bevy/examples/ecs
ira 992681b59b Make Resource trait opt-in, requiring #[derive(Resource)] V2 (#5577)
*This PR description is an edited copy of #5007, written by @alice-i-cecile.*
# Objective
Follow-up to https://github.com/bevyengine/bevy/pull/2254. The `Resource` trait currently has a blanket implementation for all types that meet its bounds.

While ergonomic, this results in several drawbacks:

* it is possible to make confusing, silent mistakes such as inserting a function pointer (Foo) rather than a value (Foo::Bar) as a resource
* it is challenging to discover if a type is intended to be used as a resource
* we cannot later add customization options (see the [RFC](https://github.com/bevyengine/rfcs/blob/main/rfcs/27-derive-component.md) for the equivalent choice for Component).
* dependencies can use the same Rust type as a resource in invisibly conflicting ways
* raw Rust types used as resources cannot preserve privacy appropriately, as anyone able to access that type can read and write to internal values
* we cannot capture a definitive list of possible resources to display to users in an editor
## Notes to reviewers
 * Review this commit-by-commit; there's effectively no back-tracking and there's a lot of churn in some of these commits.
   *ira: My commits are not as well organized :')*
 * I've relaxed the bound on Local to Send + Sync + 'static: I don't think these concerns apply there, so this can keep things simple. Storing e.g. a u32 in a Local is fine, because there's a variable name attached explaining what it does.
 * I think this is a bad place for the Resource trait to live, but I've left it in place to make reviewing easier. IMO that's best tackled with https://github.com/bevyengine/bevy/issues/4981.

## Changelog
`Resource` is no longer automatically implemented for all matching types. Instead, use the new `#[derive(Resource)]` macro.

## Migration Guide
Add `#[derive(Resource)]` to all types you are using as a resource.

If you are using a third party type as a resource, wrap it in a tuple struct to bypass orphan rules. Consider deriving `Deref` and `DerefMut` to improve ergonomics.

`ClearColor` no longer implements `Component`. Using `ClearColor` as a component in 0.8 did nothing.
Use the `ClearColorConfig` in the `Camera3d` and `Camera2d` components instead.


Co-authored-by: Alice <alice.i.cecile@gmail.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: devil-ira <justthecooldude@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2022-08-08 21:36:35 +00:00
..
component_change_detection.rs Update codebase to use IntoIterator where possible. (#5269) 2022-07-11 15:28:50 +00:00
custom_query_param.rs Update codebase to use IntoIterator where possible. (#5269) 2022-07-11 15:28:50 +00:00
ecs_guide.rs Make Resource trait opt-in, requiring #[derive(Resource)] V2 (#5577) 2022-08-08 21:36:35 +00:00
event.rs Make Resource trait opt-in, requiring #[derive(Resource)] V2 (#5577) 2022-08-08 21:36:35 +00:00
fixed_timestep.rs Split time functionality into bevy_time (#4187) 2022-05-26 00:27:18 +00:00
generic_system.rs Update codebase to use IntoIterator where possible. (#5269) 2022-07-11 15:28:50 +00:00
hierarchy.rs Update codebase to use IntoIterator where possible. (#5269) 2022-07-11 15:28:50 +00:00
iter_combinations.rs Use Affine3A for GlobalTransform to allow any affine transformation (#4379) 2022-07-16 00:51:12 +00:00
parallel_query.rs Camera Driven Rendering (#4745) 2022-06-02 00:12:17 +00:00
removal_detection.rs Camera Driven Rendering (#4745) 2022-06-02 00:12:17 +00:00
startup_system.rs Doc/module style doc blocks for examples (#4438) 2022-05-16 13:53:20 +00:00
state.rs Make Resource trait opt-in, requiring #[derive(Resource)] V2 (#5577) 2022-08-08 21:36:35 +00:00
system_chaining.rs Make Resource trait opt-in, requiring #[derive(Resource)] V2 (#5577) 2022-08-08 21:36:35 +00:00
system_closure.rs Doc/module style doc blocks for examples (#4438) 2022-05-16 13:53:20 +00:00
system_param.rs Make Resource trait opt-in, requiring #[derive(Resource)] V2 (#5577) 2022-08-08 21:36:35 +00:00
system_sets.rs Make Resource trait opt-in, requiring #[derive(Resource)] V2 (#5577) 2022-08-08 21:36:35 +00:00
timers.rs Make Resource trait opt-in, requiring #[derive(Resource)] V2 (#5577) 2022-08-08 21:36:35 +00:00