Struct hecs::EntityRef

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pub struct EntityRef<'a> { /* private fields */ }

Expand description

Handle to an entity with any component types

Implementations§

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impl<'a> EntityRef<'a>

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pub fn entity(&self) -> Entity

Get the Entity handle associated with this entity

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pub fn satisfies<Q: Query>(&self) -> bool

Determine whether this entity would satisfy the query Q without borrowing any components

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pub fn has<T: Component>(&self) -> bool

Determine whether this entity has a T component without borrowing it

Equivalent to satisfies::<&T>

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pub fn get<T: ComponentRef<'a>>(&self) -> Option<T::Ref>

Borrow a single component, if it exists

T must be a shared or unique reference to a component type.

§Example

let mut world = World::new();
let a = world.spawn((42, "abc"));
let e = world.entity(a).unwrap();
*e.get::<&mut i32>().unwrap() = 17;
assert_eq!(*e.get::<&i32>().unwrap(), 17);

Panics if T is a unique reference and the component is already borrowed, or if the component is already uniquely borrowed.

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pub fn query<Q: Query>(&self) -> QueryOne<'a, Q>

Run a query against this entity

Equivalent to invoking World::query_one on the entity. May outlive self.

§Example

let mut world = World::new();
let a = world.spawn((123, true, "abc"));
// The returned query must outlive the borrow made by `get`
let mut query = world.entity(a).unwrap().query::<(&mut i32, &bool)>();
let (number, flag) = query.get().unwrap();
if *flag { *number *= 2; }
assert_eq!(*number, 246);

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pub fn component_types(&self) -> impl Iterator<Item = TypeId> + 'a

Enumerate the types of the entity’s components

Convenient for dispatching component-specific logic for a single entity. For example, this can be combined with a HashMap<TypeId, Box<dyn Handler>> where Handler is some user-defined trait with methods for serialization, or to be called after spawning or before despawning to maintain secondary indices.

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