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8 commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Gino Valente
|
3892adcb47
|
bevy_reflect: Add Type type (#14838)
# Objective Closes #7622. I was working on adding support for reflecting generic functions and found that I wanted to use an argument's `TypeId` for hashing and comparison, but its `TypePath` for debugging and error messaging. While I could just keep them separate, place them in a tuple or a local struct or something, I think I see an opportunity to make a dedicate type for this. Additionally, we can use this type to clean up some duplication amongst the type info structs in a manner similar to #7622. ## Solution Added the `Type` type. This should be seen as the most basic representation of a type apart from `TypeId`. It stores both the `TypeId` of the type as well as its `TypePathTable`. The `Hash` and `PartialEq` implementations rely on the `TypeId`, while the `Debug` implementation relies on the `TypePath`. This makes it especially useful as a key in a `HashMap` since we get the speed of the `TypeId` hashing/comparisons with the readability of `TypePath`. With this type, we're able to reduce the duplication across the type info structs by removing individual fields for `TypeId` and `TypePathTable`, replacing them with a single `Type` field. Similarly, we can remove many duplicate methods and replace it with a macro that delegates to the stored `Type`. ### Caveats It should be noted that this type is currently 3x larger than `TypeId`. On my machine, it's 48 bytes compared to `TypeId`'s 16. While this doesn't matter for `TypeInfo` since it would contain that data regardless, it is something to keep in mind when using elsewhere. ## Testing All tests should pass as normal: ``` cargo test --package bevy_reflect ``` --- ## Showcase `bevy_reflect` now exports a `Type` struct. This type contains both the `TypeId` and the `TypePathTable` of the given type, allowing it to be used like `TypeId` but have the debuggability of `TypePath`. ```rust // We can create this for any type implementing `TypePath`: let ty = Type::of::<String>(); // It has `Hash` and `Eq` impls powered by `TypeId`, making it useful for maps: let mut map = HashMap::<Type, i32>::new(); map.insert(ty, 25); // And it has a human-readable `Debug` representation: let debug = format!("{:?}", map); assert_eq!(debug, "{alloc::string::String: 25}"); ``` ## Migration Guide Certain type info structs now only return their item types as `Type` instead of exposing direct methods on them. The following methods have been removed: - `ArrayInfo::item_type_path_table` - `ArrayInfo::item_type_id` - `ArrayInfo::item_is` - `ListInfo::item_type_path_table` - `ListInfo::item_type_id` - `ListInfo::item_is` - `SetInfo::value_type_path_table` - `SetInfo::value_type_id` - `SetInfo::value_is` - `MapInfo::key_type_path_table` - `MapInfo::key_type_id` - `MapInfo::key_is` - `MapInfo::value_type_path_table` - `MapInfo::value_type_id` - `MapInfo::value_is` Instead, access the `Type` directly using one of the new methods: - `ArrayInfo::item_ty` - `ListInfo::item_ty` - `SetInfo::value_ty` - `MapInfo::key_ty` - `MapInfo::value_ty` For example: ```rust // BEFORE let type_id = array_info.item_type_id(); // AFTER let type_id = array_info.item_ty().id(); ``` |
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radiish
|
6ab8767d3b
|
reflect: implement the unique reflect rfc (#7207)
# Objective
- Implements the [Unique Reflect
RFC](https://github.com/nicopap/rfcs/blob/bevy-reflect-api/rfcs/56-better-reflect.md).
## Solution
- Implements the RFC.
- This implementation differs in some ways from the RFC:
- In the RFC, it was suggested `Reflect: Any` but `PartialReflect:
?Any`. During initial implementation I tried this, but we assume the
`PartialReflect: 'static` in a lot of places and the changes required
crept out of the scope of this PR.
- `PartialReflect::try_into_reflect` originally returned `Option<Box<dyn
Reflect>>` but i changed this to `Result<Box<dyn Reflect>, Box<dyn
PartialReflect>>` since the method takes by value and otherwise there
would be no way to recover the type. `as_full` and `as_full_mut` both
still return `Option<&(mut) dyn Reflect>`.
---
## Changelog
- Added `PartialReflect`.
- `Reflect` is now a subtrait of `PartialReflect`.
- Moved most methods on `Reflect` to the new `PartialReflect`.
- Added `PartialReflect::{as_partial_reflect, as_partial_reflect_mut,
into_partial_reflect}`.
- Added `PartialReflect::{try_as_reflect, try_as_reflect_mut,
try_into_reflect}`.
- Added `<dyn PartialReflect>::{try_downcast_ref, try_downcast_mut,
try_downcast, try_take}` supplementing the methods on `dyn Reflect`.
## Migration Guide
- Most instances of `dyn Reflect` should be changed to `dyn
PartialReflect` which is less restrictive, however trait bounds should
generally stay as `T: Reflect`.
- The new `PartialReflect::{as_partial_reflect, as_partial_reflect_mut,
into_partial_reflect, try_as_reflect, try_as_reflect_mut,
try_into_reflect}` methods as well as `Reflect::{as_reflect,
as_reflect_mut, into_reflect}` will need to be implemented for manual
implementors of `Reflect`.
## Future Work
- This PR is designed to be followed up by another "Unique Reflect Phase
2" that addresses the following points:
- Investigate making serialization revolve around `Reflect` instead of
`PartialReflect`.
- [Remove the `try_*` methods on `dyn PartialReflect` since they are
stop
gaps](https://github.com/bevyengine/bevy/pull/7207#discussion_r1083476050).
- Investigate usages like `ReflectComponent`. In the places they
currently use `PartialReflect`, should they be changed to use `Reflect`?
- Merging this opens the door to lots of reflection features we haven't
been able to implement.
- We could re-add [the `Reflectable`
trait](
|
||
|
Gino Valente
|
aa241672e1
|
bevy_reflect: Nested TypeInfo getters (#13321)
# Objective
Right now, `TypeInfo` can be accessed directly from a type using either
`Typed::type_info` or `Reflect::get_represented_type_info`.
However, once that `TypeInfo` is accessed, any nested types must be
accessed via the `TypeRegistry`.
```rust
#[derive(Reflect)]
struct Foo {
bar: usize
}
let registry = TypeRegistry::default();
let TypeInfo::Struct(type_info) = Foo::type_info() else {
panic!("expected struct info");
};
let field = type_info.field("bar").unwrap();
let field_info = registry.get_type_info(field.type_id()).unwrap();
assert!(field_info.is::<usize>());;
```
## Solution
Enable nested types within a `TypeInfo` to be retrieved directly.
```rust
#[derive(Reflect)]
struct Foo {
bar: usize
}
let TypeInfo::Struct(type_info) = Foo::type_info() else {
panic!("expected struct info");
};
let field = type_info.field("bar").unwrap();
let field_info = field.type_info().unwrap();
assert!(field_info.is::<usize>());;
```
The particular implementation was chosen for two reasons.
Firstly, we can't just store `TypeInfo` inside another `TypeInfo`
directly. This is because some types are recursive and would result in a
deadlock when trying to create the `TypeInfo` (i.e. it has to create the
`TypeInfo` before it can use it, but it also needs the `TypeInfo` before
it can create it). Therefore, we must instead store the function so it
can be retrieved lazily.
I had considered also using a `OnceLock` or something to lazily cache
the info, but I figured we can look into optimizations later. The API
should remain the same with or without the `OnceLock`.
Secondly, a new wrapper trait had to be introduced: `MaybeTyped`. Like
`RegisterForReflection`, this trait is `#[doc(hidden)]` and only exists
so that we can properly handle dynamic type fields without requiring
them to implement `Typed`. We don't want dynamic types to implement
`Typed` due to the fact that it would make the return type
`Option<&'static TypeInfo>` for all types even though only the dynamic
types ever need to return `None` (see #6971 for details).
Users should never have to interact with this trait as it has a blanket
impl for all `Typed` types. And `Typed` is automatically implemented
when deriving `Reflect` (as it is required).
The one downside is we do need to return `Option<&'static TypeInfo>`
from all these new methods so that we can handle the dynamic cases. If
we didn't have to, we'd be able to get rid of the `Option` entirely. But
I think that's an okay tradeoff for this one part of the API, and keeps
the other APIs intact.
## Testing
This PR contains tests to verify everything works as expected. You can
test locally by running:
```
cargo test --package bevy_reflect
```
---
## Changelog
### Public Changes
- Added `ArrayInfo::item_info` method
- Added `NamedField::type_info` method
- Added `UnnamedField::type_info` method
- Added `ListInfo::item_info` method
- Added `MapInfo::key_info` method
- Added `MapInfo::value_info` method
- All active fields now have a `Typed` bound (remember that this is
automatically satisfied for all types that derive `Reflect`)
### Internal Changes
- Added `MaybeTyped` trait
## Migration Guide
All active fields for reflected types (including lists, maps, tuples,
etc.), must implement `Typed`. For the majority of users this won't have
any visible impact.
However, users implementing `Reflect` manually may need to update their
types to implement `Typed` if they weren't already.
Additionally, custom dynamic types will need to implement the new hidden
`MaybeTyped` trait.
|
||
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Gino Valente
|
5db52663b3
|
bevy_reflect: Custom attributes (#11659)
# 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")]`) |
||
|
radiish
|
262846e702
|
reflect: TypePath part 2 (#8768)
# Objective
- Followup to #7184.
- ~Deprecate `TypeUuid` and remove its internal references.~ No longer
part of this PR.
- Use `TypePath` for the type registry, and (de)serialisation instead of
`std::any::type_name`.
- Allow accessing type path information behind proxies.
## Solution
- Introduce methods on `TypeInfo` and friends for dynamically querying
type path. These methods supersede the old `type_name` methods.
- Remove `Reflect::type_name` in favor of `DynamicTypePath::type_path`
and `TypeInfo::type_path_table`.
- Switch all uses of `std::any::type_name` in reflection, non-debugging
contexts to use `TypePath`.
---
## Changelog
- Added `TypePathTable` for dynamically accessing methods on `TypePath`
through `TypeInfo` and the type registry.
- Removed `type_name` from all `TypeInfo`-like structs.
- Added `type_path` and `type_path_table` methods to all `TypeInfo`-like
structs.
- Removed `Reflect::type_name` in favor of
`DynamicTypePath::reflect_type_path` and `TypeInfo::type_path`.
- Changed the signature of all `DynamicTypePath` methods to return
strings with a static lifetime.
## Migration Guide
- Rely on `TypePath` instead of `std::any::type_name` for all stability
guarantees and for use in all reflection contexts, this is used through
with one of the following APIs:
- `TypePath::type_path` if you have a concrete type and not a value.
- `DynamicTypePath::reflect_type_path` if you have an `dyn Reflect`
value without a concrete type.
- `TypeInfo::type_path` for use through the registry or if you want to
work with the represented type of a `DynamicFoo`.
- Remove `type_name` from manual `Reflect` implementations.
- Use `type_path` and `type_path_table` in place of `type_name` on
`TypeInfo`-like structs.
- Use `get_with_type_path(_mut)` over `get_with_type_name(_mut)`.
## Note to reviewers
I think if anything we were a little overzealous in merging #7184 and we
should take that extra care here.
In my mind, this is the "point of no return" for `TypePath` and while I
think we all agree on the design, we should carefully consider if the
finer details and current implementations are actually how we want them
moving forward.
For example [this incorrect `TypePath` implementation for
`String`](
|
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Gino Valente
|
a658bfef19 |
bevy_reflect: Reflect doc comments (#6234)
# Objective Resolves #6197 Make it so that doc comments can be retrieved via reflection. ## Solution Adds the new `documentation` feature to `bevy_reflect` (disabled by default). When enabled, documentation can be found using `TypeInfo::doc` for reflected types: ```rust /// Some struct. /// /// # Example /// /// ```ignore /// let some_struct = SomeStruct; /// ``` #[derive(Reflect)] struct SomeStruct; let info = <SomeStruct as Typed>::type_info(); assert_eq!( Some(" Some struct.\n\n # Example\n\n ```ignore\n let some_struct = SomeStruct;\n ```"), info.docs() ); ``` ### Notes for Reviewers The bulk of the files simply added the same 16 lines of code (with slightly different documentation). Most of the real changes occur in the `bevy_reflect_derive` files as well as in the added tests. --- ## Changelog * Added `documentation` feature to `bevy_reflect` * Added `TypeInfo::docs` method (and similar methods for all info types) |
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Gino Valente
|
d30d3e752a |
bevy_reflect: Improve serialization format even more (#5723)
> Note: This is rebased off #4561 and can be viewed as a competitor to that PR. See `Comparison with #4561` section for details. # Objective The current serialization format used by `bevy_reflect` is both verbose and error-prone. Taking the following structs[^1] for example: ```rust // -- src/inventory.rs #[derive(Reflect)] struct Inventory { id: String, max_storage: usize, items: Vec<Item> } #[derive(Reflect)] struct Item { name: String } ``` Given an inventory of a single item, this would serialize to something like: ```rust // -- assets/inventory.ron { "type": "my_game::inventory::Inventory", "struct": { "id": { "type": "alloc::string::String", "value": "inv001", }, "max_storage": { "type": "usize", "value": 10 }, "items": { "type": "alloc::vec::Vec<alloc::string::String>", "list": [ { "type": "my_game::inventory::Item", "struct": { "name": { "type": "alloc::string::String", "value": "Pickaxe" }, }, }, ], }, }, } ``` Aside from being really long and difficult to read, it also has a few "gotchas" that users need to be aware of if they want to edit the file manually. A major one is the requirement that you use the proper keys for a given type. For structs, you need `"struct"`. For lists, `"list"`. For tuple structs, `"tuple_struct"`. And so on. It also ***requires*** that the `"type"` entry come before the actual data. Despite being a map— which in programming is almost always orderless by default— the entries need to be in a particular order. Failure to follow the ordering convention results in a failure to deserialize the data. This makes it very prone to errors and annoyances. ## Solution Using #4042, we can remove a lot of the boilerplate and metadata needed by this older system. Since we now have static access to type information, we can simplify our serialized data to look like: ```rust // -- assets/inventory.ron { "my_game::inventory::Inventory": ( id: "inv001", max_storage: 10, items: [ ( name: "Pickaxe" ), ], ), } ``` This is much more digestible and a lot less error-prone (no more key requirements and no more extra type names). Additionally, it is a lot more familiar to users as it follows conventional serde mechanics. For example, the struct is represented with `(...)` when serialized to RON. #### Custom Serialization Additionally, this PR adds the opt-in ability to specify a custom serde implementation to be used rather than the one created via reflection. For example[^1]: ```rust // -- src/inventory.rs #[derive(Reflect, Serialize)] #[reflect(Serialize)] struct Item { #[serde(alias = "id")] name: String } ``` ```rust // -- assets/inventory.ron { "my_game::inventory::Inventory": ( id: "inv001", max_storage: 10, items: [ ( id: "Pickaxe" ), ], ), }, ``` By allowing users to define their own serialization methods, we do two things: 1. We give more control over how data is serialized/deserialized to the end user 2. We avoid having to re-define serde's attributes and forcing users to apply both (e.g. we don't need a `#[reflect(alias)]` attribute). ### Improved Formats One of the improvements this PR provides is the ability to represent data in ways that are more conventional and/or familiar to users. Many users are familiar with RON so here are some of the ways we can now represent data in RON: ###### Structs ```js { "my_crate::Foo": ( bar: 123 ) } // OR { "my_crate::Foo": Foo( bar: 123 ) } ``` <details> <summary>Old Format</summary> ```js { "type": "my_crate::Foo", "struct": { "bar": { "type": "usize", "value": 123 } } } ``` </details> ###### Tuples ```js { "(f32, f32)": (1.0, 2.0) } ``` <details> <summary>Old Format</summary> ```js { "type": "(f32, f32)", "tuple": [ { "type": "f32", "value": 1.0 }, { "type": "f32", "value": 2.0 } ] } ``` </details> ###### Tuple Structs ```js { "my_crate::Bar": ("Hello World!") } // OR { "my_crate::Bar": Bar("Hello World!") } ``` <details> <summary>Old Format</summary> ```js { "type": "my_crate::Bar", "tuple_struct": [ { "type": "alloc::string::String", "value": "Hello World!" } ] } ``` </details> ###### Arrays It may be a bit surprising to some, but arrays now also use the tuple format. This is because they essentially _are_ tuples (a sequence of values with a fixed size), but only allow for homogenous types. Additionally, this is how RON handles them and is probably a result of the 32-capacity limit imposed on them (both by [serde](https://docs.rs/serde/latest/serde/trait.Serialize.html#impl-Serialize-for-%5BT%3B%2032%5D) and by [bevy_reflect](https://docs.rs/bevy/latest/bevy/reflect/trait.GetTypeRegistration.html#impl-GetTypeRegistration-for-%5BT%3B%2032%5D)). ```js { "[i32; 3]": (1, 2, 3) } ``` <details> <summary>Old Format</summary> ```js { "type": "[i32; 3]", "array": [ { "type": "i32", "value": 1 }, { "type": "i32", "value": 2 }, { "type": "i32", "value": 3 } ] } ``` </details> ###### Enums To make things simple, I'll just put a struct variant here, but the style applies to all variant types: ```js { "my_crate::ItemType": Consumable( name: "Healing potion" ) } ``` <details> <summary>Old Format</summary> ```js { "type": "my_crate::ItemType", "enum": { "variant": "Consumable", "struct": { "name": { "type": "alloc::string::String", "value": "Healing potion" } } } } ``` </details> ### Comparison with #4561 This PR is a rebased version of #4561. The reason for the split between the two is because this PR creates a _very_ different scene format. You may notice that the PR descriptions for either PR are pretty similar. This was done to better convey the changes depending on which (if any) gets merged first. If #4561 makes it in first, I will update this PR description accordingly. --- ## Changelog * Re-worked serialization/deserialization for reflected types * Added `TypedReflectDeserializer` for deserializing data with known `TypeInfo` * Renamed `ReflectDeserializer` to `UntypedReflectDeserializer` * ~~Replaced usages of `deserialize_any` with `deserialize_map` for non-self-describing formats~~ Reverted this change since there are still some issues that need to be sorted out (in a separate PR). By reverting this, crates like `bincode` can throw an error when attempting to deserialize non-self-describing formats (`bincode` results in `DeserializeAnyNotSupported`) * Structs, tuples, tuple structs, arrays, and enums are now all de/serialized using conventional serde methods ## Migration Guide * This PR reduces the verbosity of the scene format. Scenes will need to be updated accordingly: ```js // Old format { "type": "my_game::item::Item", "struct": { "id": { "type": "alloc::string::String", "value": "bevycraft:stone", }, "tags": { "type": "alloc::vec::Vec<alloc::string::String>", "list": [ { "type": "alloc::string::String", "value": "material" }, ], }, } // New format { "my_game::item::Item": ( id: "bevycraft:stone", tags: ["material"] ) } ``` [^1]: Some derives omitted for brevity. |
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Gino Valente
|
e6f34ba47f |
bevy_reflect: Add statically available type info for reflected types (#4042)
# Objective > Resolves #4504 It can be helpful to have access to type information without requiring an instance of that type. Especially for `Reflect`, a lot of the gathered type information is known at compile-time and should not necessarily require an instance. ## Solution Created a dedicated `TypeInfo` enum to store static type information. All types that derive `Reflect` now also implement the newly created `Typed` trait: ```rust pub trait Typed: Reflect { fn type_info() -> &'static TypeInfo; } ``` > Note: This trait was made separate from `Reflect` due to `Sized` restrictions. If you only have access to a `dyn Reflect`, just call `.get_type_info()` on it. This new trait method on `Reflect` should return the same value as if you had called it statically. If all you have is a `TypeId` or type name, you can get the `TypeInfo` directly from the registry using the `TypeRegistry::get_type_info` method (assuming it was registered). ### Usage Below is an example of working with `TypeInfo`. As you can see, we don't have to generate an instance of `MyTupleStruct` in order to get this information. ```rust #[derive(Reflect)] struct MyTupleStruct(usize, i32, MyStruct); let info = MyTupleStruct::type_info(); if let TypeInfo::TupleStruct(info) = info { assert!(info.is::<MyTupleStruct>()); assert_eq!(std::any::type_name::<MyTupleStruct>(), info.type_name()); assert!(info.field_at(1).unwrap().is::<i32>()); } else { panic!("Expected `TypeInfo::TupleStruct`"); } ``` ### Manual Implementations It's not recommended to manually implement `Typed` yourself, but if you must, you can use the `TypeInfoCell` to automatically create and manage the static `TypeInfo`s for you (which is very helpful for blanket/generic impls): ```rust use bevy_reflect::{Reflect, TupleStructInfo, TypeInfo, UnnamedField}; use bevy_reflect::utility::TypeInfoCell; struct Foo<T: Reflect>(T); impl<T: Reflect> Typed for Foo<T> { fn type_info() -> &'static TypeInfo { static CELL: TypeInfoCell = TypeInfoCell::generic(); CELL.get_or_insert::<Self, _>(|| { let fields = [UnnamedField:🆕:<T>()]; let info = TupleStructInfo:🆕:<Self>(&fields); TypeInfo::TupleStruct(info) }) } } ``` ## Benefits One major benefit is that this opens the door to other serialization methods. Since we can get all the type info at compile time, we can know how to properly deserialize something like: ```rust #[derive(Reflect)] struct MyType { foo: usize, bar: Vec<String> } // RON to be deserialized: ( type: "my_crate::MyType", // <- We now know how to deserialize the rest of this object value: { // "foo" is a value type matching "usize" "foo": 123, // "bar" is a list type matching "Vec<String>" with item type "String" "bar": ["a", "b", "c"] } ) ``` Not only is this more compact, but it has better compatibility (we can change the type of `"foo"` to `i32` without having to update our serialized data). Of course, serialization/deserialization strategies like this may need to be discussed and fully considered before possibly making a change. However, we will be better equipped to do that now that we can access type information right from the registry. ## Discussion Some items to discuss: 1. Duplication. There's a bit of overlap with the existing traits/structs since they require an instance of the type while the type info structs do not (for example, `Struct::field_at(&self, index: usize)` and `StructInfo::field_at(&self, index: usize)`, though only `StructInfo` is accessible without an instance object). Is this okay, or do we want to handle it in another way? 2. Should `TypeInfo::Dynamic` be removed? Since the dynamic types don't have type information available at runtime, we could consider them `TypeInfo::Value`s (or just even just `TypeInfo::Struct`). The intention with `TypeInfo::Dynamic` was to keep the distinction from these dynamic types and actual structs/values since users might incorrectly believe the methods of the dynamic type's info struct would map to some contained data (which isn't possible statically). 4. General usefulness of this change, including missing/unnecessary parts. 5. Possible changes to the scene format? (One possible issue with changing it like in the example above might be that we'd have to be careful when handling generic or trait object types.) ## Compile Tests I ran a few tests to compare compile times (as suggested [here](https://github.com/bevyengine/bevy/pull/4042#discussion_r876408143)). I toggled `Reflect` and `FromReflect` derive macros using `cfg_attr` for both this PR ( |