Struct bevy_ecs::removal_detection::RemovedComponents
source · pub struct RemovedComponents<'w, 's, T: Component> { /* private fields */ }
Expand description
A SystemParam
that yields entities that had their T
Component
removed or have been despawned with it.
This acts effectively the same as an EventReader
.
Note that this does not allow you to see which data existed before removal.
If you need this, you will need to track the component data value on your own,
using a regularly scheduled system that requests Query<(Entity, &T), Changed<T>>
and stores the data somewhere safe to later cross-reference.
If you are using bevy_ecs
as a standalone crate,
note that the RemovedComponents
list will not be automatically cleared for you,
and will need to be manually flushed using World::clear_trackers
.
For users of bevy
and bevy_app
, World::clear_trackers
is
automatically called by bevy_app::App::update
and bevy_app::SubApp::update
.
For the main world, this is delayed until after all SubApp
s have run.
§Examples
Basic usage:
fn react_on_removal(mut removed: RemovedComponents<MyComponent>) {
removed.read().for_each(|removed_entity| println!("{:?}", removed_entity));
}
Implementations§
source§impl<'w, 's, T: Component> RemovedComponents<'w, 's, T>
impl<'w, 's, T: Component> RemovedComponents<'w, 's, T>
sourcepub fn reader(&self) -> &ManualEventReader<RemovedComponentEntity>
pub fn reader(&self) -> &ManualEventReader<RemovedComponentEntity>
Fetch underlying ManualEventReader
.
sourcepub fn reader_mut(&mut self) -> &mut ManualEventReader<RemovedComponentEntity>
pub fn reader_mut(&mut self) -> &mut ManualEventReader<RemovedComponentEntity>
Fetch underlying ManualEventReader
mutably.
sourcepub fn reader_mut_with_events(
&mut self
) -> Option<(&mut RemovedComponentReader<T>, &Events<RemovedComponentEntity>)>
pub fn reader_mut_with_events( &mut self ) -> Option<(&mut RemovedComponentReader<T>, &Events<RemovedComponentEntity>)>
Destructures to get a mutable reference to the ManualEventReader
and a reference to Events
.
This is necessary since Rust can’t detect destructuring through methods and most
usecases of the reader uses the Events
as well.
sourcepub fn read(&mut self) -> RemovedIter<'_>
pub fn read(&mut self) -> RemovedIter<'_>
Iterates over the events this RemovedComponents
has not seen yet. This updates the
RemovedComponents
’s event counter, which means subsequent event reads will not include events
that happened before now.
sourcepub fn read_with_id(&mut self) -> RemovedIterWithId<'_>
pub fn read_with_id(&mut self) -> RemovedIterWithId<'_>
sourcepub fn len(&self) -> usize
pub fn len(&self) -> usize
Determines the number of removal events available to be read from this RemovedComponents
without consuming any.
sourcepub fn clear(&mut self)
pub fn clear(&mut self)
Consumes all available events.
This means these events will not appear in calls to RemovedComponents::read()
or
RemovedComponents::read_with_id()
and RemovedComponents::is_empty()
will return true
.
Trait Implementations§
source§impl<T: Component> SystemParam for RemovedComponents<'_, '_, T>
impl<T: Component> SystemParam for RemovedComponents<'_, '_, T>
§type Item<'w, 's> = RemovedComponents<'w, 's, T>
type Item<'w, 's> = RemovedComponents<'w, 's, T>
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
World
access used by this SystemParam
and creates a new instance of this param’s State
.source§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 )
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)
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<'_> )
apply_deferred
.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>
SystemParamFunction
. Read moreimpl<'w, 's, T: Component> ReadOnlySystemParam for RemovedComponents<'w, 's, T>where
ComponentIdFor<'s, T>: ReadOnlySystemParam,
Local<'s, RemovedComponentReader<T>>: ReadOnlySystemParam,
&'w RemovedComponentEvents: ReadOnlySystemParam,
Auto Trait Implementations§
impl<'w, 's, T> Freeze for RemovedComponents<'w, 's, T>
impl<'w, 's, T> RefUnwindSafe for RemovedComponents<'w, 's, T>where
T: RefUnwindSafe,
impl<'w, 's, T> Send for RemovedComponents<'w, 's, T>
impl<'w, 's, T> Sync for RemovedComponents<'w, 's, T>
impl<'w, 's, T> Unpin for RemovedComponents<'w, 's, T>
impl<'w, 's, T> !UnwindSafe for RemovedComponents<'w, '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
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>
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>
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)
&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)
&mut Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &mut Any
’s vtable from &mut Trait
’s.