Add `World::entity_scope` to split the borrow on the `World` by extracting a single entity about bevy HOT 3 OPEN

Returning an actual &mut World would be unsound even with any form of entity disabling, as it still allows you to do structural changes that might affect the disabled entity. And there's also the extreme case where the World is replaced (i.e. by doing *world = World::new();)

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An approach similar to EntityWorldMut::take + EntityWorldMut::insert could work, but I don't see a way to optimize it to avoid the archetype move, which is pretty costly.

from bevy.

Returning an actual &mut World would be unsound even with any form of entity disabling

how about instead of having access to the whole entity (EntityMut) - you just get access to a set of components?

let _ = world.entity_mut(entity).component_scope::<(Position, Health), _>(|world, (p, h)| {
   // blabla
}).unwrap(); // panics if either Position or Health doesn't exist

this can almost be done already with EntityWorldMut::take + EntityWorldMut::insert but it triggers Added (bad) and it's surprisingly easy to gorget to insert the component back afterwards.

from bevy.