64, <R as TryRngCore>::Error>
fn try_next_u64(&mut self) -> Result<u64, <R as TryRngCore>::Error>
Return the next random
u64
.Source§fn try_fill_bytes(
&mut self,
dst: &mut [u8],
) -> Result<(), <R as TryRngCore>::Error>
fn try_fill_bytes( &mut self, dst: &mut [u8], ) -> Result<(), <R as TryRngCore>::Error>
Fill
dest
entirely with random data.Source§fn unwrap_mut(&mut self) -> UnwrapMut<'_, Self>
fn unwrap_mut(&mut self) -> UnwrapMut<'_, Self>
Wrap RNG with the
UnwrapMut
wrapper.Source§fn read_adapter(&mut self) -> RngReadAdapter<'_, Self>where
Self: Sized,
fn read_adapter(&mut self) -> RngReadAdapter<'_, Self>where
Self: Sized,
Convert an
RngCore
to a RngReadAdapter
.