bevy/crates
Gino Valente df61117850
bevy_reflect: Function registry (#14098)
# Objective

#13152 added support for reflecting functions. Now, we need a way to
register those functions such that they may be accessed anywhere within
the ECS.

## Solution

Added a `FunctionRegistry` type similar to `TypeRegistry`.

This allows a function to be registered and retrieved by name.

```rust
fn foo() -> i32 {
    123
}

let mut registry = FunctionRegistry::default();
registry.register("my_function", foo);

let function = registry.get_mut("my_function").unwrap();
let value = function.call(ArgList::new()).unwrap().unwrap_owned();
assert_eq!(value.downcast_ref::<i32>(), Some(&123));
```

Additionally, I added an `AppFunctionRegistry` resource which wraps a
`FunctionRegistryArc`. Functions can be registered into this resource
using `App::register_function` or by getting a mutable reference to the
resource itself.

### Limitations

#### `Send + Sync`

In order to get this registry to work across threads, it needs to be
`Send + Sync`. This means that `DynamicFunction` needs to be `Send +
Sync`, which means that its internal function also needs to be `Send +
Sync`.

In most cases, this won't be an issue because standard Rust functions
(the type most likely to be registered) are always `Send + Sync`.
Additionally, closures tend to be `Send + Sync` as well, granted they
don't capture any `!Send` or `!Sync` variables.

This PR adds this `Send + Sync` requirement, but as mentioned above, it
hopefully shouldn't be too big of an issue.

#### Closures

Unfortunately, closures can't be registered yet. This will likely be
explored and added in a followup PR.

### Future Work

Besides addressing the limitations listed above, another thing we could
look into is improving the lookup of registered functions. One aspect is
in the performance of hashing strings. The other is in the developer
experience of having to call `std::any::type_name_of_val` to get the
name of their function (assuming they didn't give it a custom name).

## Testing

You can run the tests locally with:

```
cargo test --package bevy_reflect
```

---

## Changelog

- Added `FunctionRegistry`
- Added `AppFunctionRegistry` (a `Resource` available from `bevy_ecs`)
- Added `FunctionRegistryArc`
- Added `FunctionRegistrationError`
- Added `reflect_functions` feature to `bevy_ecs` and `bevy_app`
- `FunctionInfo` is no longer `Default`
- `DynamicFunction` now requires its wrapped function be `Send + Sync`

## Internal Migration Guide

> [!important]
> Function reflection was introduced as part of the 0.15 dev cycle. This
migration guide was written for developers relying on `main` during this
cycle, and is not a breaking change coming from 0.14.

`DynamicFunction` (both those created manually and those created with
`IntoFunction`), now require `Send + Sync`. All standard Rust functions
should meet that requirement. Closures, on the other hand, may not if
they capture any `!Send` or `!Sync` variables from its environment.
2024-08-06 01:09:48 +00:00
..
bevy_a11y Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_animation Make AnimationPlayer::start and ::play work accordingly to documentation (#14546) 2024-07-31 14:07:53 +00:00
bevy_app bevy_reflect: Function registry (#14098) 2024-08-06 01:09:48 +00:00
bevy_asset Fix common capitalization errors in documentation (#14562) 2024-07-31 21:16:05 +00:00
bevy_audio Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_color Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_core Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_core_pipeline Reflection for DepthOfFieldSettings (#14588) 2024-08-02 15:36:39 +00:00
bevy_derive Remove deprecated bevy_dynamic_plugin (#14534) 2024-07-30 15:31:08 +00:00
bevy_dev_tools Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_diagnostic Add freebsd support for sysinfo (#14553) 2024-07-31 21:41:40 +00:00
bevy_dylib Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_ecs bevy_reflect: Function registry (#14098) 2024-08-06 01:09:48 +00:00
bevy_encase_derive Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_gilrs Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_gizmos Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_gltf Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_hierarchy Add link to with_children in with_child doc (#14604) 2024-08-04 13:36:52 +00:00
bevy_input Fix common capitalization errors in documentation (#14562) 2024-07-31 21:16:05 +00:00
bevy_internal bevy_reflect: Function registry (#14098) 2024-08-06 01:09:48 +00:00
bevy_log Fix common capitalization errors in documentation (#14562) 2024-07-31 21:16:05 +00:00
bevy_macro_utils Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_math Add Dir2::from_xy_unchecked and Dir3::from_xyz_unchecked (#14587) 2024-08-02 13:10:13 +00:00
bevy_mikktspace Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_pbr Don’t prepare lights (and shadow map textures) for 2D cameras (#14574) 2024-08-01 19:29:18 +00:00
bevy_picking Remove manual --cfg docsrs (#14376) 2024-07-22 18:58:04 +00:00
bevy_ptr Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_reflect bevy_reflect: Function registry (#14098) 2024-08-06 01:09:48 +00:00
bevy_render Add depth_ndc_to_view_z for cpu-side (#14590) 2024-08-02 15:37:29 +00:00
bevy_scene Change SceneInstanceReady to trigger an observer. (#13859) 2024-07-30 21:23:48 +00:00
bevy_sprite fix asymmetrical 9-slicing (#14148) 2024-08-01 20:03:23 +00:00
bevy_state Add note on StatesPlugin requirement for state code (#14489) 2024-07-29 23:41:14 +00:00
bevy_tasks Fix common capitalization errors in documentation (#14562) 2024-07-31 21:16:05 +00:00
bevy_text Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_time time_system is ambiguous_with event_update_system (#14544) 2024-07-31 12:13:17 +00:00
bevy_transform Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
bevy_ui Explicitly order CameraUpdateSystem before UiSystem::Prepare (#14609) 2024-08-04 13:34:51 +00:00
bevy_utils update hashbrown to 0.14.2 (#14603) 2024-08-04 13:23:28 +00:00
bevy_window Properly handle repeated window close requests (#14573) 2024-08-01 16:15:28 +00:00
bevy_winit Fix common capitalization errors in documentation (#14562) 2024-07-31 21:16:05 +00:00