Commit graph

2 commits

Author SHA1 Message Date
Joseph
bc8bf34818
Allow disjoint mutable world access via EntityMut (#9419)
# Objective

Fix #4278
Fix #5504
Fix #9422

Provide safe ways to borrow an entire entity, while allowing disjoint
mutable access. `EntityRef` and `EntityMut` are not suitable for this,
since they provide access to the entire world -- they are just helper
types for working with `&World`/`&mut World`.

This has potential uses for reflection and serialization

## Solution

Remove `EntityRef::world`, which allows it to soundly be used within
queries.

`EntityMut` no longer supports structural world mutations, which allows
multiple instances of it to exist for different entities at once.
Structural world mutations are performed using the new type
`EntityWorldMut`.

```rust
fn disjoint_system(
     q2: Query<&mut A>,
     q1: Query<EntityMut, Without<A>>,
) { ... }

let [entity1, entity2] = world.many_entities_mut([id1, id2]);
*entity1.get_mut::<T>().unwrap() = *entity2.get().unwrap();

for entity in world.iter_entities_mut() {
    ...
}
```

---

## Changelog

- Removed `EntityRef::world`, to fix a soundness issue with queries.
+ Removed the ability to structurally mutate the world using
`EntityMut`, which allows it to be used in queries.
+ Added `EntityWorldMut`, which is used to perform structural mutations
that are no longer allowed using `EntityMut`.

## Migration Guide

**Note for maintainers: ensure that the guide for #9604 is updated
accordingly.**

Removed the method `EntityRef::world`, to fix a soundness issue with
queries. If you need access to `&World` while using an `EntityRef`,
consider passing the world as a separate parameter.

`EntityMut` can no longer perform 'structural' world mutations, such as
adding or removing components, or despawning the entity. Additionally,
`EntityMut::world`, `EntityMut::world_mut` , and
`EntityMut::world_scope` have been removed.
Instead, use the newly-added type `EntityWorldMut`, which is a helper
type for working with `&mut World`.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2023-08-28 23:30:59 +00:00
Hennadii Chernyshchyk
fb9a65fa0d
bevy_scene: Add ReflectBundle (#9165)
# Objective

Similar to #6344, but contains only `ReflectBundle` changes. Useful for
scripting. The implementation has also been updated to look exactly like
`ReflectComponent`.

---

## Changelog

### Added

- Reflection for bundles.

---------

Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2023-08-28 16:50:43 +00:00