# Objective
- Contributes to #15460
## Solution
- Added the following features:
- `std` (default)
- `async_executor` (default)
- `edge_executor`
- `critical-section`
- `portable-atomic`
- Gated `tracing` in `bevy_utils` to allow compilation on certain
platforms
- Switched from `tracing` to `log` for simple message logging within
`bevy_ecs`. Note that `tracing` supports capturing from `log` so this
should be an uncontroversial change.
- Fixed imports and added feature gates as required
- Made `bevy_tasks` optional within `bevy_ecs`. Turns out it's only
needed for parallel operations which are already gated behind
`multi_threaded` anyway.
## Testing
- Added to `compile-check-no-std` CI command
- `cargo check -p bevy_ecs --no-default-features --features
edge_executor,critical-section,portable-atomic --target
thumbv6m-none-eabi`
- `cargo check -p bevy_ecs --no-default-features --features
edge_executor,critical-section`
- `cargo check -p bevy_ecs --no-default-features`
## Draft Release Notes
Bevy's core ECS now supports `no_std` platforms.
In prior versions of Bevy, it was not possible to work with embedded or
niche platforms due to our reliance on the standard library, `std`. This
has blocked a number of novel use-cases for Bevy, such as an embedded
database for IoT devices, or for creating games on retro consoles.
With this release, `bevy_ecs` no longer requires `std`. To use Bevy on a
`no_std` platform, you must disable default features and enable the new
`edge_executor` and `critical-section` features. You may also need to
enable `portable-atomic` and `critical-section` if your platform does
not natively support all atomic types and operations used by Bevy.
```toml
[dependencies]
bevy_ecs = { version = "0.16", default-features = false, features = [
# Required for platforms with incomplete atomics (e.g., Raspberry Pi Pico)
"portable-atomic",
"critical-section",
# Optional
"bevy_reflect",
"serialize",
"bevy_debug_stepping",
"edge_executor"
] }
```
Currently, this has been tested on bare-metal x86 and the Raspberry Pi
Pico. If you have trouble using `bevy_ecs` on a particular platform,
please reach out either through a GitHub issue or in the `no_std`
working group on the Bevy Discord server.
Keep an eye out for future `no_std` updates as we continue to improve
the parity between `std` and `no_std`. We look forward to seeing what
kinds of applications are now possible with Bevy!
## Notes
- Creating PR in draft to ensure CI is passing before requesting
reviews.
- This implementation has no support for multithreading in `no_std`,
especially due to `NonSend` being unsound if allowed in multithreading.
The reason is we cannot check the `ThreadId` in `no_std`, so we have no
mechanism to at-runtime determine if access is sound.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Vic <59878206+Victoronz@users.noreply.github.com>
# Objective
Example error message beforehand:
```
error[B0001]: Query<&mut Data, ()> in system bevytest::main::{{closure}} accesses component(s)Data in a way that conflicts with a previous…
```
# Objective
Expand `track_change_detection` feature to also track entity spawns and
despawns. Use this to create better error messages.
# Solution
Adds `Entities::entity_get_spawned_or_despawned_by` as well as `{all
entity reference types}::spawned_by`.
This also removes the deprecated `get_many_entities_mut` & co (and
therefore can't land in 0.15) because we don't yet have no Polonius.
## Testing
Added a test that checks that the locations get updated and these
updates are ordered correctly vs hooks & observers.
---
## Showcase
Access location:
```rust
let mut world = World::new();
let entity = world.spawn_empty().id();
println!("spawned by: {}", world.entity(entity).spawned_by());
```
```
spawned by: src/main.rs:5:24
```
Error message (with `track_change_detection`):
```rust
world.despawn(entity);
world.entity(entity);
```
```
thread 'main' panicked at src/main.rs:11:11:
Entity 0v1#4294967296 was despawned by src/main.rs:10:11
```
and without:
```
thread 'main' panicked at src/main.rs:11:11:
Entity 0v1#4294967296 does not exist (enable `track_change_detection` feature for more details)
```
Similar error messages now also exists for `Query::get`,
`World::entity_mut`, `EntityCommands` creation and everything that
causes `B0003`, e.g.
```
error[B0003]: Could not insert a bundle (of type `MaterialMeshBundle<StandardMaterial>`) for entity Entity { index: 7, generation: 1 }, which was despawned by src/main.rs:10:11. See: https://bevyengine.org/learn/errors/#b0003
```
---------
Co-authored-by: kurk070ff <108901106+kurk070ff@users.noreply.github.com>
Co-authored-by: Freya Pines <freya@MacBookAir.lan>
Co-authored-by: Freya Pines <freya@Freyas-MacBook-Air.local>
Co-authored-by: Matty Weatherley <weatherleymatthew@gmail.com>
## Objective
Thanks to @eugineerd's work on entity cloning (#16132), we now have a
robust way to copy components between entities. We can extend this to
implement some useful functionality that would have been more
complicated before.
Closes#15350.
## Solution
`EntityCloneBuilder` now automatically includes required components
alongside any component added/removed from the component filter.
Added the following methods to `EntityCloneBuilder`:
- `move_components`
- `without_required_components`
Added the following methods to `EntityWorldMut` and `EntityCommands`:
- `clone_with`
- `clone_components`
- `move_components`
Also added `clone_and_spawn` and `clone_and_spawn_with` to
`EntityWorldMut` (`EntityCommands` already had them).
## Showcase
```
assert_eq!(world.entity(entity_a).get::<B>(), Some(&B));
assert_eq!(world.entity(entity_b).get::<B>(), None);
world.entity_mut(entity_a).clone_components::<B>(entity_b);
assert_eq!(world.entity(entity_a).get::<B>(), Some(&B));
assert_eq!(world.entity(entity_b).get::<B>(), Some(&B));
assert_eq!(world.entity(entity_a).get::<C>(), Some(&C(5)));
assert_eq!(world.entity(entity_b).get::<C>(), None);
world.entity_mut(entity_a).move_components::<C>(entity_b);
assert_eq!(world.entity(entity_a).get::<C>(), None);
assert_eq!(world.entity(entity_b).get::<C>(), Some(&C(5)));
```
# Objective
- Writing an API, and I want to allow users to pass in extra data
alongside the API provided input, and tuples are the most natural
extension in this case.
- Bring `SystemInput` up to par with `SystemParam` for tuple support.
## Solution
- Added impls for tuples up to 8 elements. If you need a 9-arity tuple
or more, write your own `SystemInput` type (it's incredibly simple to
do).
## Testing
- Added a test demonstrating this.
---
## Showcase
Tuples of arbitrary`SystemInput`s are now supported:
```rust
fn by_value((In(a), In(b)): (In<usize>, In<usize>)) -> usize {
a + b
}
fn by_mut((InMut(a), In(b)): (InMut<usize>, In<usize>)) {
*a += b;
}
let mut world = World::new();
let mut by_value = IntoSystem::into_system(by_value);
let mut by_mut = IntoSystem::into_system(by_mut);
by_value.initialize(&mut world);
by_mut.initialize(&mut world);
assert_eq!(by_value.run((12, 24), &mut world), 36);
let mut a = 10;
let b = 5;
by_mut.run((&mut a, b), &mut world);
assert_eq!(*a, 15);
```
# Objective
Fixes#16776
## Solution
- reflect `&'static Location` as an opaque type
- I've added this to `impls/std.rs` because other core types are there
too. Maybe they should be split out into a `core.rs` in another PR.
- add source location to `EventId` (behind the
`tracking_change_detection` feature flag)
## Testing
---
## Showcase
```rust
fn apply_damage_to_health(
mut dmg_events: EventReader<DealDamage>,
) {
for (event, event_id) in dmg_events.read_with_id() {
info!(
"Applying {} damage, triggered by {}",
event.amount, event_id.caller
);
…
```
```
2024-12-12T01:21:50.126827Z INFO event: Applying 9 damage, triggered by examples/ecs/event.rs:47:16
```
## Migration Guide
- If you manually construct a `SendEvent`, use `SendEvent::new()`
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
- Fixes#16497
- This is my first PR, so I'm still learning to contribute to the
project
## Solution
- Added struct `UnregisterSystemCached` and function
`unregister_system_cached`
- renamed `World::run_system_with_input` to `run_system_with`
- reordered input parameters for `World::run_system_once_with`
## Testing
- Added a crude test which registers a system via
`World::register_system_cached`, and removes it via
`Command::unregister_system_cached`.
## Migration Guide
- Change all occurrences of `World::run_system_with_input` to
`World::run_system_with`.
- swap the order of input parameters for `World::run_system_once_with`
such that the system comes before the input.
---------
Co-authored-by: Paul Mattern <mail@paulmattern.dev>
## Objective
Follow-up to #16672.
`EntityCommands::clone` looks the same as the `Clone` trait, which could
be confusing. A discord discussion has made me realize that's probably a
bigger problem than I thought. Oops :P
## Solution
Renamed `EntityCommands::clone` to `EntityCommands::clone_and_spawn`,
renamed `EntityCommands::clone_with` to
`EntityCommands::clone_and_spawn_with`. Also added some docs explaining
the commands' relation to `Clone` (components need to implement it (or
`Reflect`)).
## Showcase
```
// Create a new entity and keep its EntityCommands
let mut entity = commands.spawn((ComponentA(10), ComponentB(20)));
// Create a clone of the first entity
let mut entity_clone = entity.clone_and_spawn();
```
## The Bikeshed
- `clone_and_spawn` (Alice's suggestion)
- `spawn_clone` (benfrankel's suggestion)
- `spawn_cloned` (rparrett's suggestion)
# Objective
The documentation for `Query::transmute_lens` lists some allowed
transmutes, but the list is incomplete.
## Solution
Document the underlying rules for what transmutes are allowed.
Add a longer list of examples. Write them as doc tests to ensure that
those examples are actually allowed.
I'm assuming that anything that can be done today is intended to be
supported! If any of these examples are things we plan to prohibit in
the future then we can add some warnings to that effect.
# Objective
- Remove `derive_more`'s error derivation and replace it with
`thiserror`
## Solution
- Added `derive_more`'s `error` feature to `deny.toml` to prevent it
sneaking back in.
- Reverted to `thiserror` error derivation
## Notes
Merge conflicts were too numerous to revert the individual changes, so
this reversion was done manually. Please scrutinise carefully during
review.
## Objective
I was resolving a conflict between #16132 and my PR #15929 and thought
the `clone_entity` commands made more sense in `EntityCommands`.
## Solution
Moved `Commands::clone_entity` to `EntityCommands::clone`, moved
`Commands::clone_entity_with` to `EntityCommands::clone_with`.
## Testing
Ran the two tests that used the old methods.
## Showcase
```
// Create a new entity and keep its EntityCommands.
let mut entity = commands.spawn((ComponentA(10), ComponentB(20)));
// Create a clone of the first entity
let mut entity_clone = entity.clone();
```
The only potential downside is that the method name is now the same as
the one from the `Clone` trait. `EntityCommands` doesn't implement
`Clone` though, so there's no actual conflict.
Maybe I'm biased because this'll work better with my PR, but I think the
UX is nicer regardless.
# Objective
Error handling in bevy is hard. See for reference
https://github.com/bevyengine/bevy/issues/11562,
https://github.com/bevyengine/bevy/issues/10874 and
https://github.com/bevyengine/bevy/issues/12660. The goal of this PR is
to make it better, by allowing users to optionally return `Result` from
systems as outlined by Cart in
<https://github.com/bevyengine/bevy/issues/14275#issuecomment-2223708314>.
## Solution
This PR introduces a new `ScheuleSystem` type to represent systems that
can be added to schedules. Instances of this type contain either an
infallible `BoxedSystem<(), ()>` or a fallible `BoxedSystem<(),
Result>`. `ScheuleSystem` implements `System<In = (), Out = Result>` and
replaces all uses of `BoxedSystem` in schedules. The async executor now
receives a result after executing a system, which for infallible systems
is always `Ok(())`. Currently it ignores this result, but more useful
error handling could also be implemented.
Aliases for `Error` and `Result` have been added to the `bevy_ecs`
prelude, as well as const `OK` which new users may find more friendly
than `Ok(())`.
## Testing
- Currently there are not actual semantics changes that really require
new tests, but I added a basic one just to make sure we don't break
stuff in the future.
- The behavior of existing systems is totally unchanged, including
logging.
- All of the existing systems tests pass, and I have not noticed
anything strange while playing with the examples
## Showcase
The following minimal example prints "hello world" once, then completes.
```rust
use bevy::prelude::*;
fn main() {
App::new().add_systems(Update, hello_world_system).run();
}
fn hello_world_system() -> Result {
println!("hello world");
Err("string")?;
println!("goodbye world");
OK
}
```
## Migration Guide
This change should be pretty much non-breaking, except for users who
have implemented their own custom executors. Those users should use
`ScheduleSystem` in place of `BoxedSystem<(), ()>` and import the
`System` trait where needed. They can choose to do whatever they wish
with the result.
## Current Work
+ [x] Fix tests & doc comments
+ [x] Write more tests
+ [x] Add examples
+ [X] Draft release notes
## Draft Release Notes
As of this release, systems can now return results.
First a bit of background: Bevy has hisotrically expected systems to
return the empty type `()`. While this makes sense in the context of the
ecs, it's at odds with how error handling is typically done in rust:
returning `Result::Error` to indicate failure, and using the
short-circuiting `?` operator to propagate that error up the call stack
to where it can be properly handled. Users of functional languages will
tell you this is called "monadic error handling".
Not being able to return `Results` from systems left bevy users with a
quandry. They could add custom error handling logic to every system, or
manually pipe every system into an error handler, or perhaps sidestep
the issue with some combination of fallible assignents, logging, macros,
and early returns. Often, users would just litter their systems with
unwraps and possible panics.
While any one of these approaches might be fine for a particular user,
each of them has their own drawbacks, and none makes good use of the
language. Serious issues could also arrise when two different crates
used by the same project made different choices about error handling.
Now, by returning results, systems can defer error handling to the
application itself. It looks like this:
```rust
// Previous, handling internally
app.add_systems(my_system)
fn my_system(window: Query<&Window>) {
let Ok(window) = query.get_single() else {
return;
};
// ... do something to the window here
}
// Previous, handling externally
app.add_systems(my_system.pipe(my_error_handler))
fn my_system(window: Query<&Window>) -> Result<(), impl Error> {
let window = query.get_single()?;
// ... do something to the window here
Ok(())
}
// Previous, panicking
app.add_systems(my_system)
fn my_system(window: Query<&Window>) {
let window = query.single();
// ... do something to the window here
}
// Now
app.add_systems(my_system)
fn my_system(window: Query<&Window>) -> Result {
let window = query.get_single()?;
// ... do something to the window here
Ok(())
}
```
There are currently some limitations. Systems must either return `()` or
`Result<(), Box<dyn Error + Send + Sync + 'static>>`, with no
in-between. Results are also ignored by default, and though implementing
a custom handler is possible, it involves writing your own custom ecs
executor (which is *not* recomended).
Systems should return errors when they cannot perform their normal
behavior. In turn, errors returned to the executor while running the
schedule will (eventually) be treated as unexpected. Users and library
authors should prefer to return errors for anything that disrupts the
normal expected behavior of a system, and should only handle expected
cases internally.
We have big plans for improving error handling further:
+ Allowing users to change the error handling logic of the default
executors.
+ Adding source tracking and optional backtraces to errors.
+ Possibly adding tracing-levels (Error/Warn/Info/Debug/Trace) to
errors.
+ Generally making the default error logging more helpful and
inteligent.
+ Adding monadic system combininators for fallible systems.
+ Possibly removing all panicking variants from our api.
---------
Co-authored-by: Zachary Harrold <zac@harrold.com.au>
# Objective
- Required by #16622 due to differing implementations of `System` by
`FunctionSystem` and `ExclusiveFunctionSystem`.
- Optimize the memory usage of instances of `apply_deferred` in system
schedules.
## Solution
By changing `apply_deferred` from being an ordinary system that ends up
as an `ExclusiveFunctionSystem`, and instead into a ZST struct that
implements `System` manually, we save ~320 bytes per instance of
`apply_deferred` in any schedule.
## Testing
- All current tests pass.
---
## Migration Guide
- If you were previously calling the special `apply_deferred` system via
`apply_deferred(world)`, don't.
# Objective
Outside of the `bevy_ecs` crate it's hard to implement `SystemParam`
trait on params that require access to the `World`, because `init_state`
expects user to extend access in `SystemMeta` and access-related fields
of `SystemMeta` are private.
## Solution
Expose those fields as a functions
# Objective
- Fixes#16208
## Solution
- Added an associated type to `Component`, `Mutability`, which flags
whether a component is mutable, or immutable. If `Mutability= Mutable`,
the component is mutable. If `Mutability= Immutable`, the component is
immutable.
- Updated `derive_component` to default to mutable unless an
`#[component(immutable)]` attribute is added.
- Updated `ReflectComponent` to check if a component is mutable and, if
not, panic when attempting to mutate.
## Testing
- CI
- `immutable_components` example.
---
## Showcase
Users can now mark a component as `#[component(immutable)]` to prevent
safe mutation of a component while it is attached to an entity:
```rust
#[derive(Component)]
#[component(immutable)]
struct Foo {
// ...
}
```
This prevents creating an exclusive reference to the component while it
is attached to an entity. This is particularly powerful when combined
with component hooks, as you can now fully track a component's value,
ensuring whatever invariants you desire are upheld. Before this would be
done my making a component private, and manually creating a `QueryData`
implementation which only permitted read access.
<details>
<summary>Using immutable components as an index</summary>
```rust
/// This is an example of a component like [`Name`](bevy::prelude::Name), but immutable.
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Component)]
#[component(
immutable,
on_insert = on_insert_name,
on_replace = on_replace_name,
)]
pub struct Name(pub &'static str);
/// This index allows for O(1) lookups of an [`Entity`] by its [`Name`].
#[derive(Resource, Default)]
struct NameIndex {
name_to_entity: HashMap<Name, Entity>,
}
impl NameIndex {
fn get_entity(&self, name: &'static str) -> Option<Entity> {
self.name_to_entity.get(&Name(name)).copied()
}
}
fn on_insert_name(mut world: DeferredWorld<'_>, entity: Entity, _component: ComponentId) {
let Some(&name) = world.entity(entity).get::<Name>() else {
unreachable!()
};
let Some(mut index) = world.get_resource_mut::<NameIndex>() else {
return;
};
index.name_to_entity.insert(name, entity);
}
fn on_replace_name(mut world: DeferredWorld<'_>, entity: Entity, _component: ComponentId) {
let Some(&name) = world.entity(entity).get::<Name>() else {
unreachable!()
};
let Some(mut index) = world.get_resource_mut::<NameIndex>() else {
return;
};
index.name_to_entity.remove(&name);
}
// Setup our name index
world.init_resource::<NameIndex>();
// Spawn some entities!
let alyssa = world.spawn(Name("Alyssa")).id();
let javier = world.spawn(Name("Javier")).id();
// Check our index
let index = world.resource::<NameIndex>();
assert_eq!(index.get_entity("Alyssa"), Some(alyssa));
assert_eq!(index.get_entity("Javier"), Some(javier));
// Changing the name of an entity is also fully capture by our index
world.entity_mut(javier).insert(Name("Steven"));
// Javier changed their name to Steven
let steven = javier;
// Check our index
let index = world.resource::<NameIndex>();
assert_eq!(index.get_entity("Javier"), None);
assert_eq!(index.get_entity("Steven"), Some(steven));
```
</details>
Additionally, users can use `Component<Mutability = ...>` in trait
bounds to enforce that a component _is_ mutable or _is_ immutable. When
using `Component` as a trait bound without specifying `Mutability`, any
component is applicable. However, methods which only work on mutable or
immutable components are unavailable, since the compiler must be
pessimistic about the type.
## Migration Guide
- When implementing `Component` manually, you must now provide a type
for `Mutability`. The type `Mutable` provides equivalent behaviour to
earlier versions of `Component`:
```rust
impl Component for Foo {
type Mutability = Mutable;
// ...
}
```
- When working with generic components, you may need to specify that
your generic parameter implements `Component<Mutability = Mutable>`
rather than `Component` if you require mutable access to said component.
- The entity entry API has had to have some changes made to minimise
friction when working with immutable components. Methods which
previously returned a `Mut<T>` will now typically return an
`OccupiedEntry<T>` instead, requiring you to add an `into_mut()` to get
the `Mut<T>` item again.
## Draft Release Notes
Components can now be made immutable while stored within the ECS.
Components are the fundamental unit of data within an ECS, and Bevy
provides a number of ways to work with them that align with Rust's rules
around ownership and borrowing. One part of this is hooks, which allow
for defining custom behavior at key points in a component's lifecycle,
such as addition and removal. However, there is currently no way to
respond to _mutation_ of a component using hooks. The reasons for this
are quite technical, but to summarize, their addition poses a
significant challenge to Bevy's core promises around performance.
Without mutation hooks, it's relatively trivial to modify a component in
such a way that breaks invariants it intends to uphold. For example, you
can use `core::mem::swap` to swap the components of two entities,
bypassing the insertion and removal hooks.
This means the only way to react to this modification is via change
detection in a system, which then begs the question of what happens
_between_ that alteration and the next run of that system?
Alternatively, you could make your component private to prevent
mutation, but now you need to provide commands and a custom `QueryData`
implementation to allow users to interact with your component at all.
Immutable components solve this problem by preventing the creation of an
exclusive reference to the component entirely. Without an exclusive
reference, the only way to modify an immutable component is via removal
or replacement, which is fully captured by component hooks. To make a
component immutable, simply add `#[component(immutable)]`:
```rust
#[derive(Component)]
#[component(immutable)]
struct Foo {
// ...
}
```
When implementing `Component` manually, there is an associated type
`Mutability` which controls this behavior:
```rust
impl Component for Foo {
type Mutability = Mutable;
// ...
}
```
Note that this means when working with generic components, you may need
to specify that a component is mutable to gain access to certain
methods:
```rust
// Before
fn bar<C: Component>() {
// ...
}
// After
fn bar<C: Component<Mutability = Mutable>>() {
// ...
}
```
With this new tool, creating index components, or caching data on an
entity should be more user friendly, allowing libraries to provide APIs
relying on components and hooks to uphold their invariants.
## Notes
- ~~I've done my best to implement this feature, but I'm not happy with
how reflection has turned out. If any reflection SMEs know a way to
improve this situation I'd greatly appreciate it.~~ There is an
outstanding issue around the fallibility of mutable methods on
`ReflectComponent`, but the DX is largely unchanged from `main` now.
- I've attempted to prevent all safe mutable access to a component that
does not implement `Component<Mutability = Mutable>`, but there may
still be some methods I have missed. Please indicate so and I will
address them, as they are bugs.
- Unsafe is an escape hatch I am _not_ attempting to prevent. Whatever
you do with unsafe is between you and your compiler.
- I am marking this PR as ready, but I suspect it will undergo fairly
major revisions based on SME feedback.
- I've marked this PR as _Uncontroversial_ based on the feature, not the
implementation.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Benjamin Brienen <benjamin.brienen@outlook.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
Co-authored-by: Nuutti Kotivuori <naked@iki.fi>
# Objective
Make documentation of a component's required components more visible by
moving it to the type's docs
## Solution
Change `#[require]` from a derive macro helper to an attribute macro.
Disadvantages:
- this silences any unused code warnings on the component, as it is used
by the macro!
- need to import `require` if not using the ecs prelude (I have not
included this in the migration guilde as Rust tooling already suggests
the fix)
---
## Showcase
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: JMS55 <47158642+JMS55@users.noreply.github.com>
# Objective
Fixes#15941
## Solution
Created https://crates.io/crates/variadics_please and moved the code
there; updating references
`bevy_utils/macros` is deleted.
## Testing
cargo check
## Migration Guide
Use `variadics_please::{all_tuples, all_tuples_with_size}` instead of
`bevy::utils::{all_tuples, all_tuples_with_size}`.
## Objective
Fixes#1515
This PR implements a flexible entity cloning system. The primary use
case for it is to clone dynamically-generated entities.
Example:
```rs
#[derive(Component, Clone)]
pub struct Projectile;
#[derive(Component, Clone)]
pub struct Damage {
value: f32,
}
fn player_input(
mut commands: Commands,
projectiles: Query<Entity, With<Projectile>>,
input: Res<ButtonInput<KeyCode>>,
) {
// Fire a projectile
if input.just_pressed(KeyCode::KeyF) {
commands.spawn((Projectile, Damage { value: 10.0 }));
}
// Triplicate all active projectiles
if input.just_pressed(KeyCode::KeyT) {
for projectile in projectiles.iter() {
// To triplicate a projectile we need to create 2 more clones
for _ in 0..2{
commands.clone_entity(projectile)
}
}
}
}
```
## Solution
### Commands
Add a `clone_entity` command to create a clone of an entity with all
components that can be cloned. Components that can't be cloned will be
ignored.
```rs
commands.clone_entity(entity)
```
If there is a need to configure the cloning process (like set to clone
recursively), there is a second command:
```rs
commands.clone_entity_with(entity, |builder| {
builder.recursive(true)
});
```
Both of these commands return `EntityCommands` of the cloned entity, so
the copy can be modified afterwards.
### Builder
All these commands use `EntityCloneBuilder` internally. If there is a
need to clone an entity using `World` instead, it is also possible:
```rs
let entity = world.spawn(Component).id();
let entity_clone = world.spawn_empty().id();
EntityCloneBuilder::new(&mut world).clone_entity(entity, entity_clone);
```
Builder has methods to `allow` or `deny` certain components during
cloning if required and can be extended by implementing traits on it.
This PR includes two `EntityCloneBuilder` extensions:
`CloneEntityWithObserversExt` to configure adding cloned entity to
observers of the original entity, and `CloneEntityRecursiveExt` to
configure cloning an entity recursively.
### Clone implementations
By default, all components that implement either `Clone` or `Reflect`
will be cloned (with `Clone`-based implementation preferred in case
component implements both).
This can be overriden on a per-component basis:
```rs
impl Component for SomeComponent {
const STORAGE_TYPE: StorageType = StorageType::Table;
fn get_component_clone_handler() -> ComponentCloneHandler {
// Don't clone this component
ComponentCloneHandler::Ignore
}
}
```
### `ComponentCloneHandlers`
Clone implementation specified in `get_component_clone_handler` will get
registered in `ComponentCloneHandlers` (stored in
`bevy_ecs::component::Components`) at component registration time.
The clone handler implementation provided by a component can be
overriden after registration like so:
```rs
let component_id = world.components().component_id::<Component>().unwrap()
world.get_component_clone_handlers_mut()
.set_component_handler(component_id, ComponentCloneHandler::Custom(component_clone_custom))
```
The default clone handler for all components that do not explicitly
define one (or don't derive `Component`) is
`component_clone_via_reflect` if `bevy_reflect` feature is enabled, and
`component_clone_ignore` (noop) otherwise.
Default handler can be overriden using
`ComponentCloneHandlers::set_default_handler`
### Handlers
Component clone handlers can be used to modify component cloning
behavior. The general signature for a handler that can be used in
`ComponentCloneHandler::Custom` is as follows:
```rs
pub fn component_clone_custom(
world: &mut DeferredWorld,
entity_cloner: &EntityCloner,
) {
// implementation
}
```
The `EntityCloner` implementation (used internally by
`EntityCloneBuilder`) assumes that after calling this custom handler,
the `target` entity has the desired version of the component from the
`source` entity.
### Builder handler overrides
Besides component-defined and world-overriden handlers,
`EntityCloneBuilder` also has a way to override handlers locally. It is
mainly used to allow configuration methods like `recursive` and
`add_observers`.
```rs
// From observer clone handler implementation
impl CloneEntityWithObserversExt for EntityCloneBuilder<'_> {
fn add_observers(&mut self, add_observers: bool) -> &mut Self {
if add_observers {
self.override_component_clone_handler::<ObservedBy>(ComponentCloneHandler::Custom(
component_clone_observed_by,
))
} else {
self.remove_component_clone_handler_override::<ObservedBy>()
}
}
}
```
## Testing
Includes some basic functionality tests and doctests.
Performance-wise this feature is the same as calling `clone` followed by
`insert` for every entity component. There is also some inherent
overhead due to every component clone handler having to access component
data through `World`, but this can be reduced without breaking current
public API in a later PR.
# Objective
Combine the `Option<_>` state in `FunctionSystem` into a single `Option`
to provide clarity and save space.
## Solution
Simplifies `FunctionSystem`'s layout by using a single
`Option<FunctionSystemState>` for state that must be initialized before
running, and saves a byte by removing the need to store an enum tag.
Additionally, calling `System::run` on an uninitialized `System` will
now give a more descriptive message prior to verifying the `WorldId`.
## Testing
Ran CI checks locally.
# Objective
In the [*Similar parameters* section of
`Query`](https://dev-docs.bevyengine.org/bevy/ecs/prelude/struct.Query.html#similar-parameters),
the doc link for `Single` actually links to `Query::single`, and
`Option<Single>` just links to `Option`. They should both link to
`Single`!
The first link is broken because there is a reference-style link defined
for `single`, but not for `Single`, and rustdoc treats the link as
case-insensitive for some reason.
## Solution
Fix the links!
## Testing
I built the docs locally with `cargo doc` and tested the links.
# Objective
Fixes#16266
## Solution
Added an `UnregisterSystem` command struct and
`Commands::unregister_system`. Also renamed `World::remove_system` and
`World::remove_system_cached` to `World::unregister_*`
## Testing
It's a fairly simple change, but I tested locally to ensure it actually
works.
---------
Co-authored-by: Benjamin Brienen <benjamin.brienen@outlook.com>
# Objective
Bevy seems to want to standardize on "American English" spellings. Not
sure if this is laid out anywhere in writing, but see also #15947.
While perusing the docs for `typos`, I noticed that it has a `locale`
config option and tried it out.
## Solution
Switch to `en-us` locale in the `typos` config and run `typos -w`
## Migration Guide
The following methods or fields have been renamed from `*dependants*` to
`*dependents*`.
- `ProcessorAssetInfo::dependants`
- `ProcessorAssetInfos::add_dependant`
- `ProcessorAssetInfos::non_existent_dependants`
- `AssetInfo::dependants_waiting_on_load`
- `AssetInfo::dependants_waiting_on_recursive_dep_load`
- `AssetInfos::loader_dependants`
- `AssetInfos::remove_dependants_and_labels`
# Objective
Another clippy-lint fix: the goal is so that `ci lints` actually
displays the problems that a contributor caused, and not a bunch of
existing stuff in the repo. (when run on nightly)
## Solution
This fixes all but the `clippy::needless_lifetimes` lint, which will
result in substantially more fixes and be in other PR(s). I also
explicitly allow `non_local_definitions` since it is [not working
correctly, but will be
fixed](https://github.com/rust-lang/rust/issues/131643).
A few things were manually fixed: for example, some places had an
explicitly defined `div_ceil` function that was used, which is no longer
needed since this function is stable on unsigned integers. Also, empty
lines in doc comments were handled individually.
## Testing
I ran `cargo clippy --workspace --all-targets --all-features --fix
--allow-staged` with the `clippy::needless_lifetimes` lint marked as
`allow` in `Cargo.toml` to avoid fixing that too. It now passes with all
but the listed lint.
# Objective
- closes#15866
## Solution
- Simply migrate where possible.
## Testing
- Expect that CI will do most of the work. Examples is another way of
testing this, as most of the work is in that area.
---
## Notes
For now, this PR doesn't migrate `QueryState::single` and friends as for
now, this look like another issue. So for example, QueryBuilders that
used single or `World::query` that used single wasn't migrated. If there
is a easy way to migrate those, please let me know.
Most of the uses of `Query::single` were removed, the only other uses
that I found was related to tests of said methods, so will probably be
removed when we remove `Query::single`.
# Objective
`insert_or_spawn_batch` exists, but a version for just inserting doesn't
- Closes#2693
- Closes#8384
- Adopts/supersedes #8600
## Solution
Add `insert_batch`, along with the most common `insert` variations:
- `World::insert_batch`
- `World::insert_batch_if_new`
- `World::try_insert_batch`
- `World::try_insert_batch_if_new`
- `Commands::insert_batch`
- `Commands::insert_batch_if_new`
- `Commands::try_insert_batch`
- `Commands::try_insert_batch_if_new`
## Testing
Added tests, and added a benchmark for `insert_batch`.
Performance is slightly better than `insert_or_spawn_batch` when only
inserting:
<details>
<summary>old benchmark</summary>
This was before reworking it to remove the `UnsafeWorldCell`:
</details>
---
## Showcase
Usage is the same as `insert_or_spawn_batch`:
```
use bevy_ecs::{entity::Entity, world::World, component::Component};
#[derive(Component)]
struct A(&'static str);
#[derive(Component, PartialEq, Debug)]
struct B(f32);
let mut world = World::new();
let entity_a = world.spawn_empty().id();
let entity_b = world.spawn_empty().id();
world.insert_batch([
(entity_a, (A("a"), B(0.0))),
(entity_b, (A("b"), B(1.0))),
]);
assert_eq!(world.get::<B>(entity_a), Some(&B(0.0)));
```
**Ready for review. Examples migration progress: 100%.**
# Objective
- Implement https://github.com/bevyengine/bevy/discussions/15014
## Solution
This implements [cart's
proposal](https://github.com/bevyengine/bevy/discussions/15014#discussioncomment-10574459)
faithfully except for one change. I separated `TextSpan` from
`TextSpan2d` because `TextSpan` needs to require the `GhostNode`
component, which is a `bevy_ui` component only usable by UI.
Extra changes:
- Added `EntityCommands::commands_mut` that returns a mutable reference.
This is a blocker for extension methods that return something other than
`self`. Note that `sickle_ui`'s `UiBuilder::commands` returns a mutable
reference for this reason.
## Testing
- [x] Text examples all work.
---
## Showcase
TODO: showcase-worthy
## Migration Guide
TODO: very breaking
### Accessing text spans by index
Text sections are now text sections on different entities in a
hierarchy, Use the new `TextReader` and `TextWriter` system parameters
to access spans by index.
Before:
```rust
fn refresh_text(mut query: Query<&mut Text, With<TimeText>>, time: Res<Time>) {
let text = query.single_mut();
text.sections[1].value = format_time(time.elapsed());
}
```
After:
```rust
fn refresh_text(
query: Query<Entity, With<TimeText>>,
mut writer: UiTextWriter,
time: Res<Time>
) {
let entity = query.single();
*writer.text(entity, 1) = format_time(time.elapsed());
}
```
### Iterating text spans
Text spans are now entities in a hierarchy, so the new `UiTextReader`
and `UiTextWriter` system parameters provide ways to iterate that
hierarchy. The `UiTextReader::iter` method will give you a normal
iterator over spans, and `UiTextWriter::for_each` lets you visit each of
the spans.
---------
Co-authored-by: ickshonpe <david.curthoys@googlemail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- Closes#15752
Calling the functions `App::observe` and `World::observe` doesn't make
sense because you're not "observing" the `App` or `World`, you're adding
an observer that listens for an event that occurs *within* the `World`.
We should rename them to better fit this.
## Solution
Renames:
- `App::observe` -> `App::add_observer`
- `World::observe` -> `World::add_observer`
- `Commands::observe` -> `Commands::add_observer`
- `EntityWorldMut::observe_entity` -> `EntityWorldMut::observe`
(Note this isn't a breaking change as the original rename was introduced
earlier this cycle.)
## Testing
Reusing current tests.
# Objective
After merging retained rendering world #15320, we now have a good way of
creating a link between worlds (*HIYAA intensifies*). This means that
`get_or_spawn` is no longer necessary for that function. Entity should
be opaque as the warning above `get_or_spawn` says. This is also part of
#15459.
I'm deprecating `get_or_spawn_batch` in a different PR in order to keep
the PR small in size.
## Solution
Deprecate `get_or_spawn` and replace it with `get_entity` in most
contexts. If it's possible to query `&RenderEntity`, then the entity is
synced and `render_entity.id()` is initialized in the render world.
## Migration Guide
If you are given an `Entity` and you want to do something with it, use
`Commands.entity(...)` or `World.entity(...)`. If instead you want to
spawn something use `Commands.spawn(...)` or `World.spawn(...)`. If you
are not sure if an entity exists, you can always use `get_entity` and
match on the `Option<...>` that is returned.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Following the pattern established in #15593, we can reduce the API
surface of `World` by providing a single function to grab both a
singular entity reference, or multiple entity references.
## Solution
The following functions can now also take multiple entity IDs and will
return multiple entity references back:
- `World::entity`
- `World::get_entity`
- `World::entity_mut`
- `World::get_entity_mut`
- `DeferredWorld::entity_mut`
- `DeferredWorld::get_entity_mut`
If you pass in X, you receive Y:
- give a single `Entity`, receive a single `EntityRef`/`EntityWorldMut`
(matches current behavior)
- give a `[Entity; N]`/`&[Entity; N]` (array), receive an equally-sized
`[EntityRef; N]`/`[EntityMut; N]`
- give a `&[Entity]` (slice), receive a
`Vec<EntityRef>`/`Vec<EntityMut>`
- give a `&EntityHashSet`, receive a
`EntityHashMap<EntityRef>`/`EntityHashMap<EntityMut>`
Note that `EntityWorldMut` is only returned in the single-entity case,
because having multiple at the same time would lead to UB. Also,
`DeferredWorld` receives an `EntityMut` in the single-entity case
because it does not allow structural access.
## Testing
- Added doc-tests on `World::entity`, `World::entity_mut`, and
`DeferredWorld::entity_mut`
- Added tests for aliased mutability and entity existence
---
## Showcase
<details>
<summary>Click to view showcase</summary>
The APIs for fetching `EntityRef`s and `EntityMut`s from the `World`
have been unified.
```rust
// This code will be referred to by subsequent code blocks.
let world = World::new();
let e1 = world.spawn_empty().id();
let e2 = world.spawn_empty().id();
let e3 = world.spawn_empty().id();
```
Querying for a single entity remains mostly the same:
```rust
// 0.14
let eref: EntityRef = world.entity(e1);
let emut: EntityWorldMut = world.entity_mut(e1);
let eref: Option<EntityRef> = world.get_entity(e1);
let emut: Option<EntityWorldMut> = world.get_entity_mut(e1);
// 0.15
let eref: EntityRef = world.entity(e1);
let emut: EntityWorldMut = world.entity_mut(e1);
let eref: Result<EntityRef, Entity> = world.get_entity(e1);
let emut: Result<EntityWorldMut, Entity> = world.get_entity_mut(e1);
```
Querying for multiple entities with an array has changed:
```rust
// 0.14
let erefs: [EntityRef; 2] = world.many_entities([e1, e2]);
let emuts: [EntityMut; 2] = world.many_entities_mut([e1, e2]);
let erefs: Result<[EntityRef; 2], Entity> = world.get_many_entities([e1, e2]);
let emuts: Result<[EntityMut; 2], QueryEntityError> = world.get_many_entities_mut([e1, e2]);
// 0.15
let erefs: [EntityRef; 2] = world.entity([e1, e2]);
let emuts: [EntityMut; 2] = world.entity_mut([e1, e2]);
let erefs: Result<[EntityRef; 2], Entity> = world.get_entity([e1, e2]);
let emuts: Result<[EntityMut; 2], EntityFetchError> = world.get_entity_mut([e1, e2]);
```
Querying for multiple entities with a slice has changed:
```rust
let ids = vec![e1, e2, e3]);
// 0.14
let erefs: Result<Vec<EntityRef>, Entity> = world.get_many_entities_dynamic(&ids[..]);
let emuts: Result<Vec<EntityMut>, QueryEntityError> = world.get_many_entities_dynamic_mut(&ids[..]);
// 0.15
let erefs: Result<Vec<EntityRef>, Entity> = world.get_entity(&ids[..]);
let emuts: Result<Vec<EntityMut>, EntityFetchError> = world.get_entity_mut(&ids[..]);
let erefs: Vec<EntityRef> = world.entity(&ids[..]); // Newly possible!
let emuts: Vec<EntityMut> = world.entity_mut(&ids[..]); // Newly possible!
```
Querying for multiple entities with an `EntityHashSet` has changed:
```rust
let set = EntityHashSet::from_iter([e1, e2, e3]);
// 0.14
let emuts: Result<Vec<EntityMut>, QueryEntityError> = world.get_many_entities_from_set_mut(&set);
// 0.15
let emuts: Result<EntityHashMap<EntityMut>, EntityFetchError> = world.get_entity_mut(&set);
let erefs: Result<EntityHashMap<EntityRef>, EntityFetchError> = world.get_entity(&set); // Newly possible!
let emuts: EntityHashMap<EntityMut> = world.entity_mut(&set); // Newly possible!
let erefs: EntityHashMap<EntityRef> = world.entity(&set); // Newly possible!
```
</details>
## Migration Guide
- `World::get_entity` now returns `Result<_, Entity>` instead of
`Option<_>`.
- Use `world.get_entity(..).ok()` to return to the previous behavior.
- `World::get_entity_mut` and `DeferredWorld::get_entity_mut` now return
`Result<_, EntityFetchError>` instead of `Option<_>`.
- Use `world.get_entity_mut(..).ok()` to return to the previous
behavior.
- Type inference for `World::entity`, `World::entity_mut`,
`World::get_entity`, `World::get_entity_mut`,
`DeferredWorld::entity_mut`, and `DeferredWorld::get_entity_mut` has
changed, and might now require the input argument's type to be
explicitly written when inside closures.
- The following functions have been deprecated, and should be replaced
as such:
- `World::many_entities` -> `World::entity::<[Entity; N]>`
- `World::many_entities_mut` -> `World::entity_mut::<[Entity; N]>`
- `World::get_many_entities` -> `World::get_entity::<[Entity; N]>`
- `World::get_many_entities_dynamic` -> `World::get_entity::<&[Entity]>`
- `World::get_many_entities_mut` -> `World::get_entity_mut::<[Entity;
N]>`
- The equivalent return type has changed from `Result<_,
QueryEntityError>` to `Result<_, EntityFetchError>`
- `World::get_many_entities_dynamic_mut` ->
`World::get_entity_mut::<&[Entity]>1
- The equivalent return type has changed from `Result<_,
QueryEntityError>` to `Result<_, EntityFetchError>`
- `World::get_many_entities_from_set_mut` ->
`World::get_entity_mut::<&EntityHashSet>`
- The equivalent return type has changed from `Result<Vec<EntityMut>,
QueryEntityError>` to `Result<EntityHashMap<EntityMut>,
EntityFetchError>`. If necessary, you can still convert the
`EntityHashMap` into a `Vec`.
## Objective
The new Required Components feature (#14791) in Bevy allows spawning a
fixed set of components with a single method with cool require macro.
However, there's currently no corresponding method to remove all those
components together. This makes it challenging to keep insertion and
removal code in sync, especially for simple using cases.
```rust
#[derive(Component)]
#[require(Y)]
struct X;
#[derive(Component, Default)]
struct Y;
world.entity_mut(e).insert(X); // Spawns both X and Y
world.entity_mut(e).remove::<X>();
world.entity_mut(e).remove::<Y>(); // We need to manually remove dependencies without any sync with the `require` macro
```
## Solution
Simplifies component management by providing operations for removal
required components.
This PR introduces simple 'footgun' methods to removes all components of
this bundle and its required components.
Two new methods are introduced:
For Commands:
```rust
commands.entity(e).remove_with_requires::<B>();
```
For World:
```rust
world.entity_mut(e).remove_with_requires::<B>();
```
For performance I created new field in Bundels struct. This new field
"contributed_bundle_ids" contains cached ids for dynamic bundles
constructed from bundle_info.cintributed_components()
## Testing
The PR includes three test cases:
1. Removing a single component with requirements using World.
2. Removing a bundle with requirements using World.
3. Removing a single component with requirements using Commands.
4. Removing a single component with **runtime** requirements using
Commands
These tests ensure the feature works as expected across different
scenarios.
## Showcase
Example:
```rust
use bevy_ecs::prelude::*;
#[derive(Component)]
#[require(Y)]
struct X;
#[derive(Component, Default)]
#[require(Z)]
struct Y;
#[derive(Component, Default)]
struct Z;
#[derive(Component)]
struct W;
let mut world = World::new();
// Spawn an entity with X, Y, Z, and W components
let entity = world.spawn((X, W)).id();
assert!(world.entity(entity).contains::<X>());
assert!(world.entity(entity).contains::<Y>());
assert!(world.entity(entity).contains::<Z>());
assert!(world.entity(entity).contains::<W>());
// Remove X and required components Y, Z
world.entity_mut(entity).remove_with_requires::<X>();
assert!(!world.entity(entity).contains::<X>());
assert!(!world.entity(entity).contains::<Y>());
assert!(!world.entity(entity).contains::<Z>());
assert!(world.entity(entity).contains::<W>());
```
## Motivation for PR
#15580
## Performance
I made simple benchmark
```rust
let mut world = World::default();
let entity = world.spawn_empty().id();
let steps = 100_000_000;
let start = std::time::Instant::now();
for _ in 0..steps {
world.entity_mut(entity).insert(X);
world.entity_mut(entity).remove::<(X, Y, Z, W)>();
}
let end = std::time::Instant::now();
println!("normal remove: {:?} ", (end - start).as_secs_f32());
println!("one remove: {:?} micros", (end - start).as_secs_f64() / steps as f64 * 1_000_000.0);
let start = std::time::Instant::now();
for _ in 0..steps {
world.entity_mut(entity).insert(X);
world.entity_mut(entity).remove_with_requires::<X>();
}
let end = std::time::Instant::now();
println!("remove_with_requires: {:?} ", (end - start).as_secs_f32());
println!("one remove_with_requires: {:?} micros", (end - start).as_secs_f64() / steps as f64 * 1_000_000.0);
```
Output:
CPU: Amd Ryzen 7 2700x
```bash
normal remove: 17.36135
one remove: 0.17361348299999999 micros
remove_with_requires: 17.534006
one remove_with_requires: 0.17534005400000002 micros
```
NOTE: I didn't find any tests or mechanism in the repository to update
BundleInfo after creating new runtime requirements with an existing
BundleInfo. So this PR also does not contain such logic.
## Future work (outside this PR)
Create cache system for fast removing components in "safe" mode, where
"safe" mode is remove only required components that will be no longer
required after removing root component.
---------
Co-authored-by: a.yamaev <a.yamaev@smartengines.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Support accessing dynamic resources in a dynamic system, including
accessing them by component id. This is similar to how dynamic
components can be queried using `Query<FilteredEntityMut>`.
## Solution
Create `FilteredResources` and `FilteredResourcesMut` types that act
similar to `FilteredEntityRef` and `FilteredEntityMut` and that can be
used as system parameters.
## Example
```rust
// Use `FilteredResourcesParamBuilder` to declare access to resources.
let system = (FilteredResourcesParamBuilder::new(|builder| {
builder.add_read::<B>().add_read::<C>();
}),)
.build_state(&mut world)
.build_system(resource_system);
world.init_resource::<A>();
world.init_resource::<C>();
fn resource_system(res: FilteredResources) {
// The resource exists, but we have no access, so we can't read it.
assert!(res.get::<A>().is_none());
// The resource doesn't exist, so we can't read it.
assert!(res.get::<B>().is_none());
// The resource exists and we have access, so we can read it.
let c = res.get::<C>().unwrap();
// The type parameter can be left out if it can be determined from use.
let c: Res<C> = res.get().unwrap();
}
```
## Future Work
As a follow-up PR, `ReflectResource` can be modified to take `impl
Into<FilteredResources>`, similar to how `ReflectComponent` takes `impl
Into<FilteredEntityRef>`. That will allow dynamic resources to be
accessed using reflection.
# Objective
The current observers have some unfortunate footguns where you can end
up confused about what is actually being observed. For apps you can
chain observe like `app.observe(..).observe(..)` which works like you
would expect, but if you try the same with world the first `observe()`
will return the `EntityWorldMut` for the created observer, and the
second `observe()` will only observe on the observer entity. It took
several hours for multiple people on discord to figure this out, which
is not a great experience.
## Solution
Rename `observe` on entities to `observe_entity`. It's slightly more
verbose when you know you have an entity, but it feels right to me that
observers for specific things have more specific naming, and it prevents
this issue completely.
Another possible solution would be to unify `observe` on `App` and
`World` to have the same kind of return type, but I'm not sure exactly
what that would look like.
## Testing
Simple name change, so only concern is docs really.
---
## Migration Guide
The `observe()` method on entities has been renamed to
`observe_entity()` to prevent confusion about what is being observed in
some cases.
# Objective
Fixes#14511.
`despawn` allows you to remove entities from the world. However, if the
entity does not exist, it emits a warning. This may not be intended
behavior for many users who have use cases where they need to call
`despawn` regardless of if the entity actually exists (see the issue),
or don't care in general if the entity already doesn't exist.
(Also trying to gauge interest on if this feature makes sense, I'd
personally love to have it, but I could see arguments that this might be
a footgun. Just trying to help here 😄 If there's no contention I could
also implement this for `despawn_recursive` and `despawn_descendants` in
the same PR)
## Solution
Add `try_despawn`, `try_despawn_recursive` and
`try_despawn_descendants`.
Modify `World::despawn_with_caller` to also take in a `warn` boolean
argument, which is then considered when logging the warning. Set
`log_warning` to `true` in the case of `despawn`, and `false` in the
case of `try_despawn`.
## Testing
Ran `cargo run -p ci` on macOS, it seemed fine.
# Objective
System param validation warnings should be configurable and default to
"warn once" (per system).
Fixes: #15391
## Solution
`SystemMeta` is given a new `ParamWarnPolicy` field.
The policy decides whether warnings will be emitted by each system param
when it fails validation.
The policy is updated by the system after param validation fails.
Example warning:
```
2024-09-30T18:10:04.740749Z WARN bevy_ecs::system::function_system: System fallible_params::do_nothing_fail_validation will not run because it requested inaccessible system parameter Single<(), (With<Player>, With<Enemy>)>
```
Currently, only the first invalid parameter is displayed.
Warnings can be disabled on function systems using
`.param_never_warn()`.
(there is also `.with_param_warn_policy(policy)`)
## Testing
Ran `fallible_params` example.
---------
Co-authored-by: SpecificProtagonist <vincentjunge@posteo.net>
As discussed in #15521
- Partial revert of #14897, reverting the change to the methods to
consume `self`
- The `insert_if` method is kept
The migration guide of #14897 should be removed
Closes#15521
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Add a `Populated` system parameter that acts like `Query`, but prevents
system from running if there are no matching entities.
Fixes: #15302
## Solution
Implement the system param which newtypes the `Query`.
The only change is new validation, which fails if query is empty.
The new system param is used in `fallible_params` example.
## Testing
Ran `fallible_params` example.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Improve the documentation of `SystemParamBuilder`. Not all builder types
have documentation, and the documentation is spread around and not
linked together well.
## Solution
Reorganize `SystemParamBuilder` docs and examples. All builder types now
have their own examples, and the list of builder types is linked from
the `SystemParamBuilder` trait. Add some examples to `FilteredEntityRef`
and `FilteredEntityMut` so that `QueryParamBuilder` can reference them.
# Objective
Fixes#15394
## Solution
Observers now validate params.
System registry has a new error variant for when system running fails
due to invalid parameters.
Run once now returns a `Result<Out, RunOnceError>` instead of `Out`.
This is more inline with system registry, which also returns a result.
I'll address warning messages in #15500.
## Testing
Added one test for each case.
---
## Migration Guide
- `RunSystemOnce::run_system_once` and
`RunSystemOnce::run_system_once_with` now return a `Result<Out>` instead
of just `Out`
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Zachary Harrold <zac@harrold.com.au>
# Objective
Add the following system params:
- `QuerySingle<D, F>` - Valid if only one matching entity exists,
- `Option<QuerySingle<D, F>>` - Valid if zero or one matching entity
exists.
As @chescock pointed out, we don't need `Mut` variants.
Fixes: #15264
## Solution
Implement the type and both variants of system params.
Also implement `ReadOnlySystemParam` for readonly queries.
Added a new ECS example `fallible_params` which showcases `SingleQuery`
usage.
In the future we might want to add `NonEmptyQuery`,
`NonEmptyEventReader` and `Res` to it (or maybe just stop at mentioning
it).
## Testing
Tested with the example.
There is a lot of warning spam so we might want to implement #15391.
> [!NOTE]
> This is my first PR, so if something is incorrect
> or missing, please let me know :3
# Objective
- Clarifies `spawn`, `spawn_batch` and `ParallelCommands` docs about
performance and use cases
- Fixes#15472
## Solution
Add comments to `spawn`, `spawn_batch` and `ParallelCommands` to clarify
the
intended use case and link to other/better ways of doing spawning things
for
certain use cases.
# Objective
- Fixes#6370
- Closes#6581
## Solution
- Added the following lints to the workspace:
- `std_instead_of_core`
- `std_instead_of_alloc`
- `alloc_instead_of_core`
- Used `cargo +nightly fmt` with [item level use
formatting](https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=#Item%5C%3A)
to split all `use` statements into single items.
- Used `cargo clippy --workspace --all-targets --all-features --fix
--allow-dirty` to _attempt_ to resolve the new linting issues, and
intervened where the lint was unable to resolve the issue automatically
(usually due to needing an `extern crate alloc;` statement in a crate
root).
- Manually removed certain uses of `std` where negative feature gating
prevented `--all-features` from finding the offending uses.
- Used `cargo +nightly fmt` with [crate level use
formatting](https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=#Crate%5C%3A)
to re-merge all `use` statements matching Bevy's previous styling.
- Manually fixed cases where the `fmt` tool could not re-merge `use`
statements due to conditional compilation attributes.
## Testing
- Ran CI locally
## Migration Guide
The MSRV is now 1.81. Please update to this version or higher.
## Notes
- This is a _massive_ change to try and push through, which is why I've
outlined the semi-automatic steps I used to create this PR, in case this
fails and someone else tries again in the future.
- Making this change has no impact on user code, but does mean Bevy
contributors will be warned to use `core` and `alloc` instead of `std`
where possible.
- This lint is a critical first step towards investigating `no_std`
options for Bevy.
---------
Co-authored-by: François Mockers <francois.mockers@vleue.com>
# Objective
- Fixes#15451
## Migration Guide
- `World::init_component` has been renamed to `register_component`.
- `World::init_component_with_descriptor` has been renamed to
`register_component_with_descriptor`.
- `World::init_bundle` has been renamed to `register_bundle`.
- `Components::init_component` has been renamed to `register_component`.
- `Components::init_component_with_descriptor` has been renamed to
`register_component_with_descriptor`.
- `Components::init_resource` has been renamed to `register_resource`.
- `Components::init_non_send` had been renamed to `register_non_send`.
# Objective
- #15331
## Solution
-Just changed it to Trigger since the function signature shows it's just
a wrapper trait
## Testing
Will let tests pass
---------
Co-authored-by: Fernan Lukban <fernanlukban@gmail.co>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Antony <antony.m.3012@gmail.com>
# Objective
- Fixes#15373
- Fixes
https://github.com/bevyengine/bevy/pull/14920#issuecomment-2370428013
## Solution
- Make `IntoSystem::pipe` and `IntoSystem::map` return two new
(possibly-ZST) types that implement `IntoSystem` and whose `into_system`
method return the systems that were previously being returned by
`IntoSystem::pipe` and `IntoSystem::map`
- Don't eagerly call `IntoSystem::into_system` on the argument given to
`RunSystemCachedWith::new` to avoid losing its ZST-ness
## Testing
- Added a regression test for each issue
## Migration Guide
- `IntoSystem::pipe` and `IntoSystem::map` now return `IntoPipeSystem`
and `IntoAdapterSystem` instead of `PipeSystem` and `AdapterSystem`.
Most notably these types don't implement `System` but rather only
`IntoSystem`.
# Objective
- Fixes#14924
- Closes#9584
## Solution
- We introduce a new trait, `SystemInput`, that serves as a type
function from the `'static` form of the input, to its lifetime'd
version, similarly to `SystemParam` or `WorldQuery`.
- System functions now take the lifetime'd wrapped version,
`SystemInput::Param<'_>`, which prevents the issue presented in #14924
(i.e. `InRef<T>`).
- Functions for running systems now take the lifetime'd unwrapped
version, `SystemInput::Inner<'_>` (i.e. `&T`).
- Due to the above change, system piping had to be re-implemented as a
standalone type, rather than `CombinatorSystem` as it was previously.
- Removes the `Trigger<'static, E, B>` transmute in observer runner
code.
## Testing
- All current tests pass.
- Added additional tests and doc-tests.
---
## Showcase
```rust
let mut world = World::new();
let mut value = 2;
// Currently possible:
fn square(In(input): In<usize>) -> usize {
input * input
}
value = world.run_system_once_with(value, square);
// Now possible:
fn square_mut(InMut(input): InMut<usize>) {
*input *= *input;
}
world.run_system_once_with(&mut value, square_mut);
// Or:
fn square_ref(InRef(input): InRef<usize>) -> usize {
*input * *input
}
value = world.run_system_once_with(&value, square_ref);
```
## Migration Guide
- All current explicit usages of the following types must be changed in
the way specified:
- `SystemId<I, O>` to `SystemId<In<I>, O>`
- `System<In = T>` to `System<In = In<T>>`
- `IntoSystem<I, O, M>` to `IntoSystem<In<I>, O, M>`
- `Condition<M, T>` to `Condition<M, In<T>>`
- `In<Trigger<E, B>>` is no longer a valid input parameter type. Use
`Trigger<E, B>` directly, instead.
---------
Co-authored-by: Giacomo Stevanato <giaco.stevanato@gmail.com>
# Objective
The goal of this PR is to introduce `SystemParam` validation in order to
reduce runtime panics.
Fixes#15265
## Solution
`SystemParam` now has a new method `validate_param(...) -> bool`, which
takes immutable variants of `get_param` arguments. The returned value
indicates whether the parameter can be acquired from the world. If
parameters cannot be acquired for a system, it won't be executed,
similarly to run conditions. This reduces panics when using params like
`Res`, `ResMut`, etc. as well as allows for new, ergonomic params like
#15264 or #15302.
Param validation happens at the level of executors. All validation
happens directly before executing a system, in case of normal systems
they are skipped, in case of conditions they return false.
Warning about system skipping is primitive and subject to change in
subsequent PRs.
## Testing
Two executor tests check that all executors:
- skip systems which have invalid parameters:
- piped systems get skipped together,
- dependent systems still run correctly,
- skip systems with invalid run conditions:
- system conditions have invalid parameters,
- system set conditions have invalid parameters.
# Objective
Working with `World` is painful due to lifetime issues and a lack of
ergonomics, so you may want to delegate to the system API. Your current
options are:
- `world.run_system_once`, which initializes the system each time it's
called (performance cost) and doesn't support `Local`. The docs
recommend users not use this method outside of diagnostic use cases like
unit tests.
- `world.run_system`, which requires you to register the system and
store the `SystemId` somewhere (made easier by implementing `FromWorld`
for a newtyped `Local`, unless you're in e.g. a custom `Command` impl).
These options work, but you're choosing between a performance cost and
an ergonomic challenge.
## Solution
Provide a cached `run_system` API that accepts an `S: IntoSystem` and
checks for a `CachedSystemId<S::System>(SystemId)` resource. If it
doesn't exist, it will register the system and save its `SystemId` in
that resource.
In other words, it hides the "save the `SystemId` in a `Local` or
`Resource`" pattern as an implementation detail.
Prior work: https://github.com/bevyengine/bevy/pull/10469.
## Testing
This approach worked in a proof-of-concept:
b34ee29531/src/util/patch/run_system_cached.rs (L35).
A new unit test was added and it passes in CI.
# Objective
It's convenient to be able to modify a component if it exist, and insert
a default value if it doesn't. You can already do most of this with
`EntityCommands::insert_if_new`, and all of this using a custom command.
However, that does not spark joy in my opinion.
Closes#10669
## Solution
Introduce a new commands type `EntityEntryCommands`, along with a method
to access it, `EntityCommands::entry`.
`EntityEntryCommands` exposes a subset of the entry API (`and_modify`,
`or_insert`, etc), however it's not an enum so it doesn't allow pattern
matching. Also, `or_insert` won't return the component because it's all
based on commands.
## Testing
Added a new test `entity_commands_entry`.
---
## Showcase
```rust
commands
.entity(player)
.entry::<Level>()
.and_modify(|mut lvl| lvl.0 += 1)
.or_default();
```
---------
Co-authored-by: Jan Hohenheim <jan@hohenheim.ch>
Enabled `check-private-items` in `clippy.toml` and then fixed the
resulting errors. Most of these were simply misformatted and of the
remaining:
- ~Added `#[allow(clippy::missing_safety_doc)]` to~ Removed unsafe from
a pair of functions in `bevy_utils/futures` which are only unsafe so
that they can be passed to a function which requires `unsafe fn`
- Removed `unsafe` from `UnsafeWorldCell::observers` as from what I can
tell it is always safe like `components`, `bundles` etc. (this should be
checked)
- Added safety docs to:
- `Bundles::get_storage_unchecked`: Based on the function that writes to
`dynamic_component_storages`
- `Bundles::get_storages_unchecked`: Based on the function that writes
to `dynamic_bundle_storages`
- `QueryIterationCursor::init_empty`: Duplicated from `init`
- `QueryIterationCursor::peek_last`: Thanks Giooschi (also added
internal unsafe blocks)
- `tests::drop_ptr`: Moved safety comment out to the doc string
This lint would also apply to `missing_errors_doc`, `missing_panics_doc`
and `unnecessary_safety_doc` if we chose to enable any of those at some
point, although there is an open
[issue](https://github.com/rust-lang/rust-clippy/issues/13074) to
separate these options.
This commit adds two new `WorldQuery` types: `EntityRefExcept` and
`EntityMutExcept`. These types work just like `EntityRef` and
`EntityMut`, but they prevent access to a statically-specified list of
components. For example, `EntityMutExcept<(AnimationPlayer,
Handle<AnimationGraph>)>` provides mutable access to all components
except for `AnimationPlayer` and `Handle<AnimationGraph>`. These types
are useful when you need to be able to process arbitrary queries while
iterating over the results of another `EntityMut` query.
The motivating use case is *generalized animation*, which is an upcoming
feature that allows animation of any component property, not just
rotation, translation, scaling, or morph weights. To implement this, we
must change the current `AnyOf<(&mut Transform, &mut MorphWeights)>` to
instead be `EntityMutExcept<(AnimationPlayer, Handle<AnimationGraph>)>`.
It's possible to use `FilteredEntityMut` in conjunction with a
dynamically-generated system instead, but `FilteredEntityMut` isn't
optimized for the use case of a large number of allowed components
coupled with a small set of disallowed components. No amount of
optimization of `FilteredEntityMut` produced acceptable performance on
the `many_foxes` benchmark. `Query<EntityMut, Without<AnimationPlayer>>`
will not suffice either, as it's legal and idiomatic for an
`AnimationTarget` and an `AnimationPlayer` to coexist on the same
entity.
An alternate proposal was to implement a somewhat-more-general
`Except<Q, CL>` feature, where Q is a `WorldQuery` and CL is a
`ComponentList`. I wasn't able to implement that proposal in a
reasonable way, because of the fact that methods like
`EntityMut::get_mut` and `EntityRef::get` are inherent methods instead
of methods on `WorldQuery`, and therefore there was no way to delegate
methods like `get` and `get_mut` to the inner query in a generic way.
Refactoring those methods into a trait would probably be possible.
However, I didn't see a use case for a hypothetical `Except` with
arbitrary queries: `Query<Except<(&Transform, &Visibility),
Visibility>>` would just be a complicated equivalent to
`Query<&Transform>`, for instance. So, out of a desire for simplicity, I
omitted a generic `Except` mechanism.
I've tested the performance of generalized animation on `many_foxes` and
found that, with this patch, `animate_targets` has a 7.4% slowdown over
`main`. With `FilteredEntityMut` optimized to use `Arc<Access>`, the
slowdown is 75.6%, due to contention on the reference count. Without
`Arc<Access>`, the slowdown is even worse, over 2x.
## Testing
New tests have been added that check that `EntityRefExcept` and
`EntityMutExcept` allow and disallow access to components properly and
that the query engine can correctly reject conflicting queries involving
those types.
A Tracy profile of `many_foxes` with 10,000 foxes showing generalized
animation using `FilteredEntityMut` (red) vs. main (yellow) is as
follows:
A Tracy profile of `many_foxes` with 10,000 foxes showing generalized
animation using this `EntityMutExcept` (yellow) vs. main (red) is as
follows:
# Objective
- Fixes#15106
## Solution
- Trivial refactor to rename the method. The duplicate method `push` was
removed as well. This will simpify the API and make the semantics more
clear. `Add` implies that the action happens immediately, whereas in
reality, the command is queued to be run eventually.
- `ChildBuilder::add_command` has similarly been renamed to
`queue_command`.
## Testing
Unit tests should suffice for this simple refactor.
---
## Migration Guide
- `Commands::add` and `Commands::push` have been replaced with
`Commnads::queue`.
- `ChildBuilder::add_command` has been renamed to
`ChildBuilder::queue_command`.
# Objective
- Adds the missing API commands `insert_if_new_and` and
`try_insert_if_new_and` (resolves#15105)
- Adds some test coverage for existing insert commands
## Testing
- Implemented additional unit tests to add coverage
# Objective
Right now, `DynSystemParam::downcast()` always requires the type
parameter to be specified with a turbofish. Make it so that it can be
inferred from the use of the return value, like:
```rust
fn expects_res_a(mut param: DynSystemParam) {
let res: Res<A> = param.downcast().unwrap();
}
```
## Solution
The reason this doesn't currently work is that the type parameter is a
`'static` version of the `SystemParam` so that it can be used with
`Any::downcast_mut()`. Change the method signature so that the type
parameter matches the return type, and use `T::Item<'static, 'static>`
to get the `'static` version. That means we wind up returning a
`T::Item<'static, 'static>::Item<'w, 's>`, so constrain that to be equal
to `T`. That works with every `SystemParam` implementation, since they
have `T::Item == T` up to lifetimes.
# Objective
A previous issue describes the same problem: #14248.
This particular link was seemingly missed by #14276.
## Solution
- Search repo for `bevyengine.org/learn/errors/#`
- Remove `#`
- Verify link goes to right place
# Objective
Make the documentation for `SystemParamBuilder` nicer by combining the
tuple implementations into a single line of documentation.
## Solution
Use `#[doc(fake_variadic)]` for `SystemParamBuilder` tuple impls.
(This got missed originally because #14050 and #14703 were open at the
same time.)
# Objective
Allow `SystemParamBuilder` implementations for custom system parameters
created using `#[derive(SystemParam)]`.
## Solution
Extend the derive macro to accept a `#[system_param(builder)]`
attribute. When present, emit a builder type with a field corresponding
to each field of the param.
## Example
```rust
#[derive(SystemParam)]
#[system_param(builder)]
struct CustomParam<'w, 's> {
query: Query<'w, 's, ()>,
local: Local<'s, usize>,
}
let system = (CustomParamBuilder {
local: LocalBuilder(100),
query: QueryParamBuilder::new(|builder| {
builder.with::<A>();
}),
},)
.build_state(&mut world)
.build_system(|param: CustomParam| *param.local + param.query.iter().count());
```
# Objective
When building a system from `SystemParamBuilder`s and defining the
system as a closure, the compiler should be able to infer the parameter
types from the builder types.
## Solution
Create methods for each arity that take an argument that implements both
`SystemParamFunction` as well as `FnMut(SystemParamItem<P>,...)`. The
explicit `FnMut` constraint will allow the compiler to infer the
necessary higher-ranked lifetimes along with the parameter types.
I wanted to show that this was possible, but I can't tell whether it's
worth the complexity. It requires a separate method for each arity,
which pollutes the docs a bit:
## Example
```rust
let system = (LocalBuilder(0u64), ParamBuilder::local::<u64>())
.build_state(&mut world)
.build_system(|a, b| *a + *b + 1);
```
# Objective
sending events tends to be low-frequency so ergonomics can be
prioritized over efficiency.
add `Commands::send_event` to send any type of event without needing a
writer in hand.
i don't know how we feel about these kind of ergonomic things, i add
this to all my projects and find it useful. adding `mut
this_particular_event_writer: EventWriter<ThisParticularEvent>` every
time i want to send something is unnecessarily cumbersome.
it also simplifies the "send and receive in the same system" pattern
significantly.
basic example before:
```rs
fn my_func(
q: Query<(Entity, &State)>,
mut damage_event_writer: EventWriter<DamageEvent>,
mut heal_event_writer: EventWriter<HealEvent>,
) {
for (entity, state) in q.iter() {
if let Some(damage) = state.get_damage() {
damage_event_writer.send(DamageEvent { entity, damage });
}
if let Some(heal) = state.get_heal() {
heal_event_writer.send(HealEvent { entity, heal });
}
}
}
```
basic example after:
```rs
import bevy::ecs::event::SendEventEx;
fn my_func(
mut commands: Commands,
q: Query<(Entity, &State)>,
) {
for (entity, state) in q.iter() {
if let Some(damage) = state.get_damage() {
commands.send_event(DamageEvent { entity, damage });
}
if let Some(heal) = state.get_heal() {
commands.send_event(HealEvent { entity, heal });
}
}
}
```
send/receive in the same system before:
```rs
fn send_and_receive_param_set(
mut param_set: ParamSet<(EventReader<DebugEvent>, EventWriter<DebugEvent>)>,
) {
// We must collect the events to resend, because we can't access the writer while we're iterating over the reader.
let mut events_to_resend = Vec::new();
// This is p0, as the first parameter in the `ParamSet` is the reader.
for event in param_set.p0().read() {
if event.resend_from_param_set {
events_to_resend.push(event.clone());
}
}
// This is p1, as the second parameter in the `ParamSet` is the writer.
for mut event in events_to_resend {
event.times_sent += 1;
param_set.p1().send(event);
}
}
```
after:
```rs
use bevy::ecs::event::SendEventEx;
fn send_via_commands_and_receive(
mut reader: EventReader<DebugEvent>,
mut commands: Commands,
) {
for event in reader.read() {
if event.resend_via_commands {
commands.send_event(DebugEvent {
times_sent: event.times_sent + 1,
..event.clone()
});
}
}
}
```
---------
Co-authored-by: Jan Hohenheim <jan@hohenheim.ch>
## Introduction
This is the first step in my [Next Generation Scene / UI
Proposal](https://github.com/bevyengine/bevy/discussions/14437).
Fixes https://github.com/bevyengine/bevy/issues/7272#14800.
Bevy's current Bundles as the "unit of construction" hamstring the UI
user experience and have been a pain point in the Bevy ecosystem
generally when composing scenes:
* They are an additional _object defining_ concept, which must be
learned separately from components. Notably, Bundles _are not present at
runtime_, which is confusing and limiting.
* They can completely erase the _defining component_ during Bundle init.
For example, `ButtonBundle { style: Style::default(), ..default() }`
_makes no mention_ of the `Button` component symbol, which is what makes
the Entity a "button"!
* They are not capable of representing "dependency inheritance" without
completely non-viable / ergonomically crushing nested bundles. This
limitation is especially painful in UI scenarios, but it applies to
everything across the board.
* They introduce a bunch of additional nesting when defining scenes,
making them ugly to look at
* They introduce component name "stutter": `SomeBundle { component_name:
ComponentName::new() }`
* They require copious sprinklings of `..default()` when spawning them
in Rust code, due to the additional layer of nesting
**Required Components** solve this by allowing you to define which
components a given component needs, and how to construct those
components when they aren't explicitly provided.
This is what a `ButtonBundle` looks like with Bundles (the current
approach):
```rust
#[derive(Component, Default)]
struct Button;
#[derive(Bundle, Default)]
struct ButtonBundle {
pub button: Button,
pub node: Node,
pub style: Style,
pub interaction: Interaction,
pub focus_policy: FocusPolicy,
pub border_color: BorderColor,
pub border_radius: BorderRadius,
pub image: UiImage,
pub transform: Transform,
pub global_transform: GlobalTransform,
pub visibility: Visibility,
pub inherited_visibility: InheritedVisibility,
pub view_visibility: ViewVisibility,
pub z_index: ZIndex,
}
commands.spawn(ButtonBundle {
style: Style {
width: Val::Px(100.0),
height: Val::Px(50.0),
..default()
},
focus_policy: FocusPolicy::Block,
..default()
})
```
And this is what it looks like with Required Components:
```rust
#[derive(Component)]
#[require(Node, UiImage)]
struct Button;
commands.spawn((
Button,
Style {
width: Val::Px(100.0),
height: Val::Px(50.0),
..default()
},
FocusPolicy::Block,
));
```
With Required Components, we mention only the most relevant components.
Every component required by `Node` (ex: `Style`, `FocusPolicy`, etc) is
automatically brought in!
### Efficiency
1. At insertion/spawn time, Required Components (including recursive
required components) are initialized and inserted _as if they were
manually inserted alongside the given components_. This means that this
is maximally efficient: there are no archetype or table moves.
2. Required components are only initialized and inserted if they were
not manually provided by the developer. For the code example in the
previous section, because `Style` and `FocusPolicy` are inserted
manually, they _will not_ be initialized and inserted as part of the
required components system. Efficient!
3. The "missing required components _and_ constructors needed for an
insertion" are cached in the "archetype graph edge", meaning they aren't
computed per-insertion. When a component is inserted, the "missing
required components" list is iterated (and that graph edge (AddBundle)
is actually already looked up for us during insertion, because we need
that for "normal" insert logic too).
### IDE Integration
The `#[require(SomeComponent)]` macro has been written in such a way
that Rust Analyzer can provide type-inspection-on-hover and `F12` /
go-to-definition for required components.
### Custom Constructors
The `require` syntax expects a `Default` constructor by default, but it
can be overridden with a custom constructor:
```rust
#[derive(Component)]
#[require(
Node,
Style(button_style),
UiImage
)]
struct Button;
fn button_style() -> Style {
Style {
width: Val::Px(100.0),
..default()
}
}
```
### Multiple Inheritance
You may have noticed by now that this behaves a bit like "multiple
inheritance". One of the problems that this presents is that it is
possible to have duplicate requires for a given type at different levels
of the inheritance tree:
```rust
#[derive(Component)
struct X(usize);
#[derive(Component)]
#[require(X(x1))
struct Y;
fn x1() -> X {
X(1)
}
#[derive(Component)]
#[require(
Y,
X(x2),
)]
struct Z;
fn x2() -> X {
X(2)
}
// What version of X is inserted for Z?
commands.spawn(Z);
```
This is allowed (and encouraged), although this doesn't appear to occur
much in practice. First: only one version of `X` is initialized and
inserted for `Z`. In the case above, I think we can all probably agree
that it makes the most sense to use the `x2` constructor for `X`,
because `Y`'s `x1` constructor exists "beneath" `Z` in the inheritance
hierarchy; `Z`'s constructor is "more specific".
The algorithm is simple and predictable:
1. Use all of the constructors (including default constructors) directly
defined in the spawned component's require list
2. In the order the requires are defined in `#[require()]`, recursively
visit the require list of each of the components in the list (this is a
depth Depth First Search). When a constructor is found, it will only be
used if one has not already been found.
From a user perspective, just think about this as the following:
1. Specifying a required component constructor for `Foo` directly on a
spawned component `Bar` will result in that constructor being used (and
overriding existing constructors lower in the inheritance tree). This is
the classic "inheritance override" behavior people expect.
2. For cases where "multiple inheritance" results in constructor
clashes, Components should be listed in "importance order". List a
component earlier in the requirement list to initialize its inheritance
tree earlier.
Required Components _does_ generally result in a model where component
values are decoupled from each other at construction time. Notably, some
existing Bundle patterns use bundle constructors to initialize multiple
components with shared state. I think (in general) moving away from this
is necessary:
1. It allows Required Components (and the Scene system more generally)
to operate according to simple rules
2. The "do arbitrary init value sharing in Bundle constructors" approach
_already_ causes data consistency problems, and those problems would be
exacerbated in the context of a Scene/UI system. For cases where shared
state is truly necessary, I think we are better served by observers /
hooks.
3. If a situation _truly_ needs shared state constructors (which should
be rare / generally discouraged), Bundles are still there if they are
needed.
## Next Steps
* **Require Construct-ed Components**: I have already implemented this
(as defined in the [Next Generation Scene / UI
Proposal](https://github.com/bevyengine/bevy/discussions/14437). However
I've removed `Construct` support from this PR, as that has not landed
yet. Adding this back in requires relatively minimal changes to the
current impl, and can be done as part of a future Construct pr.
* **Port Built-in Bundles to Required Components**: This isn't something
we should do right away. It will require rethinking our public
interfaces, which IMO should be done holistically after the rest of Next
Generation Scene / UI lands. I think we should merge this PR first and
let people experiment _inside their own code with their own Components_
while we wait for the rest of the new scene system to land.
* **_Consider_ Automatic Required Component Removal**: We should
evaluate _if_ automatic Required Component removal should be done. Ex:
if all components that explicitly require a component are removed,
automatically remove that component. This issue has been explicitly
deferred in this PR, as I consider the insertion behavior to be
desirable on its own (and viable on its own). I am also doubtful that we
can find a design that has behavior we actually want. Aka: can we
_really_ distinguish between a component that is "only there because it
was automatically inserted" and "a component that was necessary / should
be kept". See my [discussion response
here](https://github.com/bevyengine/bevy/discussions/14437#discussioncomment-10268668)
for more details.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: BD103 <59022059+BD103@users.noreply.github.com>
Co-authored-by: Pascal Hertleif <killercup@gmail.com>
# Objective
Allow dynamic systems to take lists of system parameters whose length is
not known at compile time.
This can be used for building a system that runs a script defined at
runtime, where the script needs a variable number of query parameters.
It can also be used for building a system that collects a list of
plugins at runtime, and provides a parameter to each one.
This is most useful today with `Vec<Query<FilteredEntityMut>>`. It will
be even more useful with `Vec<DynSystemParam>` if #14817 is merged,
since the parameters in the list can then be of different types.
## Solution
Implement `SystemParam` and `SystemParamBuilder` for `Vec` and
`ParamSet<Vec>`.
## Example
```rust
let system = (vec![
QueryParamBuilder::new_box(|builder| {
builder.with::<B>().without::<C>();
}),
QueryParamBuilder::new_box(|builder| {
builder.with::<C>().without::<B>();
}),
],)
.build_state(&mut world)
.build_system(|params: Vec<Query<&mut A>>| {
let mut count: usize = 0;
params
.into_iter()
.for_each(|mut query| count += query.iter_mut().count());
count
});
```
# Objective
Fixes#14883
## Solution
Pretty simple update to `EntityCommands` methods to consume `self` and
return it rather than taking `&mut self`. The things probably worth
noting:
* I added `#[allow(clippy::should_implement_trait)]` to the `add` method
because it causes a linting conflict with `std::ops::Add`.
* `despawn` and `log_components` now return `Self`. I'm not sure if
that's exactly the desired behavior so I'm happy to adjust if that seems
wrong.
## Testing
Tested with `cargo run -p ci`. I think that should be sufficient to call
things good.
## Migration Guide
The most likely migration needed is changing code from this:
```
let mut entity = commands.get_or_spawn(entity);
if depth_prepass {
entity.insert(DepthPrepass);
}
if normal_prepass {
entity.insert(NormalPrepass);
}
if motion_vector_prepass {
entity.insert(MotionVectorPrepass);
}
if deferred_prepass {
entity.insert(DeferredPrepass);
}
```
to this:
```
let mut entity = commands.get_or_spawn(entity);
if depth_prepass {
entity = entity.insert(DepthPrepass);
}
if normal_prepass {
entity = entity.insert(NormalPrepass);
}
if motion_vector_prepass {
entity = entity.insert(MotionVectorPrepass);
}
if deferred_prepass {
entity.insert(DeferredPrepass);
}
```
as can be seen in several of the example code updates here. There will
probably also be instances where mutable `EntityCommands` vars no longer
need to be mutable.
# Objective
Support building systems with parameters whose types can be determined
at runtime.
## Solution
Create a `DynSystemParam` type that can be built using a
`SystemParamBuilder` of any type and then downcast to the appropriate
type dynamically.
## Example
```rust
let system = (
DynParamBuilder::new(LocalBuilder(3_usize)),
DynParamBuilder:🆕:<Query<()>>(QueryParamBuilder::new(|builder| {
builder.with::<A>();
})),
DynParamBuilder:🆕:<&Entities>(ParamBuilder),
)
.build_state(&mut world)
.build_system(
|mut p0: DynSystemParam, mut p1: DynSystemParam, mut p2: DynSystemParam| {
let local = p0.downcast_mut::<Local<usize>>().unwrap();
let query_count = p1.downcast_mut::<Query<()>>().unwrap();
let entities = p2.downcast_mut::<&Entities>().unwrap();
},
);
```
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Periwink <charlesbour@gmail.com>
# Objective
- Fixes#14658.
## Solution
- Added `on_unimplemented` Diagnostic for `IntoObserverSystem` calling
out argument ordering in a `note`
- Added an example to the documentation on `App::observe` to provide
some explanation to users.
## Testing
- Ran CI locally
- Deliberately introduced a parameter order error in the
`ecs/observers.rs` example as a test.
---
## Showcase
<details>
<summary>Error Before</summary>
```
error[E0277]: the trait bound `{closure@examples/ecs/observers.rs:19:13: 22:37}: IntoObserverSystem<_, _, _>` is not satisfied
--> examples/ecs/observers.rs:19:13
|
18 | .observe(
| ------- required by a bound introduced by this call
19 | / |mines: Query<&Mine>,
20 | | trigger: Trigger<ExplodeMines>,
21 | | index: Res<SpatialIndex>,
22 | | mut commands: Commands| {
... |
34 | | }
35 | | },
| |_____________^ the trait `bevy::prelude::IntoSystem<bevy::prelude::Trigger<'static, _, _>, (), _>` is not implemented for closure `{closure@examples/ecs/observers.rs:19:13: 22:37}`, which is required by `{closure@examples/ecs/observers.rs:19:13: 22:37}: IntoObserverSystem<_, _, _>`
|
= note: required for `{closure@examples/ecs/observers.rs:19:13: 22:37}` to implement `IntoObserverSystem<_, _, _>`
note: required by a bound in `bevy::prelude::App::observe`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_app\src\app.rs:995:24
|
993 | pub fn observe<E: Event, B: Bundle, M>(
| ------- required by a bound in this associated function
994 | &mut self,
995 | observer: impl IntoObserverSystem<E, B, M>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `App::observe`
For more information about this error, try `rustc --explain E0277`.
error: could not compile `bevy` (example "observers") due to 1 previous error
```
</details>
<details>
<summary>Error After</summary>
```
error[E0277]: `{closure@examples/ecs/observers.rs:19:13: 22:37}` cannot become an `ObserverSystem`
--> examples/ecs/observers.rs:19:13
|
18 | .observe(
| ------- required by a bound introduced by this call
19 | / |mines: Query<&Mine>,
20 | | trigger: Trigger<ExplodeMines>,
21 | | index: Res<SpatialIndex>,
22 | | mut commands: Commands| {
... |
34 | | }
35 | | },
| |_____________^ the trait `IntoObserverSystem` is not implemented
|
= help: the trait `bevy::prelude::IntoSystem<bevy::prelude::Trigger<'static, _, _>, (), _>` is not implemented for closure `{closure@examples/ecs/observers.rs:19:13: 22:37}`, which is required by `{closure@examples/ecs/observers.rs:19:13: 22:37}: IntoObserverSystem<_, _, _>`
= note: for function `ObserverSystem`s, ensure the first argument is a `Trigger<T>` and any subsequent ones are `SystemParam`
= note: required for `{closure@examples/ecs/observers.rs:19:13: 22:37}` to implement `IntoObserverSystem<_, _, _>`
note: required by a bound in `bevy::prelude::App::observe`
--> C:\Users\Zac\Documents\GitHub\bevy\crates\bevy_app\src\app.rs:1025:24
|
1023 | pub fn observe<E: Event, B: Bundle, M>(
| ------- required by a bound in this associated function
1024 | &mut self,
1025 | observer: impl IntoObserverSystem<E, B, M>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `App::observe`
For more information about this error, try `rustc --explain E0277`.
error: could not compile `bevy` (example "observers") due to 1 previous error
```
</details>
# Objective
`ParamSetBuilder` is supposed to be used as a tuple constructor, but the
field was not marked `pub` so it's not actually usable outside of its
module.
## Solution
Mark the field `pub`.
Realize one advantage of doc tests over unit tests is that they test the
public API.
Add a doc test example that uses the field so that this would have been
caught.
# Objective
Fixes#14782
## Solution
Enable the lint and fix all upcoming hints (`--fix`). Also tried to
figure out the false-positive (see review comment). Maybe split this PR
up into multiple parts where only the last one enables the lint, so some
can already be merged resulting in less many files touched / less
potential for merge conflicts?
Currently, there are some cases where it might be easier to read the
code with the qualifier, so perhaps remove the import of it and adapt
its cases? In the current stage it's just a plain adoption of the
suggestions in order to have a base to discuss.
## Testing
`cargo clippy` and `cargo run -p ci` are happy.
# Objective
When reading the ECS code it is sometimes confusing to understand why we
have 2 accesses, one of ComponentId and one of ArchetypeComponentId
## Solution
Make the usage of these 2 accesses more explicit
---------
Co-authored-by: Pascal Hertleif <killercup@gmail.com>
# Objective
Fixes Commands not being `Send` or `Sync` anymore in 0.14 by
implementing `Send` and `Sync` for `RawCommandQueue`.
## Solution
Reference discussion in
[discord](https://discord.com/channels/691052431525675048/691052431974465548/1259464518539411570).
It seems that in https://github.com/bevyengine/bevy/pull/13249, when
adding a `RawCommandQueue` variant to the `InternalQueue`, the `Send /
Sync` traits were not implemented for it, which bubbled up all the way
to `Commands` not being `Send / Sync` anymore.
I am not very familiar with the ECS internals so I can't say whether the
`RawCommandQueue` is safe to be shared between threads, but I know for
sure that before the linked PR `Commands` were indeed `Send` and `Sync`
so that PR broke "some workflows" (mandatory
[xkcd](https://xkcd.com/1172/)).
## Testing
This PR itself includes a compile test to make sure `Commands` will
implement `Send` and `Sync`. The test itself fails without the
implementation and succeeds with it.
Furthermore, if I cherry pick the test to a previous release (i.e. 0.13)
it indeed succeeds, showing that this is a regression specific to 0.14.
---------
Signed-off-by: Luca Della Vedova <lucadv@intrinsic.ai>
# Objective
Fix#14771 by adding a `try_insert_if_new` method to the
`EntityCommands`
## Solution
This simply calls the `try_insert` function with `InsertMode::Keep`
## Testing
I did not add any test because `EntityCommands::try_insert` does not
seem to be tested either. I can add some if needed.
# Objective
Often there are reasons to insert some components (e.g. Transform)
separately from the rest of a bundle (e.g. PbrBundle). However `insert`
overwrites existing components, making this difficult.
See also issue #14397Fixes#2054.
## Solution
This PR adds the method `insert_if_new` to EntityMut and Commands, which
is the same as `insert` except that the old component is kept in case of
conflicts.
It also renames some internal enums (from `ComponentStatus::Mutated` to
`Existing`), to reflect the possible change in meaning.
## Testing
*Did you test these changes? If so, how?*
Added basic unit tests; used the new behavior in my project.
*Are there any parts that need more testing?*
There should be a test that the change time isn't set if a component is
not overwritten; I wasn't sure how to write a test for that case.
*How can other people (reviewers) test your changes? Is there anything
specific they need to know?*
`cargo test` in the bevy_ecs project.
*If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?*
Only tested on Windows, but it doesn't touch anything platform-specific.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Giacomo Stevanato <giaco.stevanato@gmail.com>
# Objective
- Sometimes some method or function takes an owned `Query`, but we don't
want to give up ours;
- transmuting it technically a solution, but it more costly than
necessary.
- Make query iterators more flexible
- this would allow the equivalent of
`slice::split_first`/`slice::split_first_mut` for query iterators
- helps with requests like #14685
## Solution
- Add a way for reborrowing queries, that is going from a `&'a mut
Query<'w, 's, D, F>` to a `Query<'a, 's, D, F>`:
- this is safe because the original query will be borrowed while the new
query exists and thus no aliased access can happen;
- it's basically the equivalent of going from `&'short mut &'long mut T`
to `&'short mut T` the the compiler automatically implements.
- Add a way for getting the remainder of a query iterator:
- this is interesting also because the original iterator keeps its
position, which was not possible before;
- this in turn requires a way to reborrow query fetches, which I had to
add to `WorldQuery`.
## Showcase
- You can now reborrow a `Query`, getting an equivalent `Query` with a
shorter lifetime. Previously this was possible for read-only queries by
using `Query::to_readonly`, now it's possible for mutable queries too;
- You can now separately iterate over the remainder of `QueryIter`.
## Migration Guide
- `WorldQuery` now has an additional `shrink_fetch` method you have to
implement if you were implementing `WorldQuery` manually.
# Objective
`Res` and `ResMut` perform redundant lookups of the resource storage,
first to initialize the `ArchetypeComponentId` and then to retrieve it.
## Solution
Use the `archetype_component_id` returned from
`initialize_resource_internal` to avoid an extra lookup and `unwrap()`.
# Objective
- Fixes#14697
## Solution
This PR modifies the existing `all_tuples!` macro to optionally accept a
`#[doc(fake_variadic)]` attribute in its input. If the attribute is
present, each invocation of the impl macro gets the correct attributes
(i.e. the first impl receives `#[doc(fake_variadic)]` while the other
impls are hidden using `#[doc(hidden)]`.
Impls for the empty tuple (unit type) are left untouched (that's what
the [standard
library](https://doc.rust-lang.org/std/cmp/trait.PartialEq.html#impl-PartialEq-for-())
and
[serde](https://docs.rs/serde/latest/serde/trait.Serialize.html#impl-Serialize-for-())
do).
To work around https://github.com/rust-lang/cargo/issues/8811 and to get
impls on re-exports to correctly show up as variadic, `--cfg docsrs_dep`
is passed when building the docs for the toplevel `bevy` crate.
`#[doc(fake_variadic)]` only works on tuples and fn pointers, so impls
for structs like `AnyOf<(T1, T2, ..., Tn)>` are unchanged.
## Testing
I built the docs locally using `RUSTDOCFLAGS='--cfg docsrs'
RUSTFLAGS='--cfg docsrs_dep' cargo +nightly doc --no-deps --workspace`
and checked the documentation page of a trait both in its original crate
and the re-exported version in `bevy`.
The description should correctly mention for how many tuple items the
trait is implemented.
I added `rustc-args` for docs.rs to the `bevy` crate, I hope there
aren't any other notable crates that re-export `#[doc(fake_variadic)]`
traits.
---
## Showcase
`bevy_ecs::query::QueryData`:
<img width="1015" alt="Screenshot 2024-08-12 at 16 41 28"
src="https://github.com/user-attachments/assets/d40136ed-6731-475f-91a0-9df255cd24e3">
`bevy::ecs::query::QueryData` (re-export):
<img width="1005" alt="Screenshot 2024-08-12 at 16 42 57"
src="https://github.com/user-attachments/assets/71d44cf0-0ab0-48b0-9a51-5ce332594e12">
## Original Description
<details>
Resolves#14697
Submitting as a draft for now, very WIP.
Unfortunately, the docs don't show the variadics nicely when looking at
reexported items.
For example:
`bevy_ecs::bundle::Bundle` correctly shows the variadic impl:
while `bevy::ecs::bundle::Bundle` (the reexport) shows all the impls
(not good):
Built using `RUSTDOCFLAGS='--cfg docsrs' cargo +nightly doc --workspace
--no-deps` (`--no-deps` because of wgpu-core).
Maybe I missed something or this is a limitation in the *totally not
private* `#[doc(fake_variadic)]` thingy. In any case I desperately need
some sleep now :))
</details>
# Objective
Enables writing queries like `Query<Entity, With<SystemIdMarker>>` to
filter `Entity`s that are, or are not (with `Without`), `SystemId`s.
## Solution
Simple unit struct `SystemIdMarker` added during
`World::register_boxed_system`; `World::remove_system` already despawns
the entity, removing the marker.
## Testing
No tests, but happy to write some with direction.
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Support more kinds of system params in buildable systems, such as a
`ParamSet` or `Vec` containing buildable params or tuples of buildable
params.
## Solution
Replace the `BuildableSystemParam` trait with `SystemParamBuilder` to
make it easier to compose builders. Provide implementations for existing
buildable params, plus tuples, `ParamSet`, and `Vec`.
## Examples
```rust
// ParamSet of tuple:
let system = (ParamSetBuilder((
QueryParamBuilder::new(|builder| { builder.with::<B>(); }),
QueryParamBuilder::new(|builder| { builder.with::<C>(); }),
)),)
.build_state(&mut world)
.build_system(|mut params: ParamSet<(Query<&mut A>, Query<&mut A>)>| {
params.p0().iter().count() + params.p1().iter().count()
});
// ParamSet of Vec:
let system = (ParamSetBuilder(vec![
QueryParamBuilder::new_box(|builder| { builder.with::<B>(); }),
QueryParamBuilder::new_box(|builder| { builder.with::<C>(); }),
]),)
.build_state(&mut world)
.build_system(|mut params: ParamSet<Vec<Query<&mut A>>>| {
let mut count = 0;
params.for_each(|mut query| count += query.iter_mut().count());
count
});
```
## Migration Guide
The API for `SystemBuilder` has changed. Instead of constructing a
builder with a world and then adding params, you first create a tuple of
param builders and then supply the world.
```rust
// Before
let system = SystemBuilder::<()>::new(&mut world)
.local::<u64>()
.builder::<Local<u64>>(|x| *x = 10)
.builder::<Query<&A>>(|builder| { builder.with::<B>(); })
.build(system);
// After
let system = (
ParamBuilder,
LocalBuilder(10),
QueryParamBuilder::new(|builder| { builder.with::<B>(); }),
)
.build_state(&mut world)
.build_system(system);
```
## Possible Future Work
Here are a few possible follow-up changes. I coded them up to prove that
this API can support them, but they aren't necessary for this PR.
* chescock/bevy#1
* chescock/bevy#2
* chescock/bevy#3
# Objective
- Fixes https://github.com/bevyengine/bevy/issues/14575
- There is a soundness issue because we use `conflicts()` to check for
system ambiguities + soundness issues. However since the current
conflicts is a `Vec<T>`, we cannot express conflicts where there is no
specific `ComponentId` at fault. For example `q1: Query<EntityMut>, q2:
Query<EntityMut>`
There was a TODO to handle the `write_all` case but it was never
resolved
## Solution
- Introduce an `AccessConflict` enum that is either a list of specific
ids that are conflicting or `All` if all component ids are conflicting
## Testing
- Introduced a new unit test to check for the `EntityMut` case
## Migration guide
The `get_conflicts` method of `Access` now returns an `AccessConflict`
enum instead of simply a `Vec` of `ComponentId`s that are causing the
access conflict. This can be useful in cases where there are no
particular `ComponentId`s conflicting, but instead **all** of them are;
for example `fn system(q1: Query<EntityMut>, q2: Query<EntityRef>)`
# Objective
- Fix#14629
## Solution
- Make `QueryState::transmute`, `QueryState::transmute_filtered`,
`QueryState::join` and `QueryState::join_filtered` take a `impl
Into<UnsafeWorldCell>` instead of a `&Components` and validate their
`WorldId`
## Migration Guide
- `QueryState::transmute`, `QueryState::transmute_filtered`,
`QueryState::join` and `QueryState::join_filtered` now take a `impl
Into<UnsafeWorldCell>` instead of a `&Components`
---------
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
B0003 indicates that you tried to act upon a nonexistant entity, but
does not mention where the error occured:
```
2024-07-31T15:46:25.954840Z WARN bevy_ecs::world: error[B0003]: Could not despawn entity Entity { index: 4294967295, generation: 1 } because it doesn't exist in this World. See: https://bevyengine.org/learn/errors/b0003
```
## Solution
Include caller location:
```
2024-07-31T15:46:25.954840Z WARN bevy_ecs::world: error[B0003]: src/main.rs:18:11: Could not despawn entity Entity { index: 4294967295, generation: 1 } because it doesn't exist in this World. See: https://bevyengine.org/learn/errors/b0003
```
Open question: What should the exact message format be?
## Testing
None, this doesn't change any logic.
# Objective
- Make it possible to know *what* changed your component or resource.
- Common need when debugging, when you want to know the last code
location that mutated a value in the ECS.
- This feature would be very useful for the editor alongside system
stepping.
## Solution
- Adds the caller location to column data.
- Mutations now `track_caller` all the way up to the public API.
- Commands that invoke these functions immediately call
`Location::caller`, and pass this into the functions, instead of the
functions themselves attempting to get the caller. This would not work
for commands which are deferred, as the commands are executed by the
scheduler, not the user's code.
## Testing
- The `component_change_detection` example now shows where the component
was mutated:
```
2024-07-28T06:57:48.946022Z INFO component_change_detection: Entity { index: 1, generation: 1 }: New value: MyComponent(0.0)
2024-07-28T06:57:49.004371Z INFO component_change_detection: Entity { index: 1, generation: 1 }: New value: MyComponent(1.0)
2024-07-28T06:57:49.012738Z WARN component_change_detection: Change detected!
-> value: Ref(MyComponent(1.0))
-> added: false
-> changed: true
-> changed by: examples/ecs/component_change_detection.rs:36:23
```
- It's also possible to inspect change location from a debugger:
<img width="608" alt="image"
src="https://github.com/user-attachments/assets/c90ecc7a-0462-457a-80ae-42e7f5d346b4">
---
## Changelog
- Added source locations to ECS change detection behind the
`track_change_detection` flag.
## Migration Guide
- Added `changed_by` field to many internal ECS functions used with
change detection when the `track_change_detection` feature flag is
enabled. Use Location::caller() to provide the source of the function
call.
---------
Co-authored-by: BD103 <59022059+BD103@users.noreply.github.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
# Objective
- The implementation of `update_component_access` for `AnyOf`/`Or` is
kinda weird due to special casing the first filter, let's simplify it;
- Fundamentally we want to fold/reduce the various filters using an OR
operation, however in order to do a proper fold we need a neutral
element for the initial accumulator, which for OR is FALSE. However we
didn't have a way to create a `FilteredAccess` value corresponding to
FALSE and thus the only option was reducing, which special cases the
first element as being the initial accumulator.
This is an alternative to https://github.com/bevyengine/bevy/pull/14026
## Solution
- Introduce `FilteredAccess::empty` as a way to create a
`FilteredAccess` corresponding to the logical proposition FALSE;
- Use it as the initial accumulator for the above operations, allowing
to handle all the elements to fold in the same way.
---
## Migration Guide
- The behaviour of `AnyOf<()>` and `Or<()>` has been changed to match no
archetypes rather than all archetypes to naturally match the
corresponding logical operation. Consider replacing them with `()`
instead.
# Objective
- `SystemId`'s `Debug` implementation includes its `entity` field twice.
- This was likely an oversight in #11019, since before that PR the
second field was the `PhantomData` one.
## Solution
- Only include it once
Alternatively, this could be changed to match the struct representation
of `SystemId`, thus instructing the formatter to print a named struct
and including the `PhantomData` field.
# Objective
The method `World::increment_change_tick` currently takes `&self` as the
method receiver, which is semantically strange. Even though the interior
mutability is sound, the existence of this method is strange since we
tend to think of `&World` as being a read-only snapshot of a world, not
an aliasable reference to a world with mutability. For those purposes,
we have `UnsafeWorldCell`.
## Solution
Change the method signature to take `&mut self`. Use exclusive access to
remove the need for atomic adds, which makes the method slightly more
efficient. Redirect users to [`UnsafeWorldCell::increment_change_tick`]
if they need to increment the world's change tick from an aliased
context.
In practice I don't think there will be many breakages, if any. In cases
where you need to call `increment_change_tick`, you usually already have
either `&mut World` or `UnsafeWorldCell`.
---
## Migration Guide
The method `World::increment_change_tick` now requires `&mut self`
instead of `&self`. If you need to call this method but do not have
mutable access to the world, consider using
`world.as_unsafe_world_cell_readonly().increment_change_tick()`, which
does the same thing, but is less efficient than the method on `World`
due to requiring atomic synchronization.
```rust
fn my_system(world: &World) {
// Before
world.increment_change_tick();
// After
world.as_unsafe_world_cell_readonly().increment_change_tick();
}
```
# Objective
When using tracing or
[`bevy_mod_debugdump`](https://github.com/jakobhellermann/bevy_mod_debugdump),
the names of function systems produced by closures are either ambiguous
(like `game::mainapp::{closure}` when tracing) or too long
(`bevy_mod_debugdump` includes full type signature if no name given),
which makes debugging with tracing difficult.
## Solution
Add a function `with_name` to rename a system. The proposed API can be
used in the following way:
```rust
app
.add_systems(Startup, IntoSystem::into_system(|name: SystemName| {
println!("System name: {}", name.name().to_owned());
}).with_name("print_test_system"));
```
## Testing
- There is a test in
`bevy_ecs::system:system_name::test_closure_system_name_regular_param`
# Objective
- Allow queuing insertion of dynamic components to an existing entity
## Solution
- Add `insert_by_id<T: Send + 'static>(commands: &mut EntityCommands,
component_id: ComponentId, value: T)` and the `try_insert_by_id`
counterpart
## Testing
TODO
- Did you test these changes? If so, how?
- Are there any parts that need more testing?
- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
- If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?
## Alternatives
This PR is not feature-complete for dynamic components. In particular,
it
- only supports one component
- only supports adding components with a known, sized type
These were not implemented because doing so would require enhancing
`CommandQueue` to support pushing unsized commands (or equivalently,
pushing commands with a buffer of data). Even so, the cost would not be
transparent compared to the implementation in this PR, which simply
captures the `ComponentId` and `value: T` into the command closure and
can be easily memcpy'ed to the stack during execution. For example, to
efficiently pass `&[ComponentId]` from the caller to the world, we would
need to:
1. Update `CommandQueue.bytes` from `Vec<MaybeUninit<u8>>` to
`Vec<MaybeUninit<usize>>` so that it has the same alignment as
`ComponentId` (which probably needs to be made `#[repr(transparent)]`
too)
2. After pushing the Command metadata, push padding bytes until the vec
len is a multiple of `size_of::<usize>()`
3. Store `components.len()` in the data
4. memcpy the user-provided `&[ComponentId]` to `CommandQueue.bytes`
5. During execution, round up the data pointer behind the `Command` to
skip padding, then cast the pointer and consume it as a `&[ComponentId]`
The effort here seems unnecessarily high, unless someone else has such a
requirement. At least for the use case I am working with, I only need a
single known type, and if we need multiple components, we could always
enhance this function to accept a `[ComponentId; N]`.
I recommend enhancing the `Bundle` API in the long term to achieve this
goal more elegantly.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Felix Rath <felixm.rath@gmail.com>
