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"with_children" does not support adding single component #277
Description
Currently, the implementation requires that the component being spawned implemented DynamicBundle, so you can't do something like this:
fn setup(
mut commands: Commands,
) {
commands
// Player
.spawn(SpriteComponents {
material: materials.add(Color::rgb(0.5, 0.0, 0.0).into()),
translation: Translation(Vec3::new(window_desc.width as f32 / 2.0, 50.0, 0.0)),
sprite: Sprite {
size: Vec2::new(30.0, 30.0),
},
..Default::default()
})
.with(Player::new())
.with_children(|parent| {
parent.spawn(BulletEmitter::new());
});
}Instead, you need to do it that way:
.with_children(|parent| {
parent.spawn( (BulletEmitter::new(), ) );
});
}While this is a decent workaround, could it be possible to make it so you can use a regular Component too?
A friend suggested implementing the following, although I'm not knowledgeable about Rust enough to do so myself:
DynamicBundle for T: Component
Thanks!
Activity
Ratysz commentedon Aug 22, 2020
This will run into duplicate implementation, partially because we don't have trait specialization (yet, potentially ever).
T: Componentbound means everything that can be a component - including all the tuples thatDynamicBundleis implemented for elsewhere.It can be circumvented with a "marker" generic parameter in
DynamicBundletrait, but this could pollute all APIs that useDynamicBundleand potentiallyBundlewith that rather confusing parameter. I'm almost certain it won't come up in normal use of the public API, but it would show up in documentation.ryo33 commentedon Sep 30, 2020
I thought about
.with_child(BulletEmitter::new()), which wraps the currentwith_children, but it's too specific.In that case, I prefer to;
BulletEmitterComponents.to_bundle(self)forBulletEmitterif it seems never used with other components.alice-i-cecile commentedon Apr 3, 2021
This should be solved with the new Commands API in 0.5. See #1703.
alice-i-cecile commentedon Apr 16, 2021
Fixed in 0.5