pub struct StaticSystemParam<'w, 's, P: SystemParam>(/* private fields */);
Expand description

A helper for using system parameters in generic contexts

This type is a SystemParam adapter which always has Self::State::Item == Self (ignoring lifetimes for brevity), no matter the argument SystemParam (P) (other than that P must be 'static)

This makes it useful for having arbitrary SystemParam type arguments to function systems, or for generic types using the SystemParam derive:

use bevy_ecs::system::{SystemParam, StaticSystemParam};
#[derive(SystemParam)]
struct GenericParam<'w,'s, T: SystemParam + 'static> {
    field: StaticSystemParam<'w, 's, T>,
}
fn do_thing_generically<T: SystemParam + 'static>(t: StaticSystemParam<T>) {}

fn check_always_is_system<T: SystemParam + 'static>(){
    bevy_ecs::system::assert_is_system(do_thing_generically::<T>);
}

Note that in a real case you’d generally want additional bounds on P, for your use of the parameter to have a reason to be generic.

For example, using this would allow a type to be generic over whether a resource is accessed mutably or not, with impls being bounded on P: Deref<Target=MyType>, and P: DerefMut<Target=MyType> depending on whether the method requires mutable access or not.

The method which doesn’t use this type will not compile:


fn do_thing_generically<T: SystemParam + 'static>(t: T) {}

#[derive(SystemParam)]
struct GenericParam<'w, 's, T: SystemParam> {
    field: T,
    // Use the lifetimes in this type, or they will be unbound.
    phantom: core::marker::PhantomData<&'w &'s ()>
}

Implementations§

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impl<'w, 's, P: SystemParam> StaticSystemParam<'w, 's, P>

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pub fn into_inner(self) -> SystemParamItem<'w, 's, P>

Get the value of the parameter

Trait Implementations§

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impl<'w, 's, P: SystemParam> Deref for StaticSystemParam<'w, 's, P>

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type Target = <P as SystemParam>::Item<'w, 's>

The resulting type after dereferencing.
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fn deref(&self) -> &Self::Target

Dereferences the value.
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impl<'w, 's, P: SystemParam> DerefMut for StaticSystemParam<'w, 's, P>

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fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.
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impl<P: SystemParam + 'static> SystemParam for StaticSystemParam<'_, '_, P>

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type State = <P as SystemParam>::State

Used to store data which persists across invocations of a system.
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type Item<'world, 'state> = StaticSystemParam<'world, 'state, P>

The item type returned when constructing this system param. The value of this associated type should be Self, instantiated with new lifetimes. Read more
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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.
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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).
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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.
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unsafe fn get_param<'world, 'state>( state: &'state mut Self::State, system_meta: &SystemMeta, world: UnsafeWorldCell<'world>, change_tick: Tick ) -> Self::Item<'world, 'state>

Creates a parameter to be passed into a SystemParamFunction. Read more
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impl<'w, 's, P: ReadOnlySystemParam + 'static> ReadOnlySystemParam for StaticSystemParam<'w, 's, P>

Auto Trait Implementations§

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impl<'w, 's, P> RefUnwindSafe for StaticSystemParam<'w, 's, P>
where <P as SystemParam>::Item<'w, 's>: RefUnwindSafe,

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impl<'w, 's, P> Send for StaticSystemParam<'w, 's, P>
where <P as SystemParam>::Item<'w, 's>: Send,

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impl<'w, 's, P> Sync for StaticSystemParam<'w, 's, P>
where <P as SystemParam>::Item<'w, 's>: Sync,

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impl<'w, 's, P> Unpin for StaticSystemParam<'w, 's, P>
where <P as SystemParam>::Item<'w, 's>: Unpin,

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impl<'w, 's, P> UnwindSafe for StaticSystemParam<'w, 's, P>
where <P as SystemParam>::Item<'w, 's>: UnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> Downcast for T
where T: Any,

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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.
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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.
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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.
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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.
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impl<T> DowncastSync for T
where T: Any + Send + Sync,

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fn into_any_arc(self: Arc<T>) -> Arc<dyn Any + Send + Sync>

Convert Arc<Trait> (where Trait: Downcast) to Arc<Any>. Arc<Any> can then be further downcast into Arc<ConcreteType> where ConcreteType implements Trait.
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more