Struct bevy_ecs::system::ParamSet

pub struct ParamSet<'w, 's, T: SystemParam> { /* private fields */ }

A collection of potentially conflicting SystemParams allowed by disjoint access.

Allows systems to safely access and interact with up to 8 mutually exclusive SystemParams, such as two queries that reference the same mutable data or an event reader and writer of the same type.

Each individual SystemParam can be accessed by using the functions p0(), p1(), …, p7(), according to the order they are defined in the ParamSet. This ensures that there’s either only one mutable reference to a parameter at a time or any number of immutable references.

Examples

The following system mutably accesses the same component two times, which is not allowed due to rust’s mutability rules.

// This will panic at runtime when the system gets initialized.
fn bad_system(
    mut enemies: Query<&mut Health, With<Enemy>>,
    mut allies: Query<&mut Health, With<Ally>>,
) {
    // ...
}

Conflicting SystemParams like these can be placed in a ParamSet, which leverages the borrow checker to ensure that only one of the contained parameters are accessed at a given time.

// Given the following system
fn fancy_system(
    mut set: ParamSet<(
        Query<&mut Health, With<Enemy>>,
        Query<&mut Health, With<Ally>>,
    )>
) {
    // This will access the first `SystemParam`.
    for mut health in set.p0().iter_mut() {
        // Do your fancy stuff here...
    }

    // The second `SystemParam`.
    // This would fail to compile if the previous parameter was still borrowed.
    for mut health in set.p1().iter_mut() {
        // Do even fancier stuff here...
    }
}

Of course, ParamSets can be used with any kind of SystemParam, not just queries.

fn event_system(
    mut set: ParamSet<(
        // `EventReader`s and `EventWriter`s conflict with each other,
        // since they both access the event queue resource for `MyEvent`.
        EventReader<MyEvent>,
        EventWriter<MyEvent>,
        // `&World` reads the entire world, so a `ParamSet` is the only way
        // that it can be used in the same system as any mutable accesses.
        &World,
    )>,
) {
    for event in set.p0().read() {
        // ...
    }
    set.p1().send(MyEvent::new());
     
    let entities = set.p2().entities();
    // ...
}

Implementations

impl<'w, 's, P0: SystemParam> ParamSet<'w, 's, (P0,)>

pub fn p0<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P0>

Gets exclusive access to the 0th parameter in this ParamSet. No other parameters may be accessed while this one is active.

impl<'w, 's, P0: SystemParam, P1: SystemParam> ParamSet<'w, 's, (P0, P1)>

pub fn p0<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P0>

Gets exclusive access to the 0th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p1<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P1>

Gets exclusive access to the 1st parameter in this ParamSet. No other parameters may be accessed while this one is active.

impl<'w, 's, P0: SystemParam, P1: SystemParam, P2: SystemParam> ParamSet<'w, 's, (P0, P1, P2)>

pub fn p0<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P0>

Gets exclusive access to the 0th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p1<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P1>

Gets exclusive access to the 1st parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p2<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P2>

Gets exclusive access to the 2nd parameter in this ParamSet. No other parameters may be accessed while this one is active.

impl<'w, 's, P0: SystemParam, P1: SystemParam, P2: SystemParam, P3: SystemParam> ParamSet<'w, 's, (P0, P1, P2, P3)>

pub fn p0<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P0>

Gets exclusive access to the 0th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p1<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P1>

Gets exclusive access to the 1st parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p2<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P2>

Gets exclusive access to the 2nd parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p3<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P3>

Gets exclusive access to the 3rd parameter in this ParamSet. No other parameters may be accessed while this one is active.

impl<'w, 's, P0: SystemParam, P1: SystemParam, P2: SystemParam, P3: SystemParam, P4: SystemParam> ParamSet<'w, 's, (P0, P1, P2, P3, P4)>

pub fn p0<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P0>

Gets exclusive access to the 0th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p1<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P1>

Gets exclusive access to the 1st parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p2<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P2>

Gets exclusive access to the 2nd parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p3<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P3>

Gets exclusive access to the 3rd parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p4<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P4>

Gets exclusive access to the 4th parameter in this ParamSet. No other parameters may be accessed while this one is active.

impl<'w, 's, P0: SystemParam, P1: SystemParam, P2: SystemParam, P3: SystemParam, P4: SystemParam, P5: SystemParam> ParamSet<'w, 's, (P0, P1, P2, P3, P4, P5)>

pub fn p0<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P0>

Gets exclusive access to the 0th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p1<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P1>

Gets exclusive access to the 1st parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p2<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P2>

Gets exclusive access to the 2nd parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p3<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P3>

Gets exclusive access to the 3rd parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p4<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P4>

Gets exclusive access to the 4th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p5<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P5>

Gets exclusive access to the 5th parameter in this ParamSet. No other parameters may be accessed while this one is active.

impl<'w, 's, P0: SystemParam, P1: SystemParam, P2: SystemParam, P3: SystemParam, P4: SystemParam, P5: SystemParam, P6: SystemParam> ParamSet<'w, 's, (P0, P1, P2, P3, P4, P5, P6)>

pub fn p0<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P0>

Gets exclusive access to the 0th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p1<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P1>

Gets exclusive access to the 1st parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p2<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P2>

Gets exclusive access to the 2nd parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p3<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P3>

Gets exclusive access to the 3rd parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p4<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P4>

Gets exclusive access to the 4th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p5<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P5>

Gets exclusive access to the 5th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p6<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P6>

Gets exclusive access to the 6th parameter in this ParamSet. No other parameters may be accessed while this one is active.

impl<'w, 's, P0: SystemParam, P1: SystemParam, P2: SystemParam, P3: SystemParam, P4: SystemParam, P5: SystemParam, P6: SystemParam, P7: SystemParam> ParamSet<'w, 's, (P0, P1, P2, P3, P4, P5, P6, P7)>

pub fn p0<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P0>

Gets exclusive access to the 0th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p1<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P1>

Gets exclusive access to the 1st parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p2<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P2>

Gets exclusive access to the 2nd parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p3<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P3>

Gets exclusive access to the 3rd parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p4<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P4>

Gets exclusive access to the 4th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p5<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P5>

Gets exclusive access to the 5th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p6<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P6>

Gets exclusive access to the 6th parameter in this ParamSet. No other parameters may be accessed while this one is active.

pub fn p7<'a>(&'a mut self) -> SystemParamItem<'a, 'a, P7>

Gets exclusive access to the 7th parameter in this ParamSet. No other parameters may be accessed while this one is active.

Trait Implementations

impl<'_w, '_s, P0: SystemParam> SystemParam for ParamSet<'_w, '_s, (P0,)>

type State = (<P0 as SystemParam>::State,)

Used to store data which persists across invocations of a system.

type Item<'w, 's> = ParamSet<'w, 's, (P0,)>

The item type returned when constructing this system param. The value of this associated type should be Self, instantiated with new lifetimes.

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.

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).

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.

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.

impl<'_w, '_s, P0: SystemParam, P1: SystemParam> SystemParam for ParamSet<'_w, '_s, (P0, P1)>

type State = (<P0 as SystemParam>::State, <P1 as SystemParam>::State)

Used to store data which persists across invocations of a system.

type Item<'w, 's> = ParamSet<'w, 's, (P0, P1)>

The item type returned when constructing this system param. The value of this associated type should be Self, instantiated with new lifetimes.

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.

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).

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.

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.

impl<'_w, '_s, P0: SystemParam, P1: SystemParam, P2: SystemParam> SystemParam for ParamSet<'_w, '_s, (P0, P1, P2)>

type State = (<P0 as SystemParam>::State, <P1 as SystemParam>::State, <P2 as SystemParam>::State)

Used to store data which persists across invocations of a system.

type Item<'w, 's> = ParamSet<'w, 's, (P0, P1, P2)>

The item type returned when constructing this system param. The value of this associated type should be Self, instantiated with new lifetimes.

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.

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).

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.

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.

impl<'_w, '_s, P0: SystemParam, P1: SystemParam, P2: SystemParam, P3: SystemParam> SystemParam for ParamSet<'_w, '_s, (P0, P1, P2, P3)>

type State = (<P0 as SystemParam>::State, <P1 as SystemParam>::State, <P2 as SystemParam>::State, <P3 as SystemParam>::State)

Used to store data which persists across invocations of a system.

type Item<'w, 's> = ParamSet<'w, 's, (P0, P1, P2, P3)>

The item type returned when constructing this system param. The value of this associated type should be Self, instantiated with new lifetimes.

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.

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).

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.

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.

impl<'_w, '_s, P0: SystemParam, P1: SystemParam, P2: SystemParam, P3: SystemParam, P4: SystemParam> SystemParam for ParamSet<'_w, '_s, (P0, P1, P2, P3, P4)>

type State = (<P0 as SystemParam>::State, <P1 as SystemParam>::State, <P2 as SystemParam>::State, <P3 as SystemParam>::State, <P4 as SystemParam>::State)

Used to store data which persists across invocations of a system.

type Item<'w, 's> = ParamSet<'w, 's, (P0, P1, P2, P3, P4)>

The item type returned when constructing this system param. The value of this associated type should be Self, instantiated with new lifetimes.

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.

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).

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.

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.

impl<'_w, '_s, P0: SystemParam, P1: SystemParam, P2: SystemParam, P3: SystemParam, P4: SystemParam, P5: SystemParam> SystemParam for ParamSet<'_w, '_s, (P0, P1, P2, P3, P4, P5)>

type State = (<P0 as SystemParam>::State, <P1 as SystemParam>::State, <P2 as SystemParam>::State, <P3 as SystemParam>::State, <P4 as SystemParam>::State, <P5 as SystemParam>::State)

Used to store data which persists across invocations of a system.

type Item<'w, 's> = ParamSet<'w, 's, (P0, P1, P2, P3, P4, P5)>

The item type returned when constructing this system param. The value of this associated type should be Self, instantiated with new lifetimes.

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.

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).

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.

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.

impl<'_w, '_s, P0: SystemParam, P1: SystemParam, P2: SystemParam, P3: SystemParam, P4: SystemParam, P5: SystemParam, P6: SystemParam> SystemParam for ParamSet<'_w, '_s, (P0, P1, P2, P3, P4, P5, P6)>

type State = (<P0 as SystemParam>::State, <P1 as SystemParam>::State, <P2 as SystemParam>::State, <P3 as SystemParam>::State, <P4 as SystemParam>::State, <P5 as SystemParam>::State, <P6 as SystemParam>::State)

Used to store data which persists across invocations of a system.

type Item<'w, 's> = ParamSet<'w, 's, (P0, P1, P2, P3, P4, P5, P6)>

The item type returned when constructing this system param. The value of this associated type should be Self, instantiated with new lifetimes.

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.

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).

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.

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.

impl<'_w, '_s, P0: SystemParam, P1: SystemParam, P2: SystemParam, P3: SystemParam, P4: SystemParam, P5: SystemParam, P6: SystemParam, P7: SystemParam> SystemParam for ParamSet<'_w, '_s, (P0, P1, P2, P3, P4, P5, P6, P7)>

type State = (<P0 as SystemParam>::State, <P1 as SystemParam>::State, <P2 as SystemParam>::State, <P3 as SystemParam>::State, <P4 as SystemParam>::State, <P5 as SystemParam>::State, <P6 as SystemParam>::State, <P7 as SystemParam>::State)

Used to store data which persists across invocations of a system.

type Item<'w, 's> = ParamSet<'w, 's, (P0, P1, P2, P3, P4, P5, P6, P7)>

The item type returned when constructing this system param. The value of this associated type should be Self, instantiated with new lifetimes.

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.

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).

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.

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.

impl<'w, 's, P0> ReadOnlySystemParam for ParamSet<'w, 's, (P0,)>

where P0: ReadOnlySystemParam,

impl<'w, 's, P0, P1> ReadOnlySystemParam for ParamSet<'w, 's, (P0, P1)>

where P0: ReadOnlySystemParam, P1: ReadOnlySystemParam,

impl<'w, 's, P0, P1, P2> ReadOnlySystemParam for ParamSet<'w, 's, (P0, P1, P2)>

where P0: ReadOnlySystemParam, P1: ReadOnlySystemParam, P2: ReadOnlySystemParam,

impl<'w, 's, P0, P1, P2, P3> ReadOnlySystemParam for ParamSet<'w, 's, (P0, P1, P2, P3)>

where P0: ReadOnlySystemParam, P1: ReadOnlySystemParam, P2: ReadOnlySystemParam, P3: ReadOnlySystemParam,

impl<'w, 's, P0, P1, P2, P3, P4> ReadOnlySystemParam for ParamSet<'w, 's, (P0, P1, P2, P3, P4)>

where P0: ReadOnlySystemParam, P1: ReadOnlySystemParam, P2: ReadOnlySystemParam, P3: ReadOnlySystemParam, P4: ReadOnlySystemParam,

impl<'w, 's, P0, P1, P2, P3, P4, P5> ReadOnlySystemParam for ParamSet<'w, 's, (P0, P1, P2, P3, P4, P5)>

where P0: ReadOnlySystemParam, P1: ReadOnlySystemParam, P2: ReadOnlySystemParam, P3: ReadOnlySystemParam, P4: ReadOnlySystemParam, P5: ReadOnlySystemParam,

impl<'w, 's, P0, P1, P2, P3, P4, P5, P6> ReadOnlySystemParam for ParamSet<'w, 's, (P0, P1, P2, P3, P4, P5, P6)>

where P0: ReadOnlySystemParam, P1: ReadOnlySystemParam, P2: ReadOnlySystemParam, P3: ReadOnlySystemParam, P4: ReadOnlySystemParam, P5: ReadOnlySystemParam, P6: ReadOnlySystemParam,

impl<'w, 's, P0, P1, P2, P3, P4, P5, P6, P7> ReadOnlySystemParam for ParamSet<'w, 's, (P0, P1, P2, P3, P4, P5, P6, P7)>

where P0: ReadOnlySystemParam, P1: ReadOnlySystemParam, P2: ReadOnlySystemParam, P3: ReadOnlySystemParam, P4: ReadOnlySystemParam, P5: ReadOnlySystemParam, P6: ReadOnlySystemParam, P7: ReadOnlySystemParam,