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bevy/examples/reflection/reflection.rs

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//! Illustrates how "reflection" works in Bevy.
//!
//! Reflection provides a way to dynamically interact with Rust types, such as accessing fields
//! by their string name. Reflection is a core part of Bevy and enables a number of interesting
//! features (like scenes).
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use bevy::{
prelude::*,
reflect::{
serde::{ReflectDeserializer, ReflectSerializer},
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](https://github.com/bevyengine/bevy/blob/8e3488c88065a94a4f72199587e59341c9b6553d/crates/bevy_reflect/src/reflect.rs#L337-L342) and make `FromReflect` a requirement to improve [`FromReflect` ergonomics](https://github.com/bevyengine/rfcs/pull/59). This is currently not possible because dynamic types cannot sensibly be `FromReflect`. - Since this is an alternative to #5772, #5781 would be made cleaner. --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
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DynamicStruct, PartialReflect,
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},
};
use serde::de::DeserializeSeed;
fn main() {
App::new()
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.add_plugins(DefaultPlugins)
// Bar will be automatically registered as it's a dependency of Foo
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.register_type::<Foo>()
.add_systems(Startup, setup)
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.run();
}
/// Deriving `Reflect` implements the relevant reflection traits. In this case, it implements the
/// `Reflect` trait and the `Struct` trait `derive(Reflect)` assumes that all fields also implement
/// Reflect.
bevy_reflect: `FromReflect` Ergonomics Implementation (#6056) # Objective **This implementation is based on https://github.com/bevyengine/rfcs/pull/59.** --- Resolves #4597 Full details and motivation can be found in the RFC, but here's a brief summary. `FromReflect` is a very powerful and important trait within the reflection API. It allows Dynamic types (e.g., `DynamicList`, etc.) to be formed into Real ones (e.g., `Vec<i32>`, etc.). This mainly comes into play concerning deserialization, where the reflection deserializers both return a `Box<dyn Reflect>` that almost always contain one of these Dynamic representations of a Real type. To convert this to our Real type, we need to use `FromReflect`. It also sneaks up in other ways. For example, it's a required bound for `T` in `Vec<T>` so that `Vec<T>` as a whole can be made `FromReflect`. It's also required by all fields of an enum as it's used as part of the `Reflect::apply` implementation. So in other words, much like `GetTypeRegistration` and `Typed`, it is very much a core reflection trait. The problem is that it is not currently treated like a core trait and is not automatically derived alongside `Reflect`. This makes using it a bit cumbersome and easy to forget. ## Solution Automatically derive `FromReflect` when deriving `Reflect`. Users can then choose to opt-out if needed using the `#[reflect(from_reflect = false)]` attribute. ```rust #[derive(Reflect)] struct Foo; #[derive(Reflect)] #[reflect(from_reflect = false)] struct Bar; fn test<T: FromReflect>(value: T) {} test(Foo); // <-- OK test(Bar); // <-- Panic! Bar does not implement trait `FromReflect` ``` #### `ReflectFromReflect` This PR also automatically adds the `ReflectFromReflect` (introduced in #6245) registration to the derived `GetTypeRegistration` impl— if the type hasn't opted out of `FromReflect` of course. <details> <summary><h4>Improved Deserialization</h4></summary> > **Warning** > This section includes changes that have since been descoped from this PR. They will likely be implemented again in a followup PR. I am mainly leaving these details in for archival purposes, as well as for reference when implementing this logic again. And since we can do all the above, we might as well improve deserialization. We can now choose to deserialize into a Dynamic type or automatically convert it using `FromReflect` under the hood. `[Un]TypedReflectDeserializer::new` will now perform the conversion and return the `Box`'d Real type. `[Un]TypedReflectDeserializer::new_dynamic` will work like what we have now and simply return the `Box`'d Dynamic type. ```rust // Returns the Real type let reflect_deserializer = UntypedReflectDeserializer::new(&registry); let mut deserializer = ron::de::Deserializer::from_str(input)?; let output: SomeStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?; // Returns the Dynamic type let reflect_deserializer = UntypedReflectDeserializer::new_dynamic(&registry); let mut deserializer = ron::de::Deserializer::from_str(input)?; let output: DynamicStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?; ``` </details> --- ## Changelog * `FromReflect` is now automatically derived within the `Reflect` derive macro * This includes auto-registering `ReflectFromReflect` in the derived `GetTypeRegistration` impl * ~~Renamed `TypedReflectDeserializer::new` and `UntypedReflectDeserializer::new` to `TypedReflectDeserializer::new_dynamic` and `UntypedReflectDeserializer::new_dynamic`, respectively~~ **Descoped** * ~~Changed `TypedReflectDeserializer::new` and `UntypedReflectDeserializer::new` to automatically convert the deserialized output using `FromReflect`~~ **Descoped** ## Migration Guide * `FromReflect` is now automatically derived within the `Reflect` derive macro. Items with both derives will need to remove the `FromReflect` one. ```rust // OLD #[derive(Reflect, FromReflect)] struct Foo; // NEW #[derive(Reflect)] struct Foo; ``` If using a manual implementation of `FromReflect` and the `Reflect` derive, users will need to opt-out of the automatic implementation. ```rust // OLD #[derive(Reflect)] struct Foo; impl FromReflect for Foo {/* ... */} // NEW #[derive(Reflect)] #[reflect(from_reflect = false)] struct Foo; impl FromReflect for Foo {/* ... */} ``` <details> <summary><h4>Removed Migrations</h4></summary> > **Warning** > This section includes changes that have since been descoped from this PR. They will likely be implemented again in a followup PR. I am mainly leaving these details in for archival purposes, as well as for reference when implementing this logic again. * The reflect deserializers now perform a `FromReflect` conversion internally. The expected output of `TypedReflectDeserializer::new` and `UntypedReflectDeserializer::new` is no longer a Dynamic (e.g., `DynamicList`), but its Real counterpart (e.g., `Vec<i32>`). ```rust let reflect_deserializer = UntypedReflectDeserializer::new_dynamic(&registry); let mut deserializer = ron::de::Deserializer::from_str(input)?; // OLD let output: DynamicStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?; // NEW let output: SomeStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?; ``` Alternatively, if this behavior isn't desired, use the `TypedReflectDeserializer::new_dynamic` and `UntypedReflectDeserializer::new_dynamic` methods instead: ```rust // OLD let reflect_deserializer = UntypedReflectDeserializer::new(&registry); // NEW let reflect_deserializer = UntypedReflectDeserializer::new_dynamic(&registry); ``` </details> --------- Co-authored-by: Carter Anderson <mcanders1@gmail.com>
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///
/// All fields in a reflected item will need to be `Reflect` as well. You can opt a field out of
/// reflection by using the `#[reflect(ignore)]` attribute.
/// If you choose to ignore a field, you need to let the automatically-derived `FromReflect` implementation
/// how to handle the field.
/// To do this, you can either define a `#[reflect(default = "...")]` attribute on the ignored field, or
/// opt-out of `FromReflect`'s auto-derive using the `#[reflect(from_reflect = false)]` attribute.
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#[derive(Reflect)]
bevy_reflect: `FromReflect` Ergonomics Implementation (#6056) # Objective **This implementation is based on https://github.com/bevyengine/rfcs/pull/59.** --- Resolves #4597 Full details and motivation can be found in the RFC, but here's a brief summary. `FromReflect` is a very powerful and important trait within the reflection API. It allows Dynamic types (e.g., `DynamicList`, etc.) to be formed into Real ones (e.g., `Vec<i32>`, etc.). This mainly comes into play concerning deserialization, where the reflection deserializers both return a `Box<dyn Reflect>` that almost always contain one of these Dynamic representations of a Real type. To convert this to our Real type, we need to use `FromReflect`. It also sneaks up in other ways. For example, it's a required bound for `T` in `Vec<T>` so that `Vec<T>` as a whole can be made `FromReflect`. It's also required by all fields of an enum as it's used as part of the `Reflect::apply` implementation. So in other words, much like `GetTypeRegistration` and `Typed`, it is very much a core reflection trait. The problem is that it is not currently treated like a core trait and is not automatically derived alongside `Reflect`. This makes using it a bit cumbersome and easy to forget. ## Solution Automatically derive `FromReflect` when deriving `Reflect`. Users can then choose to opt-out if needed using the `#[reflect(from_reflect = false)]` attribute. ```rust #[derive(Reflect)] struct Foo; #[derive(Reflect)] #[reflect(from_reflect = false)] struct Bar; fn test<T: FromReflect>(value: T) {} test(Foo); // <-- OK test(Bar); // <-- Panic! Bar does not implement trait `FromReflect` ``` #### `ReflectFromReflect` This PR also automatically adds the `ReflectFromReflect` (introduced in #6245) registration to the derived `GetTypeRegistration` impl— if the type hasn't opted out of `FromReflect` of course. <details> <summary><h4>Improved Deserialization</h4></summary> > **Warning** > This section includes changes that have since been descoped from this PR. They will likely be implemented again in a followup PR. I am mainly leaving these details in for archival purposes, as well as for reference when implementing this logic again. And since we can do all the above, we might as well improve deserialization. We can now choose to deserialize into a Dynamic type or automatically convert it using `FromReflect` under the hood. `[Un]TypedReflectDeserializer::new` will now perform the conversion and return the `Box`'d Real type. `[Un]TypedReflectDeserializer::new_dynamic` will work like what we have now and simply return the `Box`'d Dynamic type. ```rust // Returns the Real type let reflect_deserializer = UntypedReflectDeserializer::new(&registry); let mut deserializer = ron::de::Deserializer::from_str(input)?; let output: SomeStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?; // Returns the Dynamic type let reflect_deserializer = UntypedReflectDeserializer::new_dynamic(&registry); let mut deserializer = ron::de::Deserializer::from_str(input)?; let output: DynamicStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?; ``` </details> --- ## Changelog * `FromReflect` is now automatically derived within the `Reflect` derive macro * This includes auto-registering `ReflectFromReflect` in the derived `GetTypeRegistration` impl * ~~Renamed `TypedReflectDeserializer::new` and `UntypedReflectDeserializer::new` to `TypedReflectDeserializer::new_dynamic` and `UntypedReflectDeserializer::new_dynamic`, respectively~~ **Descoped** * ~~Changed `TypedReflectDeserializer::new` and `UntypedReflectDeserializer::new` to automatically convert the deserialized output using `FromReflect`~~ **Descoped** ## Migration Guide * `FromReflect` is now automatically derived within the `Reflect` derive macro. Items with both derives will need to remove the `FromReflect` one. ```rust // OLD #[derive(Reflect, FromReflect)] struct Foo; // NEW #[derive(Reflect)] struct Foo; ``` If using a manual implementation of `FromReflect` and the `Reflect` derive, users will need to opt-out of the automatic implementation. ```rust // OLD #[derive(Reflect)] struct Foo; impl FromReflect for Foo {/* ... */} // NEW #[derive(Reflect)] #[reflect(from_reflect = false)] struct Foo; impl FromReflect for Foo {/* ... */} ``` <details> <summary><h4>Removed Migrations</h4></summary> > **Warning** > This section includes changes that have since been descoped from this PR. They will likely be implemented again in a followup PR. I am mainly leaving these details in for archival purposes, as well as for reference when implementing this logic again. * The reflect deserializers now perform a `FromReflect` conversion internally. The expected output of `TypedReflectDeserializer::new` and `UntypedReflectDeserializer::new` is no longer a Dynamic (e.g., `DynamicList`), but its Real counterpart (e.g., `Vec<i32>`). ```rust let reflect_deserializer = UntypedReflectDeserializer::new_dynamic(&registry); let mut deserializer = ron::de::Deserializer::from_str(input)?; // OLD let output: DynamicStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?; // NEW let output: SomeStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?; ``` Alternatively, if this behavior isn't desired, use the `TypedReflectDeserializer::new_dynamic` and `UntypedReflectDeserializer::new_dynamic` methods instead: ```rust // OLD let reflect_deserializer = UntypedReflectDeserializer::new(&registry); // NEW let reflect_deserializer = UntypedReflectDeserializer::new_dynamic(&registry); ``` </details> --------- Co-authored-by: Carter Anderson <mcanders1@gmail.com>
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#[reflect(from_reflect = false)]
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pub struct Foo {
a: usize,
nested: Bar,
#[reflect(ignore)]
_ignored: NonReflectedValue,
}
/// This `Bar` type is used in the `nested` field of the `Foo` type. We must derive `Reflect` here
/// too (or ignore it)
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#[derive(Reflect)]
pub struct Bar {
b: usize,
}
bevy_reflect: `FromReflect` Ergonomics Implementation (#6056) # Objective **This implementation is based on https://github.com/bevyengine/rfcs/pull/59.** --- Resolves #4597 Full details and motivation can be found in the RFC, but here's a brief summary. `FromReflect` is a very powerful and important trait within the reflection API. It allows Dynamic types (e.g., `DynamicList`, etc.) to be formed into Real ones (e.g., `Vec<i32>`, etc.). This mainly comes into play concerning deserialization, where the reflection deserializers both return a `Box<dyn Reflect>` that almost always contain one of these Dynamic representations of a Real type. To convert this to our Real type, we need to use `FromReflect`. It also sneaks up in other ways. For example, it's a required bound for `T` in `Vec<T>` so that `Vec<T>` as a whole can be made `FromReflect`. It's also required by all fields of an enum as it's used as part of the `Reflect::apply` implementation. So in other words, much like `GetTypeRegistration` and `Typed`, it is very much a core reflection trait. The problem is that it is not currently treated like a core trait and is not automatically derived alongside `Reflect`. This makes using it a bit cumbersome and easy to forget. ## Solution Automatically derive `FromReflect` when deriving `Reflect`. Users can then choose to opt-out if needed using the `#[reflect(from_reflect = false)]` attribute. ```rust #[derive(Reflect)] struct Foo; #[derive(Reflect)] #[reflect(from_reflect = false)] struct Bar; fn test<T: FromReflect>(value: T) {} test(Foo); // <-- OK test(Bar); // <-- Panic! Bar does not implement trait `FromReflect` ``` #### `ReflectFromReflect` This PR also automatically adds the `ReflectFromReflect` (introduced in #6245) registration to the derived `GetTypeRegistration` impl— if the type hasn't opted out of `FromReflect` of course. <details> <summary><h4>Improved Deserialization</h4></summary> > **Warning** > This section includes changes that have since been descoped from this PR. They will likely be implemented again in a followup PR. I am mainly leaving these details in for archival purposes, as well as for reference when implementing this logic again. And since we can do all the above, we might as well improve deserialization. We can now choose to deserialize into a Dynamic type or automatically convert it using `FromReflect` under the hood. `[Un]TypedReflectDeserializer::new` will now perform the conversion and return the `Box`'d Real type. `[Un]TypedReflectDeserializer::new_dynamic` will work like what we have now and simply return the `Box`'d Dynamic type. ```rust // Returns the Real type let reflect_deserializer = UntypedReflectDeserializer::new(&registry); let mut deserializer = ron::de::Deserializer::from_str(input)?; let output: SomeStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?; // Returns the Dynamic type let reflect_deserializer = UntypedReflectDeserializer::new_dynamic(&registry); let mut deserializer = ron::de::Deserializer::from_str(input)?; let output: DynamicStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?; ``` </details> --- ## Changelog * `FromReflect` is now automatically derived within the `Reflect` derive macro * This includes auto-registering `ReflectFromReflect` in the derived `GetTypeRegistration` impl * ~~Renamed `TypedReflectDeserializer::new` and `UntypedReflectDeserializer::new` to `TypedReflectDeserializer::new_dynamic` and `UntypedReflectDeserializer::new_dynamic`, respectively~~ **Descoped** * ~~Changed `TypedReflectDeserializer::new` and `UntypedReflectDeserializer::new` to automatically convert the deserialized output using `FromReflect`~~ **Descoped** ## Migration Guide * `FromReflect` is now automatically derived within the `Reflect` derive macro. Items with both derives will need to remove the `FromReflect` one. ```rust // OLD #[derive(Reflect, FromReflect)] struct Foo; // NEW #[derive(Reflect)] struct Foo; ``` If using a manual implementation of `FromReflect` and the `Reflect` derive, users will need to opt-out of the automatic implementation. ```rust // OLD #[derive(Reflect)] struct Foo; impl FromReflect for Foo {/* ... */} // NEW #[derive(Reflect)] #[reflect(from_reflect = false)] struct Foo; impl FromReflect for Foo {/* ... */} ``` <details> <summary><h4>Removed Migrations</h4></summary> > **Warning** > This section includes changes that have since been descoped from this PR. They will likely be implemented again in a followup PR. I am mainly leaving these details in for archival purposes, as well as for reference when implementing this logic again. * The reflect deserializers now perform a `FromReflect` conversion internally. The expected output of `TypedReflectDeserializer::new` and `UntypedReflectDeserializer::new` is no longer a Dynamic (e.g., `DynamicList`), but its Real counterpart (e.g., `Vec<i32>`). ```rust let reflect_deserializer = UntypedReflectDeserializer::new_dynamic(&registry); let mut deserializer = ron::de::Deserializer::from_str(input)?; // OLD let output: DynamicStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?; // NEW let output: SomeStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?; ``` Alternatively, if this behavior isn't desired, use the `TypedReflectDeserializer::new_dynamic` and `UntypedReflectDeserializer::new_dynamic` methods instead: ```rust // OLD let reflect_deserializer = UntypedReflectDeserializer::new(&registry); // NEW let reflect_deserializer = UntypedReflectDeserializer::new_dynamic(&registry); ``` </details> --------- Co-authored-by: Carter Anderson <mcanders1@gmail.com>
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#[derive(Default)]
struct NonReflectedValue {
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_a: usize,
}
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>
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fn setup(type_registry: Res<AppTypeRegistry>) {
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let mut value = Foo {
a: 1,
_ignored: NonReflectedValue { _a: 10 },
nested: Bar { b: 8 },
};
// You can set field values like this. The type must match exactly or this will fail.
*value.get_field_mut("a").unwrap() = 2usize;
assert_eq!(value.a, 2);
assert_eq!(*value.get_field::<usize>("a").unwrap(), 2);
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](https://github.com/bevyengine/bevy/blob/8e3488c88065a94a4f72199587e59341c9b6553d/crates/bevy_reflect/src/reflect.rs#L337-L342) and make `FromReflect` a requirement to improve [`FromReflect` ergonomics](https://github.com/bevyengine/rfcs/pull/59). This is currently not possible because dynamic types cannot sensibly be `FromReflect`. - Since this is an alternative to #5772, #5781 would be made cleaner. --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
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// You can also get the `&dyn PartialReflect` value of a field like this
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let field = value.field("a").unwrap();
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](https://github.com/bevyengine/bevy/blob/8e3488c88065a94a4f72199587e59341c9b6553d/crates/bevy_reflect/src/reflect.rs#L337-L342) and make `FromReflect` a requirement to improve [`FromReflect` ergonomics](https://github.com/bevyengine/rfcs/pull/59). This is currently not possible because dynamic types cannot sensibly be `FromReflect`. - Since this is an alternative to #5772, #5781 would be made cleaner. --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
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// But values introspected via `PartialReflect` will not return `dyn Reflect` trait objects
// (even if the containing type does implement `Reflect`), so we need to convert them:
let fully_reflected_field = field.try_as_reflect().unwrap();
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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](https://github.com/bevyengine/bevy/blob/8e3488c88065a94a4f72199587e59341c9b6553d/crates/bevy_reflect/src/reflect.rs#L337-L342) and make `FromReflect` a requirement to improve [`FromReflect` ergonomics](https://github.com/bevyengine/rfcs/pull/59). This is currently not possible because dynamic types cannot sensibly be `FromReflect`. - Since this is an alternative to #5772, #5781 would be made cleaner. --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2024-08-12 17:01:41 +00:00
// Now, you can downcast your `Reflect` value like this:
assert_eq!(*fully_reflected_field.downcast_ref::<usize>().unwrap(), 2);
// For this specific case, we also support the shortcut `try_downcast_ref`:
assert_eq!(*field.try_downcast_ref::<usize>().unwrap(), 2);
// `DynamicStruct` also implements the `Struct` and `Reflect` traits.
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let mut patch = DynamicStruct::default();
patch.insert("a", 4usize);
// You can "apply" Reflect implementations on top of other Reflect implementations.
// This will only set fields with the same name, and it will fail if the types don't match.
// You can use this to "patch" your types with new values.
value.apply(&patch);
assert_eq!(value.a, 4);
let type_registry = type_registry.read();
// By default, all derived `Reflect` types can be Serialized using serde. No need to derive
// Serialize!
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let serializer = ReflectSerializer::new(&value, &type_registry);
let ron_string =
ron::ser::to_string_pretty(&serializer, ron::ser::PrettyConfig::default()).unwrap();
info!("{}\n", ron_string);
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// Dynamic properties can be deserialized
let reflect_deserializer = ReflectDeserializer::new(&type_registry);
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let mut deserializer = ron::de::Deserializer::from_str(&ron_string).unwrap();
let reflect_value = reflect_deserializer.deserialize(&mut deserializer).unwrap();
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](https://github.com/bevyengine/bevy/blob/8e3488c88065a94a4f72199587e59341c9b6553d/crates/bevy_reflect/src/reflect.rs#L337-L342) and make `FromReflect` a requirement to improve [`FromReflect` ergonomics](https://github.com/bevyengine/rfcs/pull/59). This is currently not possible because dynamic types cannot sensibly be `FromReflect`. - Since this is an alternative to #5772, #5781 would be made cleaner. --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
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// Deserializing returns a `Box<dyn PartialReflect>` value.
// Generally, deserializing a value will return the "dynamic" variant of a type.
// For example, deserializing a struct will return the DynamicStruct type.
bevy_reflect: Replace "value" terminology with "opaque" (#15240) # Objective Currently, the term "value" in the context of reflection is a bit overloaded. For one, it can be used synonymously with "data" or "variable". An example sentence would be "this function takes a reflected value". However, it is also used to refer to reflected types which are `ReflectKind::Value`. These types are usually either primitives, opaque types, or types that don't fall into any other `ReflectKind` (or perhaps could, but don't due to some limitation/difficulty). An example sentence would be "this function takes a reflected value type". This makes it difficult to write good documentation or other learning material without causing some amount of confusion to readers. Ideally, we'd be able to move away from the `ReflectKind::Value` usage and come up with a better term. ## Solution This PR replaces the terminology of "value" with "opaque" across `bevy_reflect`. This includes in documentation, type names, variant names, and macros. The term "opaque" was chosen because that's essentially how the type is treated within the reflection API. In other words, its internal structure is hidden. All we can do is work with the type itself. ### Primitives While primitives are not technically opaque types, I think it's still clearer to refer to them as "opaque" rather than keep the confusing "value" terminology. We could consider adding another concept for primitives (e.g. `ReflectKind::Primitive`), but I'm not sure that provides a lot of benefit right now. In most circumstances, they'll be treated just like an opaque type. They would also likely use the same macro (or two copies of the same macro but with different names). ## Testing You can test locally by running: ``` cargo test --package bevy_reflect --all-features ``` --- ## Migration Guide The reflection concept of "value type" has been replaced with a clearer "opaque type". The following renames have been made to account for this: - `ReflectKind::Value` → `ReflectKind::Opaque` - `ReflectRef::Value` → `ReflectRef::Opaque` - `ReflectMut::Value` → `ReflectMut::Opaque` - `ReflectOwned::Value` → `ReflectOwned::Opaque` - `TypeInfo::Value` → `TypeInfo::Opaque` - `ValueInfo` → `OpaqueInfo` - `impl_reflect_value!` → `impl_reflect_opaque!` - `impl_from_reflect_value!` → `impl_from_reflect_opaque!` Additionally, declaring your own opaque types no longer uses `#[reflect_value]`. This attribute has been replaced by `#[reflect(opaque)]`: ```rust // BEFORE #[derive(Reflect)] #[reflect_value(Default)] struct MyOpaqueType(u32); // AFTER #[derive(Reflect)] #[reflect(opaque)] #[reflect(Default)] struct MyOpaqueType(u32); ``` Note that the order in which `#[reflect(opaque)]` appears does not matter.
2024-09-23 18:04:57 +00:00
// "Opaque types" will be deserialized as themselves.
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](https://github.com/bevyengine/bevy/blob/8e3488c88065a94a4f72199587e59341c9b6553d/crates/bevy_reflect/src/reflect.rs#L337-L342) and make `FromReflect` a requirement to improve [`FromReflect` ergonomics](https://github.com/bevyengine/rfcs/pull/59). This is currently not possible because dynamic types cannot sensibly be `FromReflect`. - Since this is an alternative to #5772, #5781 would be made cleaner. --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2024-08-12 17:01:41 +00:00
assert_eq!(
reflect_value.reflect_type_path(),
DynamicStruct::type_path(),
);
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// Reflect has its own `partial_eq` implementation, named `reflect_partial_eq`. This behaves
// like normal `partial_eq`, but it treats "dynamic" and "non-dynamic" types the same. The
// `Foo` struct and deserialized `DynamicStruct` are considered equal for this reason:
assert!(reflect_value.reflect_partial_eq(&value).unwrap());
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// By "patching" `Foo` with the deserialized DynamicStruct, we can "Deserialize" Foo.
// This means we can serialize and deserialize with a single `Reflect` derive!
value.apply(&*reflect_value);
}