# Objective
As work on the editor starts to ramp up, it might be nice to start
allowing types to specify custom attributes. These can be used to
provide certain functionality to fields, such as ranges or controlling
how data is displayed.
A good example of this can be seen in
[`bevy-inspector-egui`](https://github.com/jakobhellermann/bevy-inspector-egui)
with its
[`InspectorOptions`](https://docs.rs/bevy-inspector-egui/0.22.1/bevy_inspector_egui/struct.InspectorOptions.html):
```rust
#[derive(Reflect, Default, InspectorOptions)]
#[reflect(InspectorOptions)]
struct Slider {
#[inspector(min = 0.0, max = 1.0)]
value: f32,
}
```
Normally, as demonstrated in the example above, these attributes are
handled by a derive macro and stored in a corresponding `TypeData`
struct (i.e. `ReflectInspectorOptions`).
Ideally, we would have a good way of defining this directly via
reflection so that users don't need to create and manage a whole proc
macro just to allow these sorts of attributes.
And note that this doesn't have to just be for inspectors and editors.
It can be used for things done purely on the code side of things.
## Solution
Create a new method for storing attributes on fields via the `Reflect`
derive.
These custom attributes are stored in type info (e.g. `NamedField`,
`StructInfo`, etc.).
```rust
#[derive(Reflect)]
struct Slider {
#[reflect(@0.0..=1.0)]
value: f64,
}
let TypeInfo::Struct(info) = Slider::type_info() else {
panic!("expected struct info");
};
let field = info.field("value").unwrap();
let range = field.get_attribute::<RangeInclusive<f64>>().unwrap();
assert_eq!(*range, 0.0..=1.0);
```
## TODO
- [x] ~~Bikeshed syntax~~ Went with a type-based approach, prefixed by
`@` for ease of parsing and flexibility
- [x] Add support for custom struct/tuple struct field attributes
- [x] Add support for custom enum variant field attributes
- [x] ~~Add support for custom enum variant attributes (maybe?)~~ ~~Will
require a larger refactor. Can be saved for a future PR if we really
want it.~~ Actually, we apparently still have support for variant
attributes despite not using them, so it was pretty easy to add lol.
- [x] Add support for custom container attributes
- [x] Allow custom attributes to store any reflectable value (not just
`Lit`)
- [x] ~~Store attributes in registry~~ This PR used to store these in
attributes in the registry, however, it has since switched over to
storing them in type info
- [x] Add example
## Bikeshedding
> [!note]
> This section was made for the old method of handling custom
attributes, which stored them by name (i.e. `some_attribute = 123`). The
PR has shifted away from that, to a more type-safe approach.
>
> This section has been left for reference.
There are a number of ways we can syntactically handle custom
attributes. Feel free to leave a comment on your preferred one! Ideally
we want one that is clear, readable, and concise since these will
potentially see _a lot_ of use.
Below is a small, non-exhaustive list of them. Note that the
`skip_serializing` reflection attribute is added to demonstrate how each
case plays with existing reflection attributes.
<details>
<summary>List</summary>
##### 1. `@(name = value)`
> The `@` was chosen to make them stand out from other attributes and
because the "at" symbol is a subtle pneumonic for "attribute". Of
course, other symbols could be used (e.g. `$`, `#`, etc.).
```rust
#[derive(Reflect)]
struct Slider {
#[reflect(@(min = 0.0, max = 1.0), skip_serializing)]
#[[reflect(@(bevy_editor::hint = "Range: 0.0 to 1.0"))]
value: f32,
}
```
##### 2. `@name = value`
> This is my personal favorite.
```rust
#[derive(Reflect)]
struct Slider {
#[reflect(@min = 0.0, @max = 1.0, skip_serializing)]
#[[reflect(@bevy_editor::hint = "Range: 0.0 to 1.0")]
value: f32,
}
```
##### 3. `custom_attr(name = value)`
> `custom_attr` can be anything. Other possibilities include `with` or
`tag`.
```rust
#[derive(Reflect)]
struct Slider {
#[reflect(custom_attr(min = 0.0, max = 1.0), skip_serializing)]
#[[reflect(custom_attr(bevy_editor::hint = "Range: 0.0 to 1.0"))]
value: f32,
}
```
##### 4. `reflect_attr(name = value)`
```rust
#[derive(Reflect)]
struct Slider {
#[reflect(skip_serializing)]
#[reflect_attr(min = 0.0, max = 1.0)]
#[[reflect_attr(bevy_editor::hint = "Range: 0.0 to 1.0")]
value: f32,
}
```
</details>
---
## Changelog
- Added support for custom attributes on reflected types (i.e.
`#[reflect(@Foo::new("bar")]`)
# Objective
Unblocks #11659.
Currently the `Reflect` derive macro has to go through a merge process
for each `#[reflect]`/`#[reflet_value]` attribute encountered on a
container type.
Not only is this a bit inefficient, but it also has a soft requirement
that we can compare attributes such that an error can be thrown on
duplicates, invalid states, etc.
While working on #11659 this proved to be challenging due to the fact
that `syn` types don't implement `PartialEq` or `Hash` without enabling
the `extra-traits` feature.
Ideally, we wouldn't have to enable another feature just to accommodate
this one use case.
## Solution
Removed `ContainerAttributes::merge`.
This was a fairly simple change as we could just have the parsing
functions take `&mut self` instead of returning `Self`.
## Testing
CI should build as there should be no user-facing change.
# Objective
- Some of the "large" crates have sub-crates, usually for things such as
macros.
- For an example, see [`bevy_ecs_macros` at
`bevy_ecs/macros`](4f9f987099/crates/bevy_ecs/macros).
- The one crate that does not follow this convention is
[`bevy_reflect_derive`](4f9f987099/crates/bevy_reflect/bevy_reflect_derive),
which is in the `bevy_reflect/bevy_reflect_derive` folder and not
`bevy_reflect/derive` or `bevy_reflect/macros`.
## Solution
- Rename folder `bevy_reflect_derive` to `derive`.
- I chose to use `derive` instead of `macros` because the crate name
itself ends in `_derive`. (One of only two crates to actually use this
convention, funnily enough.)
## Testing
- Build and test `bevy_reflect` and `bevy_reflect_derive`.
- Apply the following patch to `publish.sh` to run it in `--dry-run`
mode, to test that the path has been successfully updated:
- If you have any security concerns about applying random diffs, feel
free to skip this step. Worst case scenario it fails and Cart has to
manually publish a few crates.
```bash
# Apply patch to make `publish.sh` *not* actually publish anything.
git apply path/to/foo.patch
# Make `publish.sh` executable.
chmod +x tools/publish.sh
# Execute `publish.sh`.
./tools/publish.sh
```
```patch
diff --git a/tools/publish.sh b/tools/publish.sh
index b020bad28..fbcc09281 100644
--- a/tools/publish.sh
+++ b/tools/publish.sh
@@ -49,7 +49,7 @@ crates=(
if [ -n "$(git status --porcelain)" ]; then
echo "You have local changes!"
- exit 1
+ # exit 1
fi
pushd crates
@@ -61,15 +61,15 @@ do
cp ../LICENSE-APACHE "$crate"
pushd "$crate"
git add LICENSE-MIT LICENSE-APACHE
- cargo publish --no-verify --allow-dirty
+ cargo publish --no-verify --allow-dirty --dry-run
popd
- sleep 20
+ # sleep 20
done
popd
echo "Publishing root crate"
-cargo publish --allow-dirty
+cargo publish --allow-dirty --dry-run
echo "Cleaning local state"
git reset HEAD --hard
```
---
## Changelog
- Moved `bevy_reflect_derive` from
`crates/bevy_reflect/bevy_reflect_derive` to
`crates/bevy_reflect/derive`.
2024-05-07 07:55:32 +00:00
Renamed from crates/bevy_reflect/bevy_reflect_derive/src/derive_data.rs (Browse further)
