flax 0.7.1

An ergonomic archetypical ECS
Documentation 
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use flax::{
    buffer::ComponentBuffer,
    error::MissingComponent,
    metadata::Metadata,
    vtable::{ComponentVTable, LazyComponentBuffer},
    *,
};
use glam::{vec2, Vec2};

#[test]
fn custom_component() {
    let mut world = World::new();

    static VTABLE: ComponentVTable<Vec2> = ComponentVTable::new(
        "position",
        LazyComponentBuffer::new(|desc| {
            let mut buf = ComponentBuffer::new();
            <Debuggable as Metadata<Vec2>>::attach(desc, &mut buf);
            buf
        }),
    );

    let position = world.spawn_component(&VTABLE);

    let id = Entity::builder()
        .set(position, vec2(1.0, 6.4))
        .spawn(&mut world);

    assert_eq!(world.get(id, position).as_deref(), Ok(&vec2(1.0, 6.4)));

    // When `position` is despawned, it is removed from all entities.
    // This ensured that dead components never exist
    world.despawn(position.id()).unwrap();

    assert_eq!(
        world.get(id, position).as_deref(),
        Err(&Error::MissingComponent(MissingComponent {
            id,
            desc: position.desc()
        })),
    );
}