pub struct Local<'s, T: FromWorld + Send + 'static>(/* private fields */);
Expand description
A system local SystemParam
.
A local may only be accessed by the system itself and is therefore not visible to other systems.
If two or more systems specify the same local type each will have their own unique local.
If multiple SystemParam
s within the same system each specify the same local type
each will get their own distinct data storage.
The supplied lifetime parameter is the SystemParam
s 's
lifetime.
§Examples
fn write_to_local(mut local: Local<usize>) {
*local = 42;
}
fn read_from_local(local: Local<usize>) -> usize {
*local
}
let mut write_system = IntoSystem::into_system(write_to_local);
let mut read_system = IntoSystem::into_system(read_from_local);
write_system.initialize(world);
read_system.initialize(world);
assert_eq!(read_system.run((), world), 0);
write_system.run((), world);
// Note how the read local is still 0 due to the locals not being shared.
assert_eq!(read_system.run((), world), 0);
N.B. A Local
s value cannot be read or written to outside of the containing system.
To add configuration to a system, convert a capturing closure into the system instead:
struct Config(u32);
#[derive(Resource)]
struct MyU32Wrapper(u32);
fn reset_to_system(value: Config) -> impl FnMut(ResMut<MyU32Wrapper>) {
move |mut val| val.0 = value.0
}
// .add_systems(reset_to_system(my_config))
Trait Implementations§
source§impl<'_s, T: FromWorld + Send + 'static> ExclusiveSystemParam for Local<'_s, T>
impl<'_s, T: FromWorld + Send + 'static> ExclusiveSystemParam for Local<'_s, T>
§type Item<'s> = Local<'s, T>
type Item<'s> = Local<'s, T>
The item type returned when constructing this system param.
See
SystemParam::Item
.source§fn init(world: &mut World, _system_meta: &mut SystemMeta) -> Self::State
fn init(world: &mut World, _system_meta: &mut SystemMeta) -> Self::State
Creates a new instance of this param’s
State
.source§fn get_param<'s>(
state: &'s mut Self::State,
_system_meta: &SystemMeta
) -> Self::Item<'s>
fn get_param<'s>( state: &'s mut Self::State, _system_meta: &SystemMeta ) -> Self::Item<'s>
Creates a parameter to be passed into an
ExclusiveSystemParamFunction
.source§impl<'s, 'a, T: FromWorld + Send + 'static> IntoIterator for &'a Local<'s, T>where
&'a T: IntoIterator,
impl<'s, 'a, T: FromWorld + Send + 'static> IntoIterator for &'a Local<'s, T>where
&'a T: IntoIterator,
source§impl<'s, 'a, T: FromWorld + Send + 'static> IntoIterator for &'a mut Local<'s, T>where
&'a mut T: IntoIterator,
impl<'s, 'a, T: FromWorld + Send + 'static> IntoIterator for &'a mut Local<'s, T>where
&'a mut T: IntoIterator,
source§impl<'a, T: FromWorld + Send + 'static> SystemParam for Local<'a, T>
impl<'a, T: FromWorld + Send + 'static> SystemParam for Local<'a, T>
§type Item<'w, 's> = Local<'s, T>
type Item<'w, 's> = Local<'s, T>
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_state(world: &mut World, _system_meta: &mut SystemMeta) -> Self::State
fn init_state(world: &mut World, _system_meta: &mut SystemMeta) -> Self::State
Registers any
World
access used by this SystemParam
and creates a new instance of this param’s State
.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 new_archetype(
state: &mut Self::State,
archetype: &Archetype,
system_meta: &mut SystemMeta
)
unsafe fn new_archetype( state: &mut Self::State, archetype: &Archetype, system_meta: &mut SystemMeta )
For the specified
Archetype
, registers the components accessed by this SystemParam
(if applicable).a Read moresource§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 apply_deferred
.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
apply_deferred
.impl<'s, T: FromWorld + Send + 'static> ReadOnlySystemParam for Local<'s, T>
Auto Trait Implementations§
impl<'s, T> Freeze for Local<'s, T>
impl<'s, T> RefUnwindSafe for Local<'s, T>where
T: RefUnwindSafe,
impl<'s, T> Send for Local<'s, T>
impl<'s, T> Sync for Local<'s, T>where
T: Sync,
impl<'s, T> Unpin for Local<'s, T>
impl<'s, T> !UnwindSafe for Local<'s, T>
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>
Convert
Box<dyn Trait>
(where Trait: Downcast
) to Box<dyn Any>
. Box<dyn Any>
can
then be further downcast
into Box<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>
Convert
Rc<Trait>
(where Trait: Downcast
) to Rc<Any>
. Rc<Any>
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)
Convert
&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)
Convert
&mut Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &mut Any
’s vtable from &mut Trait
’s.