bevy/crates/bevy_reflect/src/array.rs

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bevy_reflect: Better proxies (#6971) # Objective > This PR is based on discussion from #6601 The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as both: 1. Dynamic containers which may hold any arbitrary data 2. Proxy types which may represent any other type Currently, the only way we can represent the proxy-ness of a Dynamic is by giving it a name. ```rust // This is just a dynamic container let mut data = DynamicStruct::default(); // This is a "proxy" data.set_name(std::any::type_name::<Foo>()); ``` This type name is the only way we check that the given Dynamic is a proxy of some other type. When we need to "assert the type" of a `dyn Reflect`, we call `Reflect::type_name` on it. However, because we're only using a string to denote the type, we run into a few gotchas and limitations. For example, hashing a Dynamic proxy may work differently than the type it proxies: ```rust #[derive(Reflect, Hash)] #[reflect(Hash)] struct Foo(i32); let concrete = Foo(123); let dynamic = concrete.clone_dynamic(); let concrete_hash = concrete.reflect_hash(); let dynamic_hash = dynamic.reflect_hash(); // The hashes are not equal because `concrete` uses its own `Hash` impl // while `dynamic` uses a reflection-based hashing algorithm assert_ne!(concrete_hash, dynamic_hash); ``` Because the Dynamic proxy only knows about the name of the type, it's unaware of any other information about it. This means it also differs on `Reflect::reflect_partial_eq`, and may include ignored or skipped fields in places the concrete type wouldn't. ## Solution Rather than having Dynamics pass along just the type name of proxied types, we can instead have them pass around the `TypeInfo`. Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than a `String`: ```diff pub struct DynamicTupleStruct { - type_name: String, + represented_type: Option<&'static TypeInfo>, fields: Vec<Box<dyn Reflect>>, } ``` By changing `Reflect::get_type_info` to `Reflect::represented_type_info`, hopefully we make this behavior a little clearer. And to account for `None` values on these dynamic types, `Reflect::represented_type_info` now returns `Option<&'static TypeInfo>`. ```rust let mut data = DynamicTupleStruct::default(); // Not proxying any specific type assert!(dyn_tuple_struct.represented_type_info().is_none()); let type_info = <Foo as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); // Alternatively: // let dyn_tuple_struct = foo.clone_dynamic(); // Now we're proxying `Foo` assert!(dyn_tuple_struct.represented_type_info().is_some()); ``` This means that we can have full access to all the static type information for the proxied type. Future work would include transitioning more static type information (trait impls, attributes, etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic proxies. ### Alternatives & Rationale > **Note** > These alternatives were written when this PR was first made using a `Proxy` trait. This trait has since been removed. <details> <summary>View</summary> #### Alternative: The `Proxy<T>` Approach I had considered adding something like a `Proxy<T>` type where `T` would be the Dynamic and would contain the proxied type information. This was nice in that it allows us to explicitly determine whether something is a proxy or not at a type level. `Proxy<DynamicStruct>` proxies a struct. Makes sense. The reason I didn't go with this approach is because (1) tuples, (2) complexity, and (3) `PartialReflect`. The `DynamicTuple` struct allows us to represent tuples at runtime. It also allows us to do something you normally can't with tuples: add new fields. Because of this, adding a field immediately invalidates the proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32, NewField)`). By going with this PR's approach, we can just remove the type info on `DynamicTuple` when that happens. However, with the `Proxy<T>` approach, it becomes difficult to represent this behavior— we'd have to completely control how we access data for `T` for each `T`. Secondly, it introduces some added complexities (aside from the manual impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we want to represent it as `dyn Reflect`. What `TypeInfo` do we give it? How would we forward reflection methods to the inner type (remember, we don't have specialization)? How do we separate this from Dynamic types? And finally, how do all this in a way that's both logical and intuitive for users? Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is actually more inline with the [Unique Reflect RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy` trait is really one part of the `PartialReflect` trait introduced in that RFC (it's technically not in that RFC but it fits well with it), where the `PartialReflect` serves as a way for proxies to work _like_ concrete types without having full access to everything a concrete `Reflect` type can do. This would help bridge the gap between the current state of the crate and the implementation of that RFC. All that said, this is still a viable solution. If the community believes this is the better path forward, then we can do that instead. These were just my reasons for not initially going with it in this PR. #### Alternative: The Type Registry Approach The `Proxy` trait is great and all, but how does it solve the original problem? Well, it doesn't— yet! The goal would be to start moving information from the derive macro and its attributes to the generated `TypeInfo` since these are known statically and shouldn't change. For example, adding `ignored: bool` to `[Un]NamedField` or a list of impls. However, there is another way of storing this information. This is, of course, one of the uses of the `TypeRegistry`. If we're worried about Dynamic proxies not aligning with their concrete counterparts, we could move more type information to the registry and require its usage. For example, we could replace `Reflect::reflect_hash(&self)` with `Reflect::reflect_hash(&self, registry: &TypeRegistry)`. That's not the _worst_ thing in the world, but it is an ergonomics loss. Additionally, other attributes may have their own requirements, further restricting what's possible without the registry. The `Reflect::apply` method will require the registry as well now. Why? Well because the `map_apply` function used for the `Reflect::apply` impls on `Map` types depends on `Map::insert_boxed`, which (at least for `DynamicMap`) requires `Reflect::reflect_hash`. The same would apply when adding support for reflection-based diffing, which will require `Reflect::reflect_partial_eq`. Again, this is a totally viable alternative. I just chose not to go with it for the reasons above. If we want to go with it, then we can close this PR and we can pursue this alternative instead. #### Downsides Just to highlight a quick potential downside (likely needs more investigation): retrieving the `TypeInfo` requires acquiring a lock on the `GenericTypeInfoCell` used by the `Typed` impls for generic types (non-generic types use a `OnceBox which should be faster). I am not sure how much of a performance hit that is and will need to run some benchmarks to compare against. </details> ### Open Questions 1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be easier for modding? Perhaps, in that case, we need to update `Typed::type_info` and friends as well? 2. Are the alternatives better than the approach this PR takes? Are there other alternatives? --- ## Changelog ### Changed - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` - This method now returns `Option<&'static TypeInfo>` rather than just `&'static TypeInfo` ### Added - Added `Reflect::is_dynamic` method to indicate when a type is dynamic - Added a `set_represented_type` method on all dynamic types ### Removed - Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead) - Removed `Typed` impls for all dynamic types ## Migration Guide - The Dynamic types no longer take a string type name. Instead, they require a static reference to `TypeInfo`: ```rust #[derive(Reflect)] struct MyTupleStruct(f32, f32); let mut dyn_tuple_struct = DynamicTupleStruct::default(); dyn_tuple_struct.insert(1.23_f32); dyn_tuple_struct.insert(3.21_f32); // BEFORE: let type_name = std::any::type_name::<MyTupleStruct>(); dyn_tuple_struct.set_name(type_name); // AFTER: let type_info = <MyTupleStruct as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); ``` - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` and now also returns an `Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`): ```rust // BEFORE: let info: &'static TypeInfo = value.get_type_info(); // AFTER: let info: &'static TypeInfo = value.represented_type_info().unwrap(); ``` - `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use `Reflect::is_dynamic` instead: ```rust // BEFORE: if matches!(value.get_type_info(), TypeInfo::Dynamic) { // ... } // AFTER: if value.is_dynamic() { // ... } ``` --------- Co-authored-by: radiish <cb.setho@gmail.com>
2023-04-26 12:17:46 +00:00
use crate::{utility::reflect_hasher, Reflect, ReflectMut, ReflectOwned, ReflectRef, TypeInfo};
use std::{
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::new::<T>()]; let info = TupleStructInfo::new::<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 (aa5178e7736a6f8252e10e543e52722107649d3f) and main (c309acd4322b1c3b2089e247a2d28b938eb7b56d). <details> <summary>See More</summary> The test project included 250 of the following structs (as well as a few other structs): ```rust #[derive(Default)] #[cfg_attr(feature = "reflect", derive(Reflect))] #[cfg_attr(feature = "from_reflect", derive(FromReflect))] pub struct Big001 { inventory: Inventory, foo: usize, bar: String, baz: ItemDescriptor, items: [Item; 20], hello: Option<String>, world: HashMap<i32, String>, okay: (isize, usize, /* wesize */), nope: ((String, String), (f32, f32)), blah: Cow<'static, str>, } ``` > I don't know if the compiler can optimize all these duplicate structs away, but I think it's fine either way. We're comparing times, not finding the absolute worst-case time. I only ran each build 3 times using `cargo build --timings` (thank you @devil-ira), each of which were preceeded by a `cargo clean --package bevy_reflect_compile_test`. Here are the times I got: | Test | Test 1 | Test 2 | Test 3 | Average | | -------------------------------- | ------ | ------ | ------ | ------- | | Main | 1.7s | 3.1s | 1.9s | 2.33s | | Main + `Reflect` | 8.3s | 8.6s | 8.1s | 8.33s | | Main + `Reflect` + `FromReflect` | 11.6s | 11.8s | 13.8s | 12.4s | | PR | 3.5s | 1.8s | 1.9s | 2.4s | | PR + `Reflect` | 9.2s | 8.8s | 9.3s | 9.1s | | PR + `Reflect` + `FromReflect` | 12.9s | 12.3s | 12.5s | 12.56s | </details> --- ## Future Work Even though everything could probably be made `const`, we unfortunately can't. This is because `TypeId::of::<T>()` is not yet `const` (see https://github.com/rust-lang/rust/issues/77125). When it does get stabilized, it would probably be worth coming back and making things `const`. Co-authored-by: MrGVSV <49806985+MrGVSV@users.noreply.github.com>
2022-06-09 21:18:15 +00:00
any::{Any, TypeId},
fmt::Debug,
hash::{Hash, Hasher},
};
bevy_reflect: Improved documentation (#7148) # Objective `bevy_reflect` can be a moderately complex crate to try and understand. It has many moving parts, a handful of gotchas, and a few subtle contracts that aren't immediately obvious to users and even other contributors. The current README does an okay job demonstrating how the crate can be used. However, the crate's actual documentation should give a better overview of the crate, its inner-workings, and show some of its own examples. ## Solution Added crate-level documentation that attempts to summarize the main parts of `bevy_reflect` into small sections. This PR also updates the documentation for: - `Reflect` - `FromReflect` - The reflection subtraits - Other important types and traits - The reflection macros (including the derive macros) - Crate features ### Open Questions 1. ~~Should I update the docs for the Dynamic types? I was originally going to, but I'm getting a little concerned about the size of this PR 😅~~ Decided to not do this in this PR. It'll be better served from its own PR. 2. Should derive macro documentation be moved to the trait itself? This could improve visibility and allow for better doc links, but could also clutter up the trait's documentation (as well as not being on the actual derive macro's documentation). ### TODO - [ ] ~~Document Dynamic types (?)~~ I think this should be done in a separate PR. - [x] Document crate features - [x] Update docs for `GetTypeRegistration` - [x] Update docs for `TypeRegistration` - [x] Update docs for `derive_from_reflect` - [x] Document `reflect_trait` - [x] Document `impl_reflect_value` - [x] Document `impl_from_reflect_value` --- ## Changelog - Updated documentation across the `bevy_reflect` crate - Removed `#[module]` helper attribute for `Reflect` derives (this is not currently used) ## Migration Guide - Removed `#[module]` helper attribute for `Reflect` derives. If your code is relying on this attribute, please replace it with either `#[reflect]` or `#[reflect_value]` (dependent on use-case). Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2023-02-18 20:42:01 +00:00
/// A trait used to power [array-like] operations via [reflection].
///
bevy_reflect: Improved documentation (#7148) # Objective `bevy_reflect` can be a moderately complex crate to try and understand. It has many moving parts, a handful of gotchas, and a few subtle contracts that aren't immediately obvious to users and even other contributors. The current README does an okay job demonstrating how the crate can be used. However, the crate's actual documentation should give a better overview of the crate, its inner-workings, and show some of its own examples. ## Solution Added crate-level documentation that attempts to summarize the main parts of `bevy_reflect` into small sections. This PR also updates the documentation for: - `Reflect` - `FromReflect` - The reflection subtraits - Other important types and traits - The reflection macros (including the derive macros) - Crate features ### Open Questions 1. ~~Should I update the docs for the Dynamic types? I was originally going to, but I'm getting a little concerned about the size of this PR 😅~~ Decided to not do this in this PR. It'll be better served from its own PR. 2. Should derive macro documentation be moved to the trait itself? This could improve visibility and allow for better doc links, but could also clutter up the trait's documentation (as well as not being on the actual derive macro's documentation). ### TODO - [ ] ~~Document Dynamic types (?)~~ I think this should be done in a separate PR. - [x] Document crate features - [x] Update docs for `GetTypeRegistration` - [x] Update docs for `TypeRegistration` - [x] Update docs for `derive_from_reflect` - [x] Document `reflect_trait` - [x] Document `impl_reflect_value` - [x] Document `impl_from_reflect_value` --- ## Changelog - Updated documentation across the `bevy_reflect` crate - Removed `#[module]` helper attribute for `Reflect` derives (this is not currently used) ## Migration Guide - Removed `#[module]` helper attribute for `Reflect` derives. If your code is relying on this attribute, please replace it with either `#[reflect]` or `#[reflect_value]` (dependent on use-case). Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2023-02-18 20:42:01 +00:00
/// This corresponds to true Rust arrays like `[T; N]`,
/// but also to any fixed-size linear sequence types.
/// It is expected that implementors of this trait uphold this contract
/// and maintain a fixed size as returned by the [`Array::len`] method.
///
bevy_reflect: Improved documentation (#7148) # Objective `bevy_reflect` can be a moderately complex crate to try and understand. It has many moving parts, a handful of gotchas, and a few subtle contracts that aren't immediately obvious to users and even other contributors. The current README does an okay job demonstrating how the crate can be used. However, the crate's actual documentation should give a better overview of the crate, its inner-workings, and show some of its own examples. ## Solution Added crate-level documentation that attempts to summarize the main parts of `bevy_reflect` into small sections. This PR also updates the documentation for: - `Reflect` - `FromReflect` - The reflection subtraits - Other important types and traits - The reflection macros (including the derive macros) - Crate features ### Open Questions 1. ~~Should I update the docs for the Dynamic types? I was originally going to, but I'm getting a little concerned about the size of this PR 😅~~ Decided to not do this in this PR. It'll be better served from its own PR. 2. Should derive macro documentation be moved to the trait itself? This could improve visibility and allow for better doc links, but could also clutter up the trait's documentation (as well as not being on the actual derive macro's documentation). ### TODO - [ ] ~~Document Dynamic types (?)~~ I think this should be done in a separate PR. - [x] Document crate features - [x] Update docs for `GetTypeRegistration` - [x] Update docs for `TypeRegistration` - [x] Update docs for `derive_from_reflect` - [x] Document `reflect_trait` - [x] Document `impl_reflect_value` - [x] Document `impl_from_reflect_value` --- ## Changelog - Updated documentation across the `bevy_reflect` crate - Removed `#[module]` helper attribute for `Reflect` derives (this is not currently used) ## Migration Guide - Removed `#[module]` helper attribute for `Reflect` derives. If your code is relying on this attribute, please replace it with either `#[reflect]` or `#[reflect_value]` (dependent on use-case). Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2023-02-18 20:42:01 +00:00
/// Due to the [type-erasing] nature of the reflection API as a whole,
/// this trait does not make any guarantees that the implementor's elements
/// are homogenous (i.e. all the same type).
///
bevy_reflect: Improved documentation (#7148) # Objective `bevy_reflect` can be a moderately complex crate to try and understand. It has many moving parts, a handful of gotchas, and a few subtle contracts that aren't immediately obvious to users and even other contributors. The current README does an okay job demonstrating how the crate can be used. However, the crate's actual documentation should give a better overview of the crate, its inner-workings, and show some of its own examples. ## Solution Added crate-level documentation that attempts to summarize the main parts of `bevy_reflect` into small sections. This PR also updates the documentation for: - `Reflect` - `FromReflect` - The reflection subtraits - Other important types and traits - The reflection macros (including the derive macros) - Crate features ### Open Questions 1. ~~Should I update the docs for the Dynamic types? I was originally going to, but I'm getting a little concerned about the size of this PR 😅~~ Decided to not do this in this PR. It'll be better served from its own PR. 2. Should derive macro documentation be moved to the trait itself? This could improve visibility and allow for better doc links, but could also clutter up the trait's documentation (as well as not being on the actual derive macro's documentation). ### TODO - [ ] ~~Document Dynamic types (?)~~ I think this should be done in a separate PR. - [x] Document crate features - [x] Update docs for `GetTypeRegistration` - [x] Update docs for `TypeRegistration` - [x] Update docs for `derive_from_reflect` - [x] Document `reflect_trait` - [x] Document `impl_reflect_value` - [x] Document `impl_from_reflect_value` --- ## Changelog - Updated documentation across the `bevy_reflect` crate - Removed `#[module]` helper attribute for `Reflect` derives (this is not currently used) ## Migration Guide - Removed `#[module]` helper attribute for `Reflect` derives. If your code is relying on this attribute, please replace it with either `#[reflect]` or `#[reflect_value]` (dependent on use-case). Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2023-02-18 20:42:01 +00:00
/// This trait has a blanket implementation over Rust arrays of up to 32 items.
/// This implementation can technically contain more than 32,
/// but the blanket [`GetTypeRegistration`] is only implemented up to the 32
/// item limit due to a [limitation] on [`Deserialize`].
///
/// # Example
///
/// ```
/// use bevy_reflect::{Reflect, Array};
///
/// let foo: &dyn Array = &[123_u32, 456_u32, 789_u32];
/// assert_eq!(foo.len(), 3);
///
/// let field: &dyn Reflect = foo.get(0).unwrap();
/// assert_eq!(field.downcast_ref::<u32>(), Some(&123));
/// ```
///
/// [array-like]: https://doc.rust-lang.org/book/ch03-02-data-types.html#the-array-type
/// [reflection]: crate
/// [`List`]: crate::List
/// [type-erasing]: https://doc.rust-lang.org/book/ch17-02-trait-objects.html
/// [`GetTypeRegistration`]: crate::GetTypeRegistration
/// [limitation]: https://github.com/serde-rs/serde/issues/1937
bevy_reflect: Improved documentation (#7148) # Objective `bevy_reflect` can be a moderately complex crate to try and understand. It has many moving parts, a handful of gotchas, and a few subtle contracts that aren't immediately obvious to users and even other contributors. The current README does an okay job demonstrating how the crate can be used. However, the crate's actual documentation should give a better overview of the crate, its inner-workings, and show some of its own examples. ## Solution Added crate-level documentation that attempts to summarize the main parts of `bevy_reflect` into small sections. This PR also updates the documentation for: - `Reflect` - `FromReflect` - The reflection subtraits - Other important types and traits - The reflection macros (including the derive macros) - Crate features ### Open Questions 1. ~~Should I update the docs for the Dynamic types? I was originally going to, but I'm getting a little concerned about the size of this PR 😅~~ Decided to not do this in this PR. It'll be better served from its own PR. 2. Should derive macro documentation be moved to the trait itself? This could improve visibility and allow for better doc links, but could also clutter up the trait's documentation (as well as not being on the actual derive macro's documentation). ### TODO - [ ] ~~Document Dynamic types (?)~~ I think this should be done in a separate PR. - [x] Document crate features - [x] Update docs for `GetTypeRegistration` - [x] Update docs for `TypeRegistration` - [x] Update docs for `derive_from_reflect` - [x] Document `reflect_trait` - [x] Document `impl_reflect_value` - [x] Document `impl_from_reflect_value` --- ## Changelog - Updated documentation across the `bevy_reflect` crate - Removed `#[module]` helper attribute for `Reflect` derives (this is not currently used) ## Migration Guide - Removed `#[module]` helper attribute for `Reflect` derives. If your code is relying on this attribute, please replace it with either `#[reflect]` or `#[reflect_value]` (dependent on use-case). Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2023-02-18 20:42:01 +00:00
/// [`Deserialize`]: ::serde::Deserialize
pub trait Array: Reflect {
/// Returns a reference to the element at `index`, or `None` if out of bounds.
fn get(&self, index: usize) -> Option<&dyn Reflect>;
bevy_reflect: Decouple `List` and `Array` traits (#7467) # Objective Resolves #7121 ## Solution Decouples `List` and `Array` by removing `Array` as a supertrait of `List`. Additionally, similar methods from `Array` have been added to `List` so that their usages can remain largely unchanged. #### Possible Alternatives ##### `Sequence` My guess for why we originally made `List` a subtrait of `Array` is that they share a lot of common operations. We could potentially move these overlapping methods to a `Sequence` (name taken from #7059) trait and make that a supertrait of both. This would allow functions to contain logic that simply operates on a sequence rather than "list vs array". However, this means that we'd need to add methods for converting to a `dyn Sequence`. It also might be confusing since we wouldn't add a `ReflectRef::Sequence` or anything like that. Is such a trait worth adding (either in this PR or a followup one)? --- ## Changelog - Removed `Array` as supertrait of `List` - Added methods to `List` that were previously provided by `Array` ## Migration Guide The `List` trait is no longer dependent on `Array`. Implementors of `List` can remove the `Array` impl and move its methods into the `List` impl (with only a couple tweaks). ```rust // BEFORE impl Array for Foo { fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */} fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */} fn len(&self) -> usize {/* ... */} fn is_empty(&self) -> bool {/* ... */} fn iter(&self) -> ArrayIter {/* ... */} fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicArray {/* ... */} } impl List for Foo { fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */} fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */} fn push(&mut self, value: Box<dyn Reflect>) {/* ... */} fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicList {/* ... */} } // AFTER impl List for Foo { fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */} fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */} fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */} fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */} fn push(&mut self, value: Box<dyn Reflect>) {/* ... */} fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */} fn len(&self) -> usize {/* ... */} fn is_empty(&self) -> bool {/* ... */} fn iter(&self) -> ListIter {/* ... */} fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicList {/* ... */} } ``` Some other small tweaks that will need to be made include: - Use `ListIter` for `List::iter` instead of `ArrayIter` (the return type from `Array::iter`) - Replace `array_hash` with `list_hash` in `Reflect::reflect_hash` for implementors of `List`
2023-02-13 21:07:53 +00:00
/// Returns a mutable reference to the element at `index`, or `None` if out of bounds.
fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect>;
bevy_reflect: Decouple `List` and `Array` traits (#7467) # Objective Resolves #7121 ## Solution Decouples `List` and `Array` by removing `Array` as a supertrait of `List`. Additionally, similar methods from `Array` have been added to `List` so that their usages can remain largely unchanged. #### Possible Alternatives ##### `Sequence` My guess for why we originally made `List` a subtrait of `Array` is that they share a lot of common operations. We could potentially move these overlapping methods to a `Sequence` (name taken from #7059) trait and make that a supertrait of both. This would allow functions to contain logic that simply operates on a sequence rather than "list vs array". However, this means that we'd need to add methods for converting to a `dyn Sequence`. It also might be confusing since we wouldn't add a `ReflectRef::Sequence` or anything like that. Is such a trait worth adding (either in this PR or a followup one)? --- ## Changelog - Removed `Array` as supertrait of `List` - Added methods to `List` that were previously provided by `Array` ## Migration Guide The `List` trait is no longer dependent on `Array`. Implementors of `List` can remove the `Array` impl and move its methods into the `List` impl (with only a couple tweaks). ```rust // BEFORE impl Array for Foo { fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */} fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */} fn len(&self) -> usize {/* ... */} fn is_empty(&self) -> bool {/* ... */} fn iter(&self) -> ArrayIter {/* ... */} fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicArray {/* ... */} } impl List for Foo { fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */} fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */} fn push(&mut self, value: Box<dyn Reflect>) {/* ... */} fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicList {/* ... */} } // AFTER impl List for Foo { fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */} fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */} fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */} fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */} fn push(&mut self, value: Box<dyn Reflect>) {/* ... */} fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */} fn len(&self) -> usize {/* ... */} fn is_empty(&self) -> bool {/* ... */} fn iter(&self) -> ListIter {/* ... */} fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicList {/* ... */} } ``` Some other small tweaks that will need to be made include: - Use `ListIter` for `List::iter` instead of `ArrayIter` (the return type from `Array::iter`) - Replace `array_hash` with `list_hash` in `Reflect::reflect_hash` for implementors of `List`
2023-02-13 21:07:53 +00:00
/// Returns the number of elements in the array.
fn len(&self) -> usize;
bevy_reflect: Decouple `List` and `Array` traits (#7467) # Objective Resolves #7121 ## Solution Decouples `List` and `Array` by removing `Array` as a supertrait of `List`. Additionally, similar methods from `Array` have been added to `List` so that their usages can remain largely unchanged. #### Possible Alternatives ##### `Sequence` My guess for why we originally made `List` a subtrait of `Array` is that they share a lot of common operations. We could potentially move these overlapping methods to a `Sequence` (name taken from #7059) trait and make that a supertrait of both. This would allow functions to contain logic that simply operates on a sequence rather than "list vs array". However, this means that we'd need to add methods for converting to a `dyn Sequence`. It also might be confusing since we wouldn't add a `ReflectRef::Sequence` or anything like that. Is such a trait worth adding (either in this PR or a followup one)? --- ## Changelog - Removed `Array` as supertrait of `List` - Added methods to `List` that were previously provided by `Array` ## Migration Guide The `List` trait is no longer dependent on `Array`. Implementors of `List` can remove the `Array` impl and move its methods into the `List` impl (with only a couple tweaks). ```rust // BEFORE impl Array for Foo { fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */} fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */} fn len(&self) -> usize {/* ... */} fn is_empty(&self) -> bool {/* ... */} fn iter(&self) -> ArrayIter {/* ... */} fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicArray {/* ... */} } impl List for Foo { fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */} fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */} fn push(&mut self, value: Box<dyn Reflect>) {/* ... */} fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicList {/* ... */} } // AFTER impl List for Foo { fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */} fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */} fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */} fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */} fn push(&mut self, value: Box<dyn Reflect>) {/* ... */} fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */} fn len(&self) -> usize {/* ... */} fn is_empty(&self) -> bool {/* ... */} fn iter(&self) -> ListIter {/* ... */} fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicList {/* ... */} } ``` Some other small tweaks that will need to be made include: - Use `ListIter` for `List::iter` instead of `ArrayIter` (the return type from `Array::iter`) - Replace `array_hash` with `list_hash` in `Reflect::reflect_hash` for implementors of `List`
2023-02-13 21:07:53 +00:00
/// Returns `true` if the collection contains no elements.
fn is_empty(&self) -> bool {
self.len() == 0
}
bevy_reflect: Decouple `List` and `Array` traits (#7467) # Objective Resolves #7121 ## Solution Decouples `List` and `Array` by removing `Array` as a supertrait of `List`. Additionally, similar methods from `Array` have been added to `List` so that their usages can remain largely unchanged. #### Possible Alternatives ##### `Sequence` My guess for why we originally made `List` a subtrait of `Array` is that they share a lot of common operations. We could potentially move these overlapping methods to a `Sequence` (name taken from #7059) trait and make that a supertrait of both. This would allow functions to contain logic that simply operates on a sequence rather than "list vs array". However, this means that we'd need to add methods for converting to a `dyn Sequence`. It also might be confusing since we wouldn't add a `ReflectRef::Sequence` or anything like that. Is such a trait worth adding (either in this PR or a followup one)? --- ## Changelog - Removed `Array` as supertrait of `List` - Added methods to `List` that were previously provided by `Array` ## Migration Guide The `List` trait is no longer dependent on `Array`. Implementors of `List` can remove the `Array` impl and move its methods into the `List` impl (with only a couple tweaks). ```rust // BEFORE impl Array for Foo { fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */} fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */} fn len(&self) -> usize {/* ... */} fn is_empty(&self) -> bool {/* ... */} fn iter(&self) -> ArrayIter {/* ... */} fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicArray {/* ... */} } impl List for Foo { fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */} fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */} fn push(&mut self, value: Box<dyn Reflect>) {/* ... */} fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicList {/* ... */} } // AFTER impl List for Foo { fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */} fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */} fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */} fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */} fn push(&mut self, value: Box<dyn Reflect>) {/* ... */} fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */} fn len(&self) -> usize {/* ... */} fn is_empty(&self) -> bool {/* ... */} fn iter(&self) -> ListIter {/* ... */} fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicList {/* ... */} } ``` Some other small tweaks that will need to be made include: - Use `ListIter` for `List::iter` instead of `ArrayIter` (the return type from `Array::iter`) - Replace `array_hash` with `list_hash` in `Reflect::reflect_hash` for implementors of `List`
2023-02-13 21:07:53 +00:00
/// Returns an iterator over the array.
fn iter(&self) -> ArrayIter;
bevy_reflect: Decouple `List` and `Array` traits (#7467) # Objective Resolves #7121 ## Solution Decouples `List` and `Array` by removing `Array` as a supertrait of `List`. Additionally, similar methods from `Array` have been added to `List` so that their usages can remain largely unchanged. #### Possible Alternatives ##### `Sequence` My guess for why we originally made `List` a subtrait of `Array` is that they share a lot of common operations. We could potentially move these overlapping methods to a `Sequence` (name taken from #7059) trait and make that a supertrait of both. This would allow functions to contain logic that simply operates on a sequence rather than "list vs array". However, this means that we'd need to add methods for converting to a `dyn Sequence`. It also might be confusing since we wouldn't add a `ReflectRef::Sequence` or anything like that. Is such a trait worth adding (either in this PR or a followup one)? --- ## Changelog - Removed `Array` as supertrait of `List` - Added methods to `List` that were previously provided by `Array` ## Migration Guide The `List` trait is no longer dependent on `Array`. Implementors of `List` can remove the `Array` impl and move its methods into the `List` impl (with only a couple tweaks). ```rust // BEFORE impl Array for Foo { fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */} fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */} fn len(&self) -> usize {/* ... */} fn is_empty(&self) -> bool {/* ... */} fn iter(&self) -> ArrayIter {/* ... */} fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicArray {/* ... */} } impl List for Foo { fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */} fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */} fn push(&mut self, value: Box<dyn Reflect>) {/* ... */} fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicList {/* ... */} } // AFTER impl List for Foo { fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */} fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */} fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */} fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */} fn push(&mut self, value: Box<dyn Reflect>) {/* ... */} fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */} fn len(&self) -> usize {/* ... */} fn is_empty(&self) -> bool {/* ... */} fn iter(&self) -> ListIter {/* ... */} fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicList {/* ... */} } ``` Some other small tweaks that will need to be made include: - Use `ListIter` for `List::iter` instead of `ArrayIter` (the return type from `Array::iter`) - Replace `array_hash` with `list_hash` in `Reflect::reflect_hash` for implementors of `List`
2023-02-13 21:07:53 +00:00
bevy_reflect: Get owned fields (#5728) # Objective Sometimes it's useful to be able to retrieve all the fields of a container type so that they may be processed separately. With reflection, however, we typically only have access to references. The only alternative is to "clone" the value using `Reflect::clone_value`. This, however, returns a Dynamic type in most cases. The solution there would be to use `FromReflect` instead, but this also has a problem in that it means we need to add `FromReflect` as an additional bound. ## Solution Add a `drain` method to all container traits. This returns a `Vec<Box<dyn Reflect>>` (except for `Map` which returns `Vec<(Box<dyn Reflect>, Box<dyn Reflect>)>`). This allows us to do things a lot simpler. For example, if we finished processing a struct and just need a particular value: ```rust // === OLD === // /// May or may not return a Dynamic*** value (even if `container` wasn't a `DynamicStruct`) fn get_output(container: Box<dyn Struct>, output_index: usize) -> Box<dyn Reflect> { container.field_at(output_index).unwrap().clone_value() } // === NEW === // /// Returns _exactly_ whatever was in the given struct fn get_output(container: Box<dyn Struct>, output_index: usize) -> Box<dyn Reflect> { container.drain().remove(output_index).unwrap() } ``` ### Discussion * Is `drain` the best method name? It makes sense that it "drains" all the fields and that it consumes the container in the process, but I'm open to alternatives. --- ## Changelog * Added a `drain` method to the following traits: * `Struct` * `TupleStruct` * `Tuple` * `Array` * `List` * `Map` * `Enum`
2022-08-30 21:20:58 +00:00
/// Drain the elements of this array to get a vector of owned values.
fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>>;
bevy_reflect: Decouple `List` and `Array` traits (#7467) # Objective Resolves #7121 ## Solution Decouples `List` and `Array` by removing `Array` as a supertrait of `List`. Additionally, similar methods from `Array` have been added to `List` so that their usages can remain largely unchanged. #### Possible Alternatives ##### `Sequence` My guess for why we originally made `List` a subtrait of `Array` is that they share a lot of common operations. We could potentially move these overlapping methods to a `Sequence` (name taken from #7059) trait and make that a supertrait of both. This would allow functions to contain logic that simply operates on a sequence rather than "list vs array". However, this means that we'd need to add methods for converting to a `dyn Sequence`. It also might be confusing since we wouldn't add a `ReflectRef::Sequence` or anything like that. Is such a trait worth adding (either in this PR or a followup one)? --- ## Changelog - Removed `Array` as supertrait of `List` - Added methods to `List` that were previously provided by `Array` ## Migration Guide The `List` trait is no longer dependent on `Array`. Implementors of `List` can remove the `Array` impl and move its methods into the `List` impl (with only a couple tweaks). ```rust // BEFORE impl Array for Foo { fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */} fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */} fn len(&self) -> usize {/* ... */} fn is_empty(&self) -> bool {/* ... */} fn iter(&self) -> ArrayIter {/* ... */} fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicArray {/* ... */} } impl List for Foo { fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */} fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */} fn push(&mut self, value: Box<dyn Reflect>) {/* ... */} fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicList {/* ... */} } // AFTER impl List for Foo { fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */} fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */} fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */} fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */} fn push(&mut self, value: Box<dyn Reflect>) {/* ... */} fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */} fn len(&self) -> usize {/* ... */} fn is_empty(&self) -> bool {/* ... */} fn iter(&self) -> ListIter {/* ... */} fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */} fn clone_dynamic(&self) -> DynamicList {/* ... */} } ``` Some other small tweaks that will need to be made include: - Use `ListIter` for `List::iter` instead of `ArrayIter` (the return type from `Array::iter`) - Replace `array_hash` with `list_hash` in `Reflect::reflect_hash` for implementors of `List`
2023-02-13 21:07:53 +00:00
/// Clones the list, producing a [`DynamicArray`].
fn clone_dynamic(&self) -> DynamicArray {
DynamicArray {
bevy_reflect: Better proxies (#6971) # Objective > This PR is based on discussion from #6601 The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as both: 1. Dynamic containers which may hold any arbitrary data 2. Proxy types which may represent any other type Currently, the only way we can represent the proxy-ness of a Dynamic is by giving it a name. ```rust // This is just a dynamic container let mut data = DynamicStruct::default(); // This is a "proxy" data.set_name(std::any::type_name::<Foo>()); ``` This type name is the only way we check that the given Dynamic is a proxy of some other type. When we need to "assert the type" of a `dyn Reflect`, we call `Reflect::type_name` on it. However, because we're only using a string to denote the type, we run into a few gotchas and limitations. For example, hashing a Dynamic proxy may work differently than the type it proxies: ```rust #[derive(Reflect, Hash)] #[reflect(Hash)] struct Foo(i32); let concrete = Foo(123); let dynamic = concrete.clone_dynamic(); let concrete_hash = concrete.reflect_hash(); let dynamic_hash = dynamic.reflect_hash(); // The hashes are not equal because `concrete` uses its own `Hash` impl // while `dynamic` uses a reflection-based hashing algorithm assert_ne!(concrete_hash, dynamic_hash); ``` Because the Dynamic proxy only knows about the name of the type, it's unaware of any other information about it. This means it also differs on `Reflect::reflect_partial_eq`, and may include ignored or skipped fields in places the concrete type wouldn't. ## Solution Rather than having Dynamics pass along just the type name of proxied types, we can instead have them pass around the `TypeInfo`. Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than a `String`: ```diff pub struct DynamicTupleStruct { - type_name: String, + represented_type: Option<&'static TypeInfo>, fields: Vec<Box<dyn Reflect>>, } ``` By changing `Reflect::get_type_info` to `Reflect::represented_type_info`, hopefully we make this behavior a little clearer. And to account for `None` values on these dynamic types, `Reflect::represented_type_info` now returns `Option<&'static TypeInfo>`. ```rust let mut data = DynamicTupleStruct::default(); // Not proxying any specific type assert!(dyn_tuple_struct.represented_type_info().is_none()); let type_info = <Foo as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); // Alternatively: // let dyn_tuple_struct = foo.clone_dynamic(); // Now we're proxying `Foo` assert!(dyn_tuple_struct.represented_type_info().is_some()); ``` This means that we can have full access to all the static type information for the proxied type. Future work would include transitioning more static type information (trait impls, attributes, etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic proxies. ### Alternatives & Rationale > **Note** > These alternatives were written when this PR was first made using a `Proxy` trait. This trait has since been removed. <details> <summary>View</summary> #### Alternative: The `Proxy<T>` Approach I had considered adding something like a `Proxy<T>` type where `T` would be the Dynamic and would contain the proxied type information. This was nice in that it allows us to explicitly determine whether something is a proxy or not at a type level. `Proxy<DynamicStruct>` proxies a struct. Makes sense. The reason I didn't go with this approach is because (1) tuples, (2) complexity, and (3) `PartialReflect`. The `DynamicTuple` struct allows us to represent tuples at runtime. It also allows us to do something you normally can't with tuples: add new fields. Because of this, adding a field immediately invalidates the proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32, NewField)`). By going with this PR's approach, we can just remove the type info on `DynamicTuple` when that happens. However, with the `Proxy<T>` approach, it becomes difficult to represent this behavior— we'd have to completely control how we access data for `T` for each `T`. Secondly, it introduces some added complexities (aside from the manual impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we want to represent it as `dyn Reflect`. What `TypeInfo` do we give it? How would we forward reflection methods to the inner type (remember, we don't have specialization)? How do we separate this from Dynamic types? And finally, how do all this in a way that's both logical and intuitive for users? Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is actually more inline with the [Unique Reflect RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy` trait is really one part of the `PartialReflect` trait introduced in that RFC (it's technically not in that RFC but it fits well with it), where the `PartialReflect` serves as a way for proxies to work _like_ concrete types without having full access to everything a concrete `Reflect` type can do. This would help bridge the gap between the current state of the crate and the implementation of that RFC. All that said, this is still a viable solution. If the community believes this is the better path forward, then we can do that instead. These were just my reasons for not initially going with it in this PR. #### Alternative: The Type Registry Approach The `Proxy` trait is great and all, but how does it solve the original problem? Well, it doesn't— yet! The goal would be to start moving information from the derive macro and its attributes to the generated `TypeInfo` since these are known statically and shouldn't change. For example, adding `ignored: bool` to `[Un]NamedField` or a list of impls. However, there is another way of storing this information. This is, of course, one of the uses of the `TypeRegistry`. If we're worried about Dynamic proxies not aligning with their concrete counterparts, we could move more type information to the registry and require its usage. For example, we could replace `Reflect::reflect_hash(&self)` with `Reflect::reflect_hash(&self, registry: &TypeRegistry)`. That's not the _worst_ thing in the world, but it is an ergonomics loss. Additionally, other attributes may have their own requirements, further restricting what's possible without the registry. The `Reflect::apply` method will require the registry as well now. Why? Well because the `map_apply` function used for the `Reflect::apply` impls on `Map` types depends on `Map::insert_boxed`, which (at least for `DynamicMap`) requires `Reflect::reflect_hash`. The same would apply when adding support for reflection-based diffing, which will require `Reflect::reflect_partial_eq`. Again, this is a totally viable alternative. I just chose not to go with it for the reasons above. If we want to go with it, then we can close this PR and we can pursue this alternative instead. #### Downsides Just to highlight a quick potential downside (likely needs more investigation): retrieving the `TypeInfo` requires acquiring a lock on the `GenericTypeInfoCell` used by the `Typed` impls for generic types (non-generic types use a `OnceBox which should be faster). I am not sure how much of a performance hit that is and will need to run some benchmarks to compare against. </details> ### Open Questions 1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be easier for modding? Perhaps, in that case, we need to update `Typed::type_info` and friends as well? 2. Are the alternatives better than the approach this PR takes? Are there other alternatives? --- ## Changelog ### Changed - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` - This method now returns `Option<&'static TypeInfo>` rather than just `&'static TypeInfo` ### Added - Added `Reflect::is_dynamic` method to indicate when a type is dynamic - Added a `set_represented_type` method on all dynamic types ### Removed - Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead) - Removed `Typed` impls for all dynamic types ## Migration Guide - The Dynamic types no longer take a string type name. Instead, they require a static reference to `TypeInfo`: ```rust #[derive(Reflect)] struct MyTupleStruct(f32, f32); let mut dyn_tuple_struct = DynamicTupleStruct::default(); dyn_tuple_struct.insert(1.23_f32); dyn_tuple_struct.insert(3.21_f32); // BEFORE: let type_name = std::any::type_name::<MyTupleStruct>(); dyn_tuple_struct.set_name(type_name); // AFTER: let type_info = <MyTupleStruct as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); ``` - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` and now also returns an `Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`): ```rust // BEFORE: let info: &'static TypeInfo = value.get_type_info(); // AFTER: let info: &'static TypeInfo = value.represented_type_info().unwrap(); ``` - `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use `Reflect::is_dynamic` instead: ```rust // BEFORE: if matches!(value.get_type_info(), TypeInfo::Dynamic) { // ... } // AFTER: if value.is_dynamic() { // ... } ``` --------- Co-authored-by: radiish <cb.setho@gmail.com>
2023-04-26 12:17:46 +00:00
represented_type: self.get_represented_type_info(),
values: self.iter().map(|value| value.clone_value()).collect(),
}
}
}
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::new::<T>()]; let info = TupleStructInfo::new::<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 (aa5178e7736a6f8252e10e543e52722107649d3f) and main (c309acd4322b1c3b2089e247a2d28b938eb7b56d). <details> <summary>See More</summary> The test project included 250 of the following structs (as well as a few other structs): ```rust #[derive(Default)] #[cfg_attr(feature = "reflect", derive(Reflect))] #[cfg_attr(feature = "from_reflect", derive(FromReflect))] pub struct Big001 { inventory: Inventory, foo: usize, bar: String, baz: ItemDescriptor, items: [Item; 20], hello: Option<String>, world: HashMap<i32, String>, okay: (isize, usize, /* wesize */), nope: ((String, String), (f32, f32)), blah: Cow<'static, str>, } ``` > I don't know if the compiler can optimize all these duplicate structs away, but I think it's fine either way. We're comparing times, not finding the absolute worst-case time. I only ran each build 3 times using `cargo build --timings` (thank you @devil-ira), each of which were preceeded by a `cargo clean --package bevy_reflect_compile_test`. Here are the times I got: | Test | Test 1 | Test 2 | Test 3 | Average | | -------------------------------- | ------ | ------ | ------ | ------- | | Main | 1.7s | 3.1s | 1.9s | 2.33s | | Main + `Reflect` | 8.3s | 8.6s | 8.1s | 8.33s | | Main + `Reflect` + `FromReflect` | 11.6s | 11.8s | 13.8s | 12.4s | | PR | 3.5s | 1.8s | 1.9s | 2.4s | | PR + `Reflect` | 9.2s | 8.8s | 9.3s | 9.1s | | PR + `Reflect` + `FromReflect` | 12.9s | 12.3s | 12.5s | 12.56s | </details> --- ## Future Work Even though everything could probably be made `const`, we unfortunately can't. This is because `TypeId::of::<T>()` is not yet `const` (see https://github.com/rust-lang/rust/issues/77125). When it does get stabilized, it would probably be worth coming back and making things `const`. Co-authored-by: MrGVSV <49806985+MrGVSV@users.noreply.github.com>
2022-06-09 21:18:15 +00:00
/// A container for compile-time array info.
#[derive(Clone, Debug)]
pub struct ArrayInfo {
type_name: &'static str,
type_id: TypeId,
item_type_name: &'static str,
item_type_id: TypeId,
capacity: usize,
#[cfg(feature = "documentation")]
docs: Option<&'static str>,
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::new::<T>()]; let info = TupleStructInfo::new::<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 (aa5178e7736a6f8252e10e543e52722107649d3f) and main (c309acd4322b1c3b2089e247a2d28b938eb7b56d). <details> <summary>See More</summary> The test project included 250 of the following structs (as well as a few other structs): ```rust #[derive(Default)] #[cfg_attr(feature = "reflect", derive(Reflect))] #[cfg_attr(feature = "from_reflect", derive(FromReflect))] pub struct Big001 { inventory: Inventory, foo: usize, bar: String, baz: ItemDescriptor, items: [Item; 20], hello: Option<String>, world: HashMap<i32, String>, okay: (isize, usize, /* wesize */), nope: ((String, String), (f32, f32)), blah: Cow<'static, str>, } ``` > I don't know if the compiler can optimize all these duplicate structs away, but I think it's fine either way. We're comparing times, not finding the absolute worst-case time. I only ran each build 3 times using `cargo build --timings` (thank you @devil-ira), each of which were preceeded by a `cargo clean --package bevy_reflect_compile_test`. Here are the times I got: | Test | Test 1 | Test 2 | Test 3 | Average | | -------------------------------- | ------ | ------ | ------ | ------- | | Main | 1.7s | 3.1s | 1.9s | 2.33s | | Main + `Reflect` | 8.3s | 8.6s | 8.1s | 8.33s | | Main + `Reflect` + `FromReflect` | 11.6s | 11.8s | 13.8s | 12.4s | | PR | 3.5s | 1.8s | 1.9s | 2.4s | | PR + `Reflect` | 9.2s | 8.8s | 9.3s | 9.1s | | PR + `Reflect` + `FromReflect` | 12.9s | 12.3s | 12.5s | 12.56s | </details> --- ## Future Work Even though everything could probably be made `const`, we unfortunately can't. This is because `TypeId::of::<T>()` is not yet `const` (see https://github.com/rust-lang/rust/issues/77125). When it does get stabilized, it would probably be worth coming back and making things `const`. Co-authored-by: MrGVSV <49806985+MrGVSV@users.noreply.github.com>
2022-06-09 21:18:15 +00:00
}
impl ArrayInfo {
/// Create a new [`ArrayInfo`].
///
/// # Arguments
///
/// * `capacity`: The maximum capacity of the underlying array.
///
pub fn new<TArray: Array, TItem: Reflect>(capacity: usize) -> Self {
Self {
type_name: std::any::type_name::<TArray>(),
type_id: TypeId::of::<TArray>(),
item_type_name: std::any::type_name::<TItem>(),
item_type_id: TypeId::of::<TItem>(),
capacity,
#[cfg(feature = "documentation")]
docs: None,
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::new::<T>()]; let info = TupleStructInfo::new::<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 (aa5178e7736a6f8252e10e543e52722107649d3f) and main (c309acd4322b1c3b2089e247a2d28b938eb7b56d). <details> <summary>See More</summary> The test project included 250 of the following structs (as well as a few other structs): ```rust #[derive(Default)] #[cfg_attr(feature = "reflect", derive(Reflect))] #[cfg_attr(feature = "from_reflect", derive(FromReflect))] pub struct Big001 { inventory: Inventory, foo: usize, bar: String, baz: ItemDescriptor, items: [Item; 20], hello: Option<String>, world: HashMap<i32, String>, okay: (isize, usize, /* wesize */), nope: ((String, String), (f32, f32)), blah: Cow<'static, str>, } ``` > I don't know if the compiler can optimize all these duplicate structs away, but I think it's fine either way. We're comparing times, not finding the absolute worst-case time. I only ran each build 3 times using `cargo build --timings` (thank you @devil-ira), each of which were preceeded by a `cargo clean --package bevy_reflect_compile_test`. Here are the times I got: | Test | Test 1 | Test 2 | Test 3 | Average | | -------------------------------- | ------ | ------ | ------ | ------- | | Main | 1.7s | 3.1s | 1.9s | 2.33s | | Main + `Reflect` | 8.3s | 8.6s | 8.1s | 8.33s | | Main + `Reflect` + `FromReflect` | 11.6s | 11.8s | 13.8s | 12.4s | | PR | 3.5s | 1.8s | 1.9s | 2.4s | | PR + `Reflect` | 9.2s | 8.8s | 9.3s | 9.1s | | PR + `Reflect` + `FromReflect` | 12.9s | 12.3s | 12.5s | 12.56s | </details> --- ## Future Work Even though everything could probably be made `const`, we unfortunately can't. This is because `TypeId::of::<T>()` is not yet `const` (see https://github.com/rust-lang/rust/issues/77125). When it does get stabilized, it would probably be worth coming back and making things `const`. Co-authored-by: MrGVSV <49806985+MrGVSV@users.noreply.github.com>
2022-06-09 21:18:15 +00:00
}
}
/// Sets the docstring for this array.
#[cfg(feature = "documentation")]
pub fn with_docs(self, docs: Option<&'static str>) -> Self {
Self { docs, ..self }
}
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::new::<T>()]; let info = TupleStructInfo::new::<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 (aa5178e7736a6f8252e10e543e52722107649d3f) and main (c309acd4322b1c3b2089e247a2d28b938eb7b56d). <details> <summary>See More</summary> The test project included 250 of the following structs (as well as a few other structs): ```rust #[derive(Default)] #[cfg_attr(feature = "reflect", derive(Reflect))] #[cfg_attr(feature = "from_reflect", derive(FromReflect))] pub struct Big001 { inventory: Inventory, foo: usize, bar: String, baz: ItemDescriptor, items: [Item; 20], hello: Option<String>, world: HashMap<i32, String>, okay: (isize, usize, /* wesize */), nope: ((String, String), (f32, f32)), blah: Cow<'static, str>, } ``` > I don't know if the compiler can optimize all these duplicate structs away, but I think it's fine either way. We're comparing times, not finding the absolute worst-case time. I only ran each build 3 times using `cargo build --timings` (thank you @devil-ira), each of which were preceeded by a `cargo clean --package bevy_reflect_compile_test`. Here are the times I got: | Test | Test 1 | Test 2 | Test 3 | Average | | -------------------------------- | ------ | ------ | ------ | ------- | | Main | 1.7s | 3.1s | 1.9s | 2.33s | | Main + `Reflect` | 8.3s | 8.6s | 8.1s | 8.33s | | Main + `Reflect` + `FromReflect` | 11.6s | 11.8s | 13.8s | 12.4s | | PR | 3.5s | 1.8s | 1.9s | 2.4s | | PR + `Reflect` | 9.2s | 8.8s | 9.3s | 9.1s | | PR + `Reflect` + `FromReflect` | 12.9s | 12.3s | 12.5s | 12.56s | </details> --- ## Future Work Even though everything could probably be made `const`, we unfortunately can't. This is because `TypeId::of::<T>()` is not yet `const` (see https://github.com/rust-lang/rust/issues/77125). When it does get stabilized, it would probably be worth coming back and making things `const`. Co-authored-by: MrGVSV <49806985+MrGVSV@users.noreply.github.com>
2022-06-09 21:18:15 +00:00
/// The compile-time capacity of the array.
pub fn capacity(&self) -> usize {
self.capacity
}
/// The [type name] of the array.
///
/// [type name]: std::any::type_name
pub fn type_name(&self) -> &'static str {
self.type_name
}
/// The [`TypeId`] of the array.
pub fn type_id(&self) -> TypeId {
self.type_id
}
/// Check if the given type matches the array type.
pub fn is<T: Any>(&self) -> bool {
TypeId::of::<T>() == self.type_id
}
/// The [type name] of the array item.
///
/// [type name]: std::any::type_name
pub fn item_type_name(&self) -> &'static str {
self.item_type_name
}
/// The [`TypeId`] of the array item.
pub fn item_type_id(&self) -> TypeId {
self.item_type_id
}
/// Check if the given type matches the array item type.
pub fn item_is<T: Any>(&self) -> bool {
TypeId::of::<T>() == self.item_type_id
}
/// The docstring of this array, if any.
#[cfg(feature = "documentation")]
pub fn docs(&self) -> Option<&'static str> {
self.docs
}
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::new::<T>()]; let info = TupleStructInfo::new::<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 (aa5178e7736a6f8252e10e543e52722107649d3f) and main (c309acd4322b1c3b2089e247a2d28b938eb7b56d). <details> <summary>See More</summary> The test project included 250 of the following structs (as well as a few other structs): ```rust #[derive(Default)] #[cfg_attr(feature = "reflect", derive(Reflect))] #[cfg_attr(feature = "from_reflect", derive(FromReflect))] pub struct Big001 { inventory: Inventory, foo: usize, bar: String, baz: ItemDescriptor, items: [Item; 20], hello: Option<String>, world: HashMap<i32, String>, okay: (isize, usize, /* wesize */), nope: ((String, String), (f32, f32)), blah: Cow<'static, str>, } ``` > I don't know if the compiler can optimize all these duplicate structs away, but I think it's fine either way. We're comparing times, not finding the absolute worst-case time. I only ran each build 3 times using `cargo build --timings` (thank you @devil-ira), each of which were preceeded by a `cargo clean --package bevy_reflect_compile_test`. Here are the times I got: | Test | Test 1 | Test 2 | Test 3 | Average | | -------------------------------- | ------ | ------ | ------ | ------- | | Main | 1.7s | 3.1s | 1.9s | 2.33s | | Main + `Reflect` | 8.3s | 8.6s | 8.1s | 8.33s | | Main + `Reflect` + `FromReflect` | 11.6s | 11.8s | 13.8s | 12.4s | | PR | 3.5s | 1.8s | 1.9s | 2.4s | | PR + `Reflect` | 9.2s | 8.8s | 9.3s | 9.1s | | PR + `Reflect` + `FromReflect` | 12.9s | 12.3s | 12.5s | 12.56s | </details> --- ## Future Work Even though everything could probably be made `const`, we unfortunately can't. This is because `TypeId::of::<T>()` is not yet `const` (see https://github.com/rust-lang/rust/issues/77125). When it does get stabilized, it would probably be worth coming back and making things `const`. Co-authored-by: MrGVSV <49806985+MrGVSV@users.noreply.github.com>
2022-06-09 21:18:15 +00:00
}
/// A fixed-size list of reflected values.
///
/// This differs from [`DynamicList`] in that the size of the [`DynamicArray`]
/// is constant, whereas a [`DynamicList`] can have items added and removed.
///
/// This isn't to say that a [`DynamicArray`] is immutable— its items
/// can be mutated— just that the _number_ of items cannot change.
///
/// [`DynamicList`]: crate::DynamicList
#[derive(Debug)]
pub struct DynamicArray {
bevy_reflect: Better proxies (#6971) # Objective > This PR is based on discussion from #6601 The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as both: 1. Dynamic containers which may hold any arbitrary data 2. Proxy types which may represent any other type Currently, the only way we can represent the proxy-ness of a Dynamic is by giving it a name. ```rust // This is just a dynamic container let mut data = DynamicStruct::default(); // This is a "proxy" data.set_name(std::any::type_name::<Foo>()); ``` This type name is the only way we check that the given Dynamic is a proxy of some other type. When we need to "assert the type" of a `dyn Reflect`, we call `Reflect::type_name` on it. However, because we're only using a string to denote the type, we run into a few gotchas and limitations. For example, hashing a Dynamic proxy may work differently than the type it proxies: ```rust #[derive(Reflect, Hash)] #[reflect(Hash)] struct Foo(i32); let concrete = Foo(123); let dynamic = concrete.clone_dynamic(); let concrete_hash = concrete.reflect_hash(); let dynamic_hash = dynamic.reflect_hash(); // The hashes are not equal because `concrete` uses its own `Hash` impl // while `dynamic` uses a reflection-based hashing algorithm assert_ne!(concrete_hash, dynamic_hash); ``` Because the Dynamic proxy only knows about the name of the type, it's unaware of any other information about it. This means it also differs on `Reflect::reflect_partial_eq`, and may include ignored or skipped fields in places the concrete type wouldn't. ## Solution Rather than having Dynamics pass along just the type name of proxied types, we can instead have them pass around the `TypeInfo`. Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than a `String`: ```diff pub struct DynamicTupleStruct { - type_name: String, + represented_type: Option<&'static TypeInfo>, fields: Vec<Box<dyn Reflect>>, } ``` By changing `Reflect::get_type_info` to `Reflect::represented_type_info`, hopefully we make this behavior a little clearer. And to account for `None` values on these dynamic types, `Reflect::represented_type_info` now returns `Option<&'static TypeInfo>`. ```rust let mut data = DynamicTupleStruct::default(); // Not proxying any specific type assert!(dyn_tuple_struct.represented_type_info().is_none()); let type_info = <Foo as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); // Alternatively: // let dyn_tuple_struct = foo.clone_dynamic(); // Now we're proxying `Foo` assert!(dyn_tuple_struct.represented_type_info().is_some()); ``` This means that we can have full access to all the static type information for the proxied type. Future work would include transitioning more static type information (trait impls, attributes, etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic proxies. ### Alternatives & Rationale > **Note** > These alternatives were written when this PR was first made using a `Proxy` trait. This trait has since been removed. <details> <summary>View</summary> #### Alternative: The `Proxy<T>` Approach I had considered adding something like a `Proxy<T>` type where `T` would be the Dynamic and would contain the proxied type information. This was nice in that it allows us to explicitly determine whether something is a proxy or not at a type level. `Proxy<DynamicStruct>` proxies a struct. Makes sense. The reason I didn't go with this approach is because (1) tuples, (2) complexity, and (3) `PartialReflect`. The `DynamicTuple` struct allows us to represent tuples at runtime. It also allows us to do something you normally can't with tuples: add new fields. Because of this, adding a field immediately invalidates the proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32, NewField)`). By going with this PR's approach, we can just remove the type info on `DynamicTuple` when that happens. However, with the `Proxy<T>` approach, it becomes difficult to represent this behavior— we'd have to completely control how we access data for `T` for each `T`. Secondly, it introduces some added complexities (aside from the manual impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we want to represent it as `dyn Reflect`. What `TypeInfo` do we give it? How would we forward reflection methods to the inner type (remember, we don't have specialization)? How do we separate this from Dynamic types? And finally, how do all this in a way that's both logical and intuitive for users? Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is actually more inline with the [Unique Reflect RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy` trait is really one part of the `PartialReflect` trait introduced in that RFC (it's technically not in that RFC but it fits well with it), where the `PartialReflect` serves as a way for proxies to work _like_ concrete types without having full access to everything a concrete `Reflect` type can do. This would help bridge the gap between the current state of the crate and the implementation of that RFC. All that said, this is still a viable solution. If the community believes this is the better path forward, then we can do that instead. These were just my reasons for not initially going with it in this PR. #### Alternative: The Type Registry Approach The `Proxy` trait is great and all, but how does it solve the original problem? Well, it doesn't— yet! The goal would be to start moving information from the derive macro and its attributes to the generated `TypeInfo` since these are known statically and shouldn't change. For example, adding `ignored: bool` to `[Un]NamedField` or a list of impls. However, there is another way of storing this information. This is, of course, one of the uses of the `TypeRegistry`. If we're worried about Dynamic proxies not aligning with their concrete counterparts, we could move more type information to the registry and require its usage. For example, we could replace `Reflect::reflect_hash(&self)` with `Reflect::reflect_hash(&self, registry: &TypeRegistry)`. That's not the _worst_ thing in the world, but it is an ergonomics loss. Additionally, other attributes may have their own requirements, further restricting what's possible without the registry. The `Reflect::apply` method will require the registry as well now. Why? Well because the `map_apply` function used for the `Reflect::apply` impls on `Map` types depends on `Map::insert_boxed`, which (at least for `DynamicMap`) requires `Reflect::reflect_hash`. The same would apply when adding support for reflection-based diffing, which will require `Reflect::reflect_partial_eq`. Again, this is a totally viable alternative. I just chose not to go with it for the reasons above. If we want to go with it, then we can close this PR and we can pursue this alternative instead. #### Downsides Just to highlight a quick potential downside (likely needs more investigation): retrieving the `TypeInfo` requires acquiring a lock on the `GenericTypeInfoCell` used by the `Typed` impls for generic types (non-generic types use a `OnceBox which should be faster). I am not sure how much of a performance hit that is and will need to run some benchmarks to compare against. </details> ### Open Questions 1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be easier for modding? Perhaps, in that case, we need to update `Typed::type_info` and friends as well? 2. Are the alternatives better than the approach this PR takes? Are there other alternatives? --- ## Changelog ### Changed - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` - This method now returns `Option<&'static TypeInfo>` rather than just `&'static TypeInfo` ### Added - Added `Reflect::is_dynamic` method to indicate when a type is dynamic - Added a `set_represented_type` method on all dynamic types ### Removed - Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead) - Removed `Typed` impls for all dynamic types ## Migration Guide - The Dynamic types no longer take a string type name. Instead, they require a static reference to `TypeInfo`: ```rust #[derive(Reflect)] struct MyTupleStruct(f32, f32); let mut dyn_tuple_struct = DynamicTupleStruct::default(); dyn_tuple_struct.insert(1.23_f32); dyn_tuple_struct.insert(3.21_f32); // BEFORE: let type_name = std::any::type_name::<MyTupleStruct>(); dyn_tuple_struct.set_name(type_name); // AFTER: let type_info = <MyTupleStruct as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); ``` - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` and now also returns an `Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`): ```rust // BEFORE: let info: &'static TypeInfo = value.get_type_info(); // AFTER: let info: &'static TypeInfo = value.represented_type_info().unwrap(); ``` - `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use `Reflect::is_dynamic` instead: ```rust // BEFORE: if matches!(value.get_type_info(), TypeInfo::Dynamic) { // ... } // AFTER: if value.is_dynamic() { // ... } ``` --------- Co-authored-by: radiish <cb.setho@gmail.com>
2023-04-26 12:17:46 +00:00
pub(crate) represented_type: Option<&'static TypeInfo>,
pub(crate) values: Box<[Box<dyn Reflect>]>,
}
impl DynamicArray {
#[inline]
pub fn new(values: Box<[Box<dyn Reflect>]>) -> Self {
Self {
bevy_reflect: Better proxies (#6971) # Objective > This PR is based on discussion from #6601 The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as both: 1. Dynamic containers which may hold any arbitrary data 2. Proxy types which may represent any other type Currently, the only way we can represent the proxy-ness of a Dynamic is by giving it a name. ```rust // This is just a dynamic container let mut data = DynamicStruct::default(); // This is a "proxy" data.set_name(std::any::type_name::<Foo>()); ``` This type name is the only way we check that the given Dynamic is a proxy of some other type. When we need to "assert the type" of a `dyn Reflect`, we call `Reflect::type_name` on it. However, because we're only using a string to denote the type, we run into a few gotchas and limitations. For example, hashing a Dynamic proxy may work differently than the type it proxies: ```rust #[derive(Reflect, Hash)] #[reflect(Hash)] struct Foo(i32); let concrete = Foo(123); let dynamic = concrete.clone_dynamic(); let concrete_hash = concrete.reflect_hash(); let dynamic_hash = dynamic.reflect_hash(); // The hashes are not equal because `concrete` uses its own `Hash` impl // while `dynamic` uses a reflection-based hashing algorithm assert_ne!(concrete_hash, dynamic_hash); ``` Because the Dynamic proxy only knows about the name of the type, it's unaware of any other information about it. This means it also differs on `Reflect::reflect_partial_eq`, and may include ignored or skipped fields in places the concrete type wouldn't. ## Solution Rather than having Dynamics pass along just the type name of proxied types, we can instead have them pass around the `TypeInfo`. Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than a `String`: ```diff pub struct DynamicTupleStruct { - type_name: String, + represented_type: Option<&'static TypeInfo>, fields: Vec<Box<dyn Reflect>>, } ``` By changing `Reflect::get_type_info` to `Reflect::represented_type_info`, hopefully we make this behavior a little clearer. And to account for `None` values on these dynamic types, `Reflect::represented_type_info` now returns `Option<&'static TypeInfo>`. ```rust let mut data = DynamicTupleStruct::default(); // Not proxying any specific type assert!(dyn_tuple_struct.represented_type_info().is_none()); let type_info = <Foo as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); // Alternatively: // let dyn_tuple_struct = foo.clone_dynamic(); // Now we're proxying `Foo` assert!(dyn_tuple_struct.represented_type_info().is_some()); ``` This means that we can have full access to all the static type information for the proxied type. Future work would include transitioning more static type information (trait impls, attributes, etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic proxies. ### Alternatives & Rationale > **Note** > These alternatives were written when this PR was first made using a `Proxy` trait. This trait has since been removed. <details> <summary>View</summary> #### Alternative: The `Proxy<T>` Approach I had considered adding something like a `Proxy<T>` type where `T` would be the Dynamic and would contain the proxied type information. This was nice in that it allows us to explicitly determine whether something is a proxy or not at a type level. `Proxy<DynamicStruct>` proxies a struct. Makes sense. The reason I didn't go with this approach is because (1) tuples, (2) complexity, and (3) `PartialReflect`. The `DynamicTuple` struct allows us to represent tuples at runtime. It also allows us to do something you normally can't with tuples: add new fields. Because of this, adding a field immediately invalidates the proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32, NewField)`). By going with this PR's approach, we can just remove the type info on `DynamicTuple` when that happens. However, with the `Proxy<T>` approach, it becomes difficult to represent this behavior— we'd have to completely control how we access data for `T` for each `T`. Secondly, it introduces some added complexities (aside from the manual impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we want to represent it as `dyn Reflect`. What `TypeInfo` do we give it? How would we forward reflection methods to the inner type (remember, we don't have specialization)? How do we separate this from Dynamic types? And finally, how do all this in a way that's both logical and intuitive for users? Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is actually more inline with the [Unique Reflect RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy` trait is really one part of the `PartialReflect` trait introduced in that RFC (it's technically not in that RFC but it fits well with it), where the `PartialReflect` serves as a way for proxies to work _like_ concrete types without having full access to everything a concrete `Reflect` type can do. This would help bridge the gap between the current state of the crate and the implementation of that RFC. All that said, this is still a viable solution. If the community believes this is the better path forward, then we can do that instead. These were just my reasons for not initially going with it in this PR. #### Alternative: The Type Registry Approach The `Proxy` trait is great and all, but how does it solve the original problem? Well, it doesn't— yet! The goal would be to start moving information from the derive macro and its attributes to the generated `TypeInfo` since these are known statically and shouldn't change. For example, adding `ignored: bool` to `[Un]NamedField` or a list of impls. However, there is another way of storing this information. This is, of course, one of the uses of the `TypeRegistry`. If we're worried about Dynamic proxies not aligning with their concrete counterparts, we could move more type information to the registry and require its usage. For example, we could replace `Reflect::reflect_hash(&self)` with `Reflect::reflect_hash(&self, registry: &TypeRegistry)`. That's not the _worst_ thing in the world, but it is an ergonomics loss. Additionally, other attributes may have their own requirements, further restricting what's possible without the registry. The `Reflect::apply` method will require the registry as well now. Why? Well because the `map_apply` function used for the `Reflect::apply` impls on `Map` types depends on `Map::insert_boxed`, which (at least for `DynamicMap`) requires `Reflect::reflect_hash`. The same would apply when adding support for reflection-based diffing, which will require `Reflect::reflect_partial_eq`. Again, this is a totally viable alternative. I just chose not to go with it for the reasons above. If we want to go with it, then we can close this PR and we can pursue this alternative instead. #### Downsides Just to highlight a quick potential downside (likely needs more investigation): retrieving the `TypeInfo` requires acquiring a lock on the `GenericTypeInfoCell` used by the `Typed` impls for generic types (non-generic types use a `OnceBox which should be faster). I am not sure how much of a performance hit that is and will need to run some benchmarks to compare against. </details> ### Open Questions 1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be easier for modding? Perhaps, in that case, we need to update `Typed::type_info` and friends as well? 2. Are the alternatives better than the approach this PR takes? Are there other alternatives? --- ## Changelog ### Changed - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` - This method now returns `Option<&'static TypeInfo>` rather than just `&'static TypeInfo` ### Added - Added `Reflect::is_dynamic` method to indicate when a type is dynamic - Added a `set_represented_type` method on all dynamic types ### Removed - Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead) - Removed `Typed` impls for all dynamic types ## Migration Guide - The Dynamic types no longer take a string type name. Instead, they require a static reference to `TypeInfo`: ```rust #[derive(Reflect)] struct MyTupleStruct(f32, f32); let mut dyn_tuple_struct = DynamicTupleStruct::default(); dyn_tuple_struct.insert(1.23_f32); dyn_tuple_struct.insert(3.21_f32); // BEFORE: let type_name = std::any::type_name::<MyTupleStruct>(); dyn_tuple_struct.set_name(type_name); // AFTER: let type_info = <MyTupleStruct as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); ``` - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` and now also returns an `Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`): ```rust // BEFORE: let info: &'static TypeInfo = value.get_type_info(); // AFTER: let info: &'static TypeInfo = value.represented_type_info().unwrap(); ``` - `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use `Reflect::is_dynamic` instead: ```rust // BEFORE: if matches!(value.get_type_info(), TypeInfo::Dynamic) { // ... } // AFTER: if value.is_dynamic() { // ... } ``` --------- Co-authored-by: radiish <cb.setho@gmail.com>
2023-04-26 12:17:46 +00:00
represented_type: None,
values,
}
}
pub fn from_vec<T: Reflect>(values: Vec<T>) -> Self {
Self {
bevy_reflect: Better proxies (#6971) # Objective > This PR is based on discussion from #6601 The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as both: 1. Dynamic containers which may hold any arbitrary data 2. Proxy types which may represent any other type Currently, the only way we can represent the proxy-ness of a Dynamic is by giving it a name. ```rust // This is just a dynamic container let mut data = DynamicStruct::default(); // This is a "proxy" data.set_name(std::any::type_name::<Foo>()); ``` This type name is the only way we check that the given Dynamic is a proxy of some other type. When we need to "assert the type" of a `dyn Reflect`, we call `Reflect::type_name` on it. However, because we're only using a string to denote the type, we run into a few gotchas and limitations. For example, hashing a Dynamic proxy may work differently than the type it proxies: ```rust #[derive(Reflect, Hash)] #[reflect(Hash)] struct Foo(i32); let concrete = Foo(123); let dynamic = concrete.clone_dynamic(); let concrete_hash = concrete.reflect_hash(); let dynamic_hash = dynamic.reflect_hash(); // The hashes are not equal because `concrete` uses its own `Hash` impl // while `dynamic` uses a reflection-based hashing algorithm assert_ne!(concrete_hash, dynamic_hash); ``` Because the Dynamic proxy only knows about the name of the type, it's unaware of any other information about it. This means it also differs on `Reflect::reflect_partial_eq`, and may include ignored or skipped fields in places the concrete type wouldn't. ## Solution Rather than having Dynamics pass along just the type name of proxied types, we can instead have them pass around the `TypeInfo`. Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than a `String`: ```diff pub struct DynamicTupleStruct { - type_name: String, + represented_type: Option<&'static TypeInfo>, fields: Vec<Box<dyn Reflect>>, } ``` By changing `Reflect::get_type_info` to `Reflect::represented_type_info`, hopefully we make this behavior a little clearer. And to account for `None` values on these dynamic types, `Reflect::represented_type_info` now returns `Option<&'static TypeInfo>`. ```rust let mut data = DynamicTupleStruct::default(); // Not proxying any specific type assert!(dyn_tuple_struct.represented_type_info().is_none()); let type_info = <Foo as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); // Alternatively: // let dyn_tuple_struct = foo.clone_dynamic(); // Now we're proxying `Foo` assert!(dyn_tuple_struct.represented_type_info().is_some()); ``` This means that we can have full access to all the static type information for the proxied type. Future work would include transitioning more static type information (trait impls, attributes, etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic proxies. ### Alternatives & Rationale > **Note** > These alternatives were written when this PR was first made using a `Proxy` trait. This trait has since been removed. <details> <summary>View</summary> #### Alternative: The `Proxy<T>` Approach I had considered adding something like a `Proxy<T>` type where `T` would be the Dynamic and would contain the proxied type information. This was nice in that it allows us to explicitly determine whether something is a proxy or not at a type level. `Proxy<DynamicStruct>` proxies a struct. Makes sense. The reason I didn't go with this approach is because (1) tuples, (2) complexity, and (3) `PartialReflect`. The `DynamicTuple` struct allows us to represent tuples at runtime. It also allows us to do something you normally can't with tuples: add new fields. Because of this, adding a field immediately invalidates the proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32, NewField)`). By going with this PR's approach, we can just remove the type info on `DynamicTuple` when that happens. However, with the `Proxy<T>` approach, it becomes difficult to represent this behavior— we'd have to completely control how we access data for `T` for each `T`. Secondly, it introduces some added complexities (aside from the manual impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we want to represent it as `dyn Reflect`. What `TypeInfo` do we give it? How would we forward reflection methods to the inner type (remember, we don't have specialization)? How do we separate this from Dynamic types? And finally, how do all this in a way that's both logical and intuitive for users? Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is actually more inline with the [Unique Reflect RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy` trait is really one part of the `PartialReflect` trait introduced in that RFC (it's technically not in that RFC but it fits well with it), where the `PartialReflect` serves as a way for proxies to work _like_ concrete types without having full access to everything a concrete `Reflect` type can do. This would help bridge the gap between the current state of the crate and the implementation of that RFC. All that said, this is still a viable solution. If the community believes this is the better path forward, then we can do that instead. These were just my reasons for not initially going with it in this PR. #### Alternative: The Type Registry Approach The `Proxy` trait is great and all, but how does it solve the original problem? Well, it doesn't— yet! The goal would be to start moving information from the derive macro and its attributes to the generated `TypeInfo` since these are known statically and shouldn't change. For example, adding `ignored: bool` to `[Un]NamedField` or a list of impls. However, there is another way of storing this information. This is, of course, one of the uses of the `TypeRegistry`. If we're worried about Dynamic proxies not aligning with their concrete counterparts, we could move more type information to the registry and require its usage. For example, we could replace `Reflect::reflect_hash(&self)` with `Reflect::reflect_hash(&self, registry: &TypeRegistry)`. That's not the _worst_ thing in the world, but it is an ergonomics loss. Additionally, other attributes may have their own requirements, further restricting what's possible without the registry. The `Reflect::apply` method will require the registry as well now. Why? Well because the `map_apply` function used for the `Reflect::apply` impls on `Map` types depends on `Map::insert_boxed`, which (at least for `DynamicMap`) requires `Reflect::reflect_hash`. The same would apply when adding support for reflection-based diffing, which will require `Reflect::reflect_partial_eq`. Again, this is a totally viable alternative. I just chose not to go with it for the reasons above. If we want to go with it, then we can close this PR and we can pursue this alternative instead. #### Downsides Just to highlight a quick potential downside (likely needs more investigation): retrieving the `TypeInfo` requires acquiring a lock on the `GenericTypeInfoCell` used by the `Typed` impls for generic types (non-generic types use a `OnceBox which should be faster). I am not sure how much of a performance hit that is and will need to run some benchmarks to compare against. </details> ### Open Questions 1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be easier for modding? Perhaps, in that case, we need to update `Typed::type_info` and friends as well? 2. Are the alternatives better than the approach this PR takes? Are there other alternatives? --- ## Changelog ### Changed - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` - This method now returns `Option<&'static TypeInfo>` rather than just `&'static TypeInfo` ### Added - Added `Reflect::is_dynamic` method to indicate when a type is dynamic - Added a `set_represented_type` method on all dynamic types ### Removed - Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead) - Removed `Typed` impls for all dynamic types ## Migration Guide - The Dynamic types no longer take a string type name. Instead, they require a static reference to `TypeInfo`: ```rust #[derive(Reflect)] struct MyTupleStruct(f32, f32); let mut dyn_tuple_struct = DynamicTupleStruct::default(); dyn_tuple_struct.insert(1.23_f32); dyn_tuple_struct.insert(3.21_f32); // BEFORE: let type_name = std::any::type_name::<MyTupleStruct>(); dyn_tuple_struct.set_name(type_name); // AFTER: let type_info = <MyTupleStruct as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); ``` - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` and now also returns an `Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`): ```rust // BEFORE: let info: &'static TypeInfo = value.get_type_info(); // AFTER: let info: &'static TypeInfo = value.represented_type_info().unwrap(); ``` - `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use `Reflect::is_dynamic` instead: ```rust // BEFORE: if matches!(value.get_type_info(), TypeInfo::Dynamic) { // ... } // AFTER: if value.is_dynamic() { // ... } ``` --------- Co-authored-by: radiish <cb.setho@gmail.com>
2023-04-26 12:17:46 +00:00
represented_type: None,
values: values
.into_iter()
.map(|field| Box::new(field) as Box<dyn Reflect>)
.collect::<Vec<_>>()
.into_boxed_slice(),
}
}
bevy_reflect: Better proxies (#6971) # Objective > This PR is based on discussion from #6601 The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as both: 1. Dynamic containers which may hold any arbitrary data 2. Proxy types which may represent any other type Currently, the only way we can represent the proxy-ness of a Dynamic is by giving it a name. ```rust // This is just a dynamic container let mut data = DynamicStruct::default(); // This is a "proxy" data.set_name(std::any::type_name::<Foo>()); ``` This type name is the only way we check that the given Dynamic is a proxy of some other type. When we need to "assert the type" of a `dyn Reflect`, we call `Reflect::type_name` on it. However, because we're only using a string to denote the type, we run into a few gotchas and limitations. For example, hashing a Dynamic proxy may work differently than the type it proxies: ```rust #[derive(Reflect, Hash)] #[reflect(Hash)] struct Foo(i32); let concrete = Foo(123); let dynamic = concrete.clone_dynamic(); let concrete_hash = concrete.reflect_hash(); let dynamic_hash = dynamic.reflect_hash(); // The hashes are not equal because `concrete` uses its own `Hash` impl // while `dynamic` uses a reflection-based hashing algorithm assert_ne!(concrete_hash, dynamic_hash); ``` Because the Dynamic proxy only knows about the name of the type, it's unaware of any other information about it. This means it also differs on `Reflect::reflect_partial_eq`, and may include ignored or skipped fields in places the concrete type wouldn't. ## Solution Rather than having Dynamics pass along just the type name of proxied types, we can instead have them pass around the `TypeInfo`. Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than a `String`: ```diff pub struct DynamicTupleStruct { - type_name: String, + represented_type: Option<&'static TypeInfo>, fields: Vec<Box<dyn Reflect>>, } ``` By changing `Reflect::get_type_info` to `Reflect::represented_type_info`, hopefully we make this behavior a little clearer. And to account for `None` values on these dynamic types, `Reflect::represented_type_info` now returns `Option<&'static TypeInfo>`. ```rust let mut data = DynamicTupleStruct::default(); // Not proxying any specific type assert!(dyn_tuple_struct.represented_type_info().is_none()); let type_info = <Foo as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); // Alternatively: // let dyn_tuple_struct = foo.clone_dynamic(); // Now we're proxying `Foo` assert!(dyn_tuple_struct.represented_type_info().is_some()); ``` This means that we can have full access to all the static type information for the proxied type. Future work would include transitioning more static type information (trait impls, attributes, etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic proxies. ### Alternatives & Rationale > **Note** > These alternatives were written when this PR was first made using a `Proxy` trait. This trait has since been removed. <details> <summary>View</summary> #### Alternative: The `Proxy<T>` Approach I had considered adding something like a `Proxy<T>` type where `T` would be the Dynamic and would contain the proxied type information. This was nice in that it allows us to explicitly determine whether something is a proxy or not at a type level. `Proxy<DynamicStruct>` proxies a struct. Makes sense. The reason I didn't go with this approach is because (1) tuples, (2) complexity, and (3) `PartialReflect`. The `DynamicTuple` struct allows us to represent tuples at runtime. It also allows us to do something you normally can't with tuples: add new fields. Because of this, adding a field immediately invalidates the proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32, NewField)`). By going with this PR's approach, we can just remove the type info on `DynamicTuple` when that happens. However, with the `Proxy<T>` approach, it becomes difficult to represent this behavior— we'd have to completely control how we access data for `T` for each `T`. Secondly, it introduces some added complexities (aside from the manual impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we want to represent it as `dyn Reflect`. What `TypeInfo` do we give it? How would we forward reflection methods to the inner type (remember, we don't have specialization)? How do we separate this from Dynamic types? And finally, how do all this in a way that's both logical and intuitive for users? Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is actually more inline with the [Unique Reflect RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy` trait is really one part of the `PartialReflect` trait introduced in that RFC (it's technically not in that RFC but it fits well with it), where the `PartialReflect` serves as a way for proxies to work _like_ concrete types without having full access to everything a concrete `Reflect` type can do. This would help bridge the gap between the current state of the crate and the implementation of that RFC. All that said, this is still a viable solution. If the community believes this is the better path forward, then we can do that instead. These were just my reasons for not initially going with it in this PR. #### Alternative: The Type Registry Approach The `Proxy` trait is great and all, but how does it solve the original problem? Well, it doesn't— yet! The goal would be to start moving information from the derive macro and its attributes to the generated `TypeInfo` since these are known statically and shouldn't change. For example, adding `ignored: bool` to `[Un]NamedField` or a list of impls. However, there is another way of storing this information. This is, of course, one of the uses of the `TypeRegistry`. If we're worried about Dynamic proxies not aligning with their concrete counterparts, we could move more type information to the registry and require its usage. For example, we could replace `Reflect::reflect_hash(&self)` with `Reflect::reflect_hash(&self, registry: &TypeRegistry)`. That's not the _worst_ thing in the world, but it is an ergonomics loss. Additionally, other attributes may have their own requirements, further restricting what's possible without the registry. The `Reflect::apply` method will require the registry as well now. Why? Well because the `map_apply` function used for the `Reflect::apply` impls on `Map` types depends on `Map::insert_boxed`, which (at least for `DynamicMap`) requires `Reflect::reflect_hash`. The same would apply when adding support for reflection-based diffing, which will require `Reflect::reflect_partial_eq`. Again, this is a totally viable alternative. I just chose not to go with it for the reasons above. If we want to go with it, then we can close this PR and we can pursue this alternative instead. #### Downsides Just to highlight a quick potential downside (likely needs more investigation): retrieving the `TypeInfo` requires acquiring a lock on the `GenericTypeInfoCell` used by the `Typed` impls for generic types (non-generic types use a `OnceBox which should be faster). I am not sure how much of a performance hit that is and will need to run some benchmarks to compare against. </details> ### Open Questions 1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be easier for modding? Perhaps, in that case, we need to update `Typed::type_info` and friends as well? 2. Are the alternatives better than the approach this PR takes? Are there other alternatives? --- ## Changelog ### Changed - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` - This method now returns `Option<&'static TypeInfo>` rather than just `&'static TypeInfo` ### Added - Added `Reflect::is_dynamic` method to indicate when a type is dynamic - Added a `set_represented_type` method on all dynamic types ### Removed - Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead) - Removed `Typed` impls for all dynamic types ## Migration Guide - The Dynamic types no longer take a string type name. Instead, they require a static reference to `TypeInfo`: ```rust #[derive(Reflect)] struct MyTupleStruct(f32, f32); let mut dyn_tuple_struct = DynamicTupleStruct::default(); dyn_tuple_struct.insert(1.23_f32); dyn_tuple_struct.insert(3.21_f32); // BEFORE: let type_name = std::any::type_name::<MyTupleStruct>(); dyn_tuple_struct.set_name(type_name); // AFTER: let type_info = <MyTupleStruct as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); ``` - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` and now also returns an `Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`): ```rust // BEFORE: let info: &'static TypeInfo = value.get_type_info(); // AFTER: let info: &'static TypeInfo = value.represented_type_info().unwrap(); ``` - `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use `Reflect::is_dynamic` instead: ```rust // BEFORE: if matches!(value.get_type_info(), TypeInfo::Dynamic) { // ... } // AFTER: if value.is_dynamic() { // ... } ``` --------- Co-authored-by: radiish <cb.setho@gmail.com>
2023-04-26 12:17:46 +00:00
/// Sets the [type] to be represented by this `DynamicArray`.
///
/// # Panics
///
/// Panics if the given [type] is not a [`TypeInfo::Array`].
///
/// [type]: TypeInfo
pub fn set_represented_type(&mut self, represented_type: Option<&'static TypeInfo>) {
if let Some(represented_type) = represented_type {
assert!(
matches!(represented_type, TypeInfo::Array(_)),
"expected TypeInfo::Array but received: {:?}",
represented_type
);
}
bevy_reflect: Better proxies (#6971) # Objective > This PR is based on discussion from #6601 The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as both: 1. Dynamic containers which may hold any arbitrary data 2. Proxy types which may represent any other type Currently, the only way we can represent the proxy-ness of a Dynamic is by giving it a name. ```rust // This is just a dynamic container let mut data = DynamicStruct::default(); // This is a "proxy" data.set_name(std::any::type_name::<Foo>()); ``` This type name is the only way we check that the given Dynamic is a proxy of some other type. When we need to "assert the type" of a `dyn Reflect`, we call `Reflect::type_name` on it. However, because we're only using a string to denote the type, we run into a few gotchas and limitations. For example, hashing a Dynamic proxy may work differently than the type it proxies: ```rust #[derive(Reflect, Hash)] #[reflect(Hash)] struct Foo(i32); let concrete = Foo(123); let dynamic = concrete.clone_dynamic(); let concrete_hash = concrete.reflect_hash(); let dynamic_hash = dynamic.reflect_hash(); // The hashes are not equal because `concrete` uses its own `Hash` impl // while `dynamic` uses a reflection-based hashing algorithm assert_ne!(concrete_hash, dynamic_hash); ``` Because the Dynamic proxy only knows about the name of the type, it's unaware of any other information about it. This means it also differs on `Reflect::reflect_partial_eq`, and may include ignored or skipped fields in places the concrete type wouldn't. ## Solution Rather than having Dynamics pass along just the type name of proxied types, we can instead have them pass around the `TypeInfo`. Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than a `String`: ```diff pub struct DynamicTupleStruct { - type_name: String, + represented_type: Option<&'static TypeInfo>, fields: Vec<Box<dyn Reflect>>, } ``` By changing `Reflect::get_type_info` to `Reflect::represented_type_info`, hopefully we make this behavior a little clearer. And to account for `None` values on these dynamic types, `Reflect::represented_type_info` now returns `Option<&'static TypeInfo>`. ```rust let mut data = DynamicTupleStruct::default(); // Not proxying any specific type assert!(dyn_tuple_struct.represented_type_info().is_none()); let type_info = <Foo as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); // Alternatively: // let dyn_tuple_struct = foo.clone_dynamic(); // Now we're proxying `Foo` assert!(dyn_tuple_struct.represented_type_info().is_some()); ``` This means that we can have full access to all the static type information for the proxied type. Future work would include transitioning more static type information (trait impls, attributes, etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic proxies. ### Alternatives & Rationale > **Note** > These alternatives were written when this PR was first made using a `Proxy` trait. This trait has since been removed. <details> <summary>View</summary> #### Alternative: The `Proxy<T>` Approach I had considered adding something like a `Proxy<T>` type where `T` would be the Dynamic and would contain the proxied type information. This was nice in that it allows us to explicitly determine whether something is a proxy or not at a type level. `Proxy<DynamicStruct>` proxies a struct. Makes sense. The reason I didn't go with this approach is because (1) tuples, (2) complexity, and (3) `PartialReflect`. The `DynamicTuple` struct allows us to represent tuples at runtime. It also allows us to do something you normally can't with tuples: add new fields. Because of this, adding a field immediately invalidates the proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32, NewField)`). By going with this PR's approach, we can just remove the type info on `DynamicTuple` when that happens. However, with the `Proxy<T>` approach, it becomes difficult to represent this behavior— we'd have to completely control how we access data for `T` for each `T`. Secondly, it introduces some added complexities (aside from the manual impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we want to represent it as `dyn Reflect`. What `TypeInfo` do we give it? How would we forward reflection methods to the inner type (remember, we don't have specialization)? How do we separate this from Dynamic types? And finally, how do all this in a way that's both logical and intuitive for users? Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is actually more inline with the [Unique Reflect RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy` trait is really one part of the `PartialReflect` trait introduced in that RFC (it's technically not in that RFC but it fits well with it), where the `PartialReflect` serves as a way for proxies to work _like_ concrete types without having full access to everything a concrete `Reflect` type can do. This would help bridge the gap between the current state of the crate and the implementation of that RFC. All that said, this is still a viable solution. If the community believes this is the better path forward, then we can do that instead. These were just my reasons for not initially going with it in this PR. #### Alternative: The Type Registry Approach The `Proxy` trait is great and all, but how does it solve the original problem? Well, it doesn't— yet! The goal would be to start moving information from the derive macro and its attributes to the generated `TypeInfo` since these are known statically and shouldn't change. For example, adding `ignored: bool` to `[Un]NamedField` or a list of impls. However, there is another way of storing this information. This is, of course, one of the uses of the `TypeRegistry`. If we're worried about Dynamic proxies not aligning with their concrete counterparts, we could move more type information to the registry and require its usage. For example, we could replace `Reflect::reflect_hash(&self)` with `Reflect::reflect_hash(&self, registry: &TypeRegistry)`. That's not the _worst_ thing in the world, but it is an ergonomics loss. Additionally, other attributes may have their own requirements, further restricting what's possible without the registry. The `Reflect::apply` method will require the registry as well now. Why? Well because the `map_apply` function used for the `Reflect::apply` impls on `Map` types depends on `Map::insert_boxed`, which (at least for `DynamicMap`) requires `Reflect::reflect_hash`. The same would apply when adding support for reflection-based diffing, which will require `Reflect::reflect_partial_eq`. Again, this is a totally viable alternative. I just chose not to go with it for the reasons above. If we want to go with it, then we can close this PR and we can pursue this alternative instead. #### Downsides Just to highlight a quick potential downside (likely needs more investigation): retrieving the `TypeInfo` requires acquiring a lock on the `GenericTypeInfoCell` used by the `Typed` impls for generic types (non-generic types use a `OnceBox which should be faster). I am not sure how much of a performance hit that is and will need to run some benchmarks to compare against. </details> ### Open Questions 1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be easier for modding? Perhaps, in that case, we need to update `Typed::type_info` and friends as well? 2. Are the alternatives better than the approach this PR takes? Are there other alternatives? --- ## Changelog ### Changed - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` - This method now returns `Option<&'static TypeInfo>` rather than just `&'static TypeInfo` ### Added - Added `Reflect::is_dynamic` method to indicate when a type is dynamic - Added a `set_represented_type` method on all dynamic types ### Removed - Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead) - Removed `Typed` impls for all dynamic types ## Migration Guide - The Dynamic types no longer take a string type name. Instead, they require a static reference to `TypeInfo`: ```rust #[derive(Reflect)] struct MyTupleStruct(f32, f32); let mut dyn_tuple_struct = DynamicTupleStruct::default(); dyn_tuple_struct.insert(1.23_f32); dyn_tuple_struct.insert(3.21_f32); // BEFORE: let type_name = std::any::type_name::<MyTupleStruct>(); dyn_tuple_struct.set_name(type_name); // AFTER: let type_info = <MyTupleStruct as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); ``` - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` and now also returns an `Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`): ```rust // BEFORE: let info: &'static TypeInfo = value.get_type_info(); // AFTER: let info: &'static TypeInfo = value.represented_type_info().unwrap(); ``` - `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use `Reflect::is_dynamic` instead: ```rust // BEFORE: if matches!(value.get_type_info(), TypeInfo::Dynamic) { // ... } // AFTER: if value.is_dynamic() { // ... } ``` --------- Co-authored-by: radiish <cb.setho@gmail.com>
2023-04-26 12:17:46 +00:00
self.represented_type = represented_type;
}
}
impl Reflect for DynamicArray {
#[inline]
fn type_name(&self) -> &str {
bevy_reflect: Better proxies (#6971) # Objective > This PR is based on discussion from #6601 The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as both: 1. Dynamic containers which may hold any arbitrary data 2. Proxy types which may represent any other type Currently, the only way we can represent the proxy-ness of a Dynamic is by giving it a name. ```rust // This is just a dynamic container let mut data = DynamicStruct::default(); // This is a "proxy" data.set_name(std::any::type_name::<Foo>()); ``` This type name is the only way we check that the given Dynamic is a proxy of some other type. When we need to "assert the type" of a `dyn Reflect`, we call `Reflect::type_name` on it. However, because we're only using a string to denote the type, we run into a few gotchas and limitations. For example, hashing a Dynamic proxy may work differently than the type it proxies: ```rust #[derive(Reflect, Hash)] #[reflect(Hash)] struct Foo(i32); let concrete = Foo(123); let dynamic = concrete.clone_dynamic(); let concrete_hash = concrete.reflect_hash(); let dynamic_hash = dynamic.reflect_hash(); // The hashes are not equal because `concrete` uses its own `Hash` impl // while `dynamic` uses a reflection-based hashing algorithm assert_ne!(concrete_hash, dynamic_hash); ``` Because the Dynamic proxy only knows about the name of the type, it's unaware of any other information about it. This means it also differs on `Reflect::reflect_partial_eq`, and may include ignored or skipped fields in places the concrete type wouldn't. ## Solution Rather than having Dynamics pass along just the type name of proxied types, we can instead have them pass around the `TypeInfo`. Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than a `String`: ```diff pub struct DynamicTupleStruct { - type_name: String, + represented_type: Option<&'static TypeInfo>, fields: Vec<Box<dyn Reflect>>, } ``` By changing `Reflect::get_type_info` to `Reflect::represented_type_info`, hopefully we make this behavior a little clearer. And to account for `None` values on these dynamic types, `Reflect::represented_type_info` now returns `Option<&'static TypeInfo>`. ```rust let mut data = DynamicTupleStruct::default(); // Not proxying any specific type assert!(dyn_tuple_struct.represented_type_info().is_none()); let type_info = <Foo as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); // Alternatively: // let dyn_tuple_struct = foo.clone_dynamic(); // Now we're proxying `Foo` assert!(dyn_tuple_struct.represented_type_info().is_some()); ``` This means that we can have full access to all the static type information for the proxied type. Future work would include transitioning more static type information (trait impls, attributes, etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic proxies. ### Alternatives & Rationale > **Note** > These alternatives were written when this PR was first made using a `Proxy` trait. This trait has since been removed. <details> <summary>View</summary> #### Alternative: The `Proxy<T>` Approach I had considered adding something like a `Proxy<T>` type where `T` would be the Dynamic and would contain the proxied type information. This was nice in that it allows us to explicitly determine whether something is a proxy or not at a type level. `Proxy<DynamicStruct>` proxies a struct. Makes sense. The reason I didn't go with this approach is because (1) tuples, (2) complexity, and (3) `PartialReflect`. The `DynamicTuple` struct allows us to represent tuples at runtime. It also allows us to do something you normally can't with tuples: add new fields. Because of this, adding a field immediately invalidates the proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32, NewField)`). By going with this PR's approach, we can just remove the type info on `DynamicTuple` when that happens. However, with the `Proxy<T>` approach, it becomes difficult to represent this behavior— we'd have to completely control how we access data for `T` for each `T`. Secondly, it introduces some added complexities (aside from the manual impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we want to represent it as `dyn Reflect`. What `TypeInfo` do we give it? How would we forward reflection methods to the inner type (remember, we don't have specialization)? How do we separate this from Dynamic types? And finally, how do all this in a way that's both logical and intuitive for users? Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is actually more inline with the [Unique Reflect RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy` trait is really one part of the `PartialReflect` trait introduced in that RFC (it's technically not in that RFC but it fits well with it), where the `PartialReflect` serves as a way for proxies to work _like_ concrete types without having full access to everything a concrete `Reflect` type can do. This would help bridge the gap between the current state of the crate and the implementation of that RFC. All that said, this is still a viable solution. If the community believes this is the better path forward, then we can do that instead. These were just my reasons for not initially going with it in this PR. #### Alternative: The Type Registry Approach The `Proxy` trait is great and all, but how does it solve the original problem? Well, it doesn't— yet! The goal would be to start moving information from the derive macro and its attributes to the generated `TypeInfo` since these are known statically and shouldn't change. For example, adding `ignored: bool` to `[Un]NamedField` or a list of impls. However, there is another way of storing this information. This is, of course, one of the uses of the `TypeRegistry`. If we're worried about Dynamic proxies not aligning with their concrete counterparts, we could move more type information to the registry and require its usage. For example, we could replace `Reflect::reflect_hash(&self)` with `Reflect::reflect_hash(&self, registry: &TypeRegistry)`. That's not the _worst_ thing in the world, but it is an ergonomics loss. Additionally, other attributes may have their own requirements, further restricting what's possible without the registry. The `Reflect::apply` method will require the registry as well now. Why? Well because the `map_apply` function used for the `Reflect::apply` impls on `Map` types depends on `Map::insert_boxed`, which (at least for `DynamicMap`) requires `Reflect::reflect_hash`. The same would apply when adding support for reflection-based diffing, which will require `Reflect::reflect_partial_eq`. Again, this is a totally viable alternative. I just chose not to go with it for the reasons above. If we want to go with it, then we can close this PR and we can pursue this alternative instead. #### Downsides Just to highlight a quick potential downside (likely needs more investigation): retrieving the `TypeInfo` requires acquiring a lock on the `GenericTypeInfoCell` used by the `Typed` impls for generic types (non-generic types use a `OnceBox which should be faster). I am not sure how much of a performance hit that is and will need to run some benchmarks to compare against. </details> ### Open Questions 1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be easier for modding? Perhaps, in that case, we need to update `Typed::type_info` and friends as well? 2. Are the alternatives better than the approach this PR takes? Are there other alternatives? --- ## Changelog ### Changed - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` - This method now returns `Option<&'static TypeInfo>` rather than just `&'static TypeInfo` ### Added - Added `Reflect::is_dynamic` method to indicate when a type is dynamic - Added a `set_represented_type` method on all dynamic types ### Removed - Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead) - Removed `Typed` impls for all dynamic types ## Migration Guide - The Dynamic types no longer take a string type name. Instead, they require a static reference to `TypeInfo`: ```rust #[derive(Reflect)] struct MyTupleStruct(f32, f32); let mut dyn_tuple_struct = DynamicTupleStruct::default(); dyn_tuple_struct.insert(1.23_f32); dyn_tuple_struct.insert(3.21_f32); // BEFORE: let type_name = std::any::type_name::<MyTupleStruct>(); dyn_tuple_struct.set_name(type_name); // AFTER: let type_info = <MyTupleStruct as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); ``` - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` and now also returns an `Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`): ```rust // BEFORE: let info: &'static TypeInfo = value.get_type_info(); // AFTER: let info: &'static TypeInfo = value.represented_type_info().unwrap(); ``` - `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use `Reflect::is_dynamic` instead: ```rust // BEFORE: if matches!(value.get_type_info(), TypeInfo::Dynamic) { // ... } // AFTER: if value.is_dynamic() { // ... } ``` --------- Co-authored-by: radiish <cb.setho@gmail.com>
2023-04-26 12:17:46 +00:00
self.represented_type
.map(|info| info.type_name())
.unwrap_or_else(|| std::any::type_name::<Self>())
}
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::new::<T>()]; let info = TupleStructInfo::new::<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 (aa5178e7736a6f8252e10e543e52722107649d3f) and main (c309acd4322b1c3b2089e247a2d28b938eb7b56d). <details> <summary>See More</summary> The test project included 250 of the following structs (as well as a few other structs): ```rust #[derive(Default)] #[cfg_attr(feature = "reflect", derive(Reflect))] #[cfg_attr(feature = "from_reflect", derive(FromReflect))] pub struct Big001 { inventory: Inventory, foo: usize, bar: String, baz: ItemDescriptor, items: [Item; 20], hello: Option<String>, world: HashMap<i32, String>, okay: (isize, usize, /* wesize */), nope: ((String, String), (f32, f32)), blah: Cow<'static, str>, } ``` > I don't know if the compiler can optimize all these duplicate structs away, but I think it's fine either way. We're comparing times, not finding the absolute worst-case time. I only ran each build 3 times using `cargo build --timings` (thank you @devil-ira), each of which were preceeded by a `cargo clean --package bevy_reflect_compile_test`. Here are the times I got: | Test | Test 1 | Test 2 | Test 3 | Average | | -------------------------------- | ------ | ------ | ------ | ------- | | Main | 1.7s | 3.1s | 1.9s | 2.33s | | Main + `Reflect` | 8.3s | 8.6s | 8.1s | 8.33s | | Main + `Reflect` + `FromReflect` | 11.6s | 11.8s | 13.8s | 12.4s | | PR | 3.5s | 1.8s | 1.9s | 2.4s | | PR + `Reflect` | 9.2s | 8.8s | 9.3s | 9.1s | | PR + `Reflect` + `FromReflect` | 12.9s | 12.3s | 12.5s | 12.56s | </details> --- ## Future Work Even though everything could probably be made `const`, we unfortunately can't. This is because `TypeId::of::<T>()` is not yet `const` (see https://github.com/rust-lang/rust/issues/77125). When it does get stabilized, it would probably be worth coming back and making things `const`. Co-authored-by: MrGVSV <49806985+MrGVSV@users.noreply.github.com>
2022-06-09 21:18:15 +00:00
#[inline]
bevy_reflect: Better proxies (#6971) # Objective > This PR is based on discussion from #6601 The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as both: 1. Dynamic containers which may hold any arbitrary data 2. Proxy types which may represent any other type Currently, the only way we can represent the proxy-ness of a Dynamic is by giving it a name. ```rust // This is just a dynamic container let mut data = DynamicStruct::default(); // This is a "proxy" data.set_name(std::any::type_name::<Foo>()); ``` This type name is the only way we check that the given Dynamic is a proxy of some other type. When we need to "assert the type" of a `dyn Reflect`, we call `Reflect::type_name` on it. However, because we're only using a string to denote the type, we run into a few gotchas and limitations. For example, hashing a Dynamic proxy may work differently than the type it proxies: ```rust #[derive(Reflect, Hash)] #[reflect(Hash)] struct Foo(i32); let concrete = Foo(123); let dynamic = concrete.clone_dynamic(); let concrete_hash = concrete.reflect_hash(); let dynamic_hash = dynamic.reflect_hash(); // The hashes are not equal because `concrete` uses its own `Hash` impl // while `dynamic` uses a reflection-based hashing algorithm assert_ne!(concrete_hash, dynamic_hash); ``` Because the Dynamic proxy only knows about the name of the type, it's unaware of any other information about it. This means it also differs on `Reflect::reflect_partial_eq`, and may include ignored or skipped fields in places the concrete type wouldn't. ## Solution Rather than having Dynamics pass along just the type name of proxied types, we can instead have them pass around the `TypeInfo`. Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than a `String`: ```diff pub struct DynamicTupleStruct { - type_name: String, + represented_type: Option<&'static TypeInfo>, fields: Vec<Box<dyn Reflect>>, } ``` By changing `Reflect::get_type_info` to `Reflect::represented_type_info`, hopefully we make this behavior a little clearer. And to account for `None` values on these dynamic types, `Reflect::represented_type_info` now returns `Option<&'static TypeInfo>`. ```rust let mut data = DynamicTupleStruct::default(); // Not proxying any specific type assert!(dyn_tuple_struct.represented_type_info().is_none()); let type_info = <Foo as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); // Alternatively: // let dyn_tuple_struct = foo.clone_dynamic(); // Now we're proxying `Foo` assert!(dyn_tuple_struct.represented_type_info().is_some()); ``` This means that we can have full access to all the static type information for the proxied type. Future work would include transitioning more static type information (trait impls, attributes, etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic proxies. ### Alternatives & Rationale > **Note** > These alternatives were written when this PR was first made using a `Proxy` trait. This trait has since been removed. <details> <summary>View</summary> #### Alternative: The `Proxy<T>` Approach I had considered adding something like a `Proxy<T>` type where `T` would be the Dynamic and would contain the proxied type information. This was nice in that it allows us to explicitly determine whether something is a proxy or not at a type level. `Proxy<DynamicStruct>` proxies a struct. Makes sense. The reason I didn't go with this approach is because (1) tuples, (2) complexity, and (3) `PartialReflect`. The `DynamicTuple` struct allows us to represent tuples at runtime. It also allows us to do something you normally can't with tuples: add new fields. Because of this, adding a field immediately invalidates the proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32, NewField)`). By going with this PR's approach, we can just remove the type info on `DynamicTuple` when that happens. However, with the `Proxy<T>` approach, it becomes difficult to represent this behavior— we'd have to completely control how we access data for `T` for each `T`. Secondly, it introduces some added complexities (aside from the manual impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we want to represent it as `dyn Reflect`. What `TypeInfo` do we give it? How would we forward reflection methods to the inner type (remember, we don't have specialization)? How do we separate this from Dynamic types? And finally, how do all this in a way that's both logical and intuitive for users? Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is actually more inline with the [Unique Reflect RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy` trait is really one part of the `PartialReflect` trait introduced in that RFC (it's technically not in that RFC but it fits well with it), where the `PartialReflect` serves as a way for proxies to work _like_ concrete types without having full access to everything a concrete `Reflect` type can do. This would help bridge the gap between the current state of the crate and the implementation of that RFC. All that said, this is still a viable solution. If the community believes this is the better path forward, then we can do that instead. These were just my reasons for not initially going with it in this PR. #### Alternative: The Type Registry Approach The `Proxy` trait is great and all, but how does it solve the original problem? Well, it doesn't— yet! The goal would be to start moving information from the derive macro and its attributes to the generated `TypeInfo` since these are known statically and shouldn't change. For example, adding `ignored: bool` to `[Un]NamedField` or a list of impls. However, there is another way of storing this information. This is, of course, one of the uses of the `TypeRegistry`. If we're worried about Dynamic proxies not aligning with their concrete counterparts, we could move more type information to the registry and require its usage. For example, we could replace `Reflect::reflect_hash(&self)` with `Reflect::reflect_hash(&self, registry: &TypeRegistry)`. That's not the _worst_ thing in the world, but it is an ergonomics loss. Additionally, other attributes may have their own requirements, further restricting what's possible without the registry. The `Reflect::apply` method will require the registry as well now. Why? Well because the `map_apply` function used for the `Reflect::apply` impls on `Map` types depends on `Map::insert_boxed`, which (at least for `DynamicMap`) requires `Reflect::reflect_hash`. The same would apply when adding support for reflection-based diffing, which will require `Reflect::reflect_partial_eq`. Again, this is a totally viable alternative. I just chose not to go with it for the reasons above. If we want to go with it, then we can close this PR and we can pursue this alternative instead. #### Downsides Just to highlight a quick potential downside (likely needs more investigation): retrieving the `TypeInfo` requires acquiring a lock on the `GenericTypeInfoCell` used by the `Typed` impls for generic types (non-generic types use a `OnceBox which should be faster). I am not sure how much of a performance hit that is and will need to run some benchmarks to compare against. </details> ### Open Questions 1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be easier for modding? Perhaps, in that case, we need to update `Typed::type_info` and friends as well? 2. Are the alternatives better than the approach this PR takes? Are there other alternatives? --- ## Changelog ### Changed - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` - This method now returns `Option<&'static TypeInfo>` rather than just `&'static TypeInfo` ### Added - Added `Reflect::is_dynamic` method to indicate when a type is dynamic - Added a `set_represented_type` method on all dynamic types ### Removed - Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead) - Removed `Typed` impls for all dynamic types ## Migration Guide - The Dynamic types no longer take a string type name. Instead, they require a static reference to `TypeInfo`: ```rust #[derive(Reflect)] struct MyTupleStruct(f32, f32); let mut dyn_tuple_struct = DynamicTupleStruct::default(); dyn_tuple_struct.insert(1.23_f32); dyn_tuple_struct.insert(3.21_f32); // BEFORE: let type_name = std::any::type_name::<MyTupleStruct>(); dyn_tuple_struct.set_name(type_name); // AFTER: let type_info = <MyTupleStruct as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); ``` - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` and now also returns an `Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`): ```rust // BEFORE: let info: &'static TypeInfo = value.get_type_info(); // AFTER: let info: &'static TypeInfo = value.represented_type_info().unwrap(); ``` - `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use `Reflect::is_dynamic` instead: ```rust // BEFORE: if matches!(value.get_type_info(), TypeInfo::Dynamic) { // ... } // AFTER: if value.is_dynamic() { // ... } ``` --------- Co-authored-by: radiish <cb.setho@gmail.com>
2023-04-26 12:17:46 +00:00
fn get_represented_type_info(&self) -> Option<&'static TypeInfo> {
self.represented_type
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::new::<T>()]; let info = TupleStructInfo::new::<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 (aa5178e7736a6f8252e10e543e52722107649d3f) and main (c309acd4322b1c3b2089e247a2d28b938eb7b56d). <details> <summary>See More</summary> The test project included 250 of the following structs (as well as a few other structs): ```rust #[derive(Default)] #[cfg_attr(feature = "reflect", derive(Reflect))] #[cfg_attr(feature = "from_reflect", derive(FromReflect))] pub struct Big001 { inventory: Inventory, foo: usize, bar: String, baz: ItemDescriptor, items: [Item; 20], hello: Option<String>, world: HashMap<i32, String>, okay: (isize, usize, /* wesize */), nope: ((String, String), (f32, f32)), blah: Cow<'static, str>, } ``` > I don't know if the compiler can optimize all these duplicate structs away, but I think it's fine either way. We're comparing times, not finding the absolute worst-case time. I only ran each build 3 times using `cargo build --timings` (thank you @devil-ira), each of which were preceeded by a `cargo clean --package bevy_reflect_compile_test`. Here are the times I got: | Test | Test 1 | Test 2 | Test 3 | Average | | -------------------------------- | ------ | ------ | ------ | ------- | | Main | 1.7s | 3.1s | 1.9s | 2.33s | | Main + `Reflect` | 8.3s | 8.6s | 8.1s | 8.33s | | Main + `Reflect` + `FromReflect` | 11.6s | 11.8s | 13.8s | 12.4s | | PR | 3.5s | 1.8s | 1.9s | 2.4s | | PR + `Reflect` | 9.2s | 8.8s | 9.3s | 9.1s | | PR + `Reflect` + `FromReflect` | 12.9s | 12.3s | 12.5s | 12.56s | </details> --- ## Future Work Even though everything could probably be made `const`, we unfortunately can't. This is because `TypeId::of::<T>()` is not yet `const` (see https://github.com/rust-lang/rust/issues/77125). When it does get stabilized, it would probably be worth coming back and making things `const`. Co-authored-by: MrGVSV <49806985+MrGVSV@users.noreply.github.com>
2022-06-09 21:18:15 +00:00
}
#[inline]
fn into_any(self: Box<Self>) -> Box<dyn Any> {
self
}
#[inline]
fn as_any(&self) -> &dyn Any {
self
}
#[inline]
fn as_any_mut(&mut self) -> &mut dyn Any {
self
}
#[inline]
fn into_reflect(self: Box<Self>) -> Box<dyn Reflect> {
self
}
#[inline]
fn as_reflect(&self) -> &dyn Reflect {
self
}
#[inline]
fn as_reflect_mut(&mut self) -> &mut dyn Reflect {
self
}
fn apply(&mut self, value: &dyn Reflect) {
array_apply(self, value);
}
#[inline]
fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>> {
*self = value.take()?;
Ok(())
}
#[inline]
fn reflect_ref(&self) -> ReflectRef {
ReflectRef::Array(self)
}
#[inline]
fn reflect_mut(&mut self) -> ReflectMut {
ReflectMut::Array(self)
}
#[inline]
fn reflect_owned(self: Box<Self>) -> ReflectOwned {
ReflectOwned::Array(self)
}
#[inline]
fn clone_value(&self) -> Box<dyn Reflect> {
Box::new(self.clone_dynamic())
}
#[inline]
fn reflect_hash(&self) -> Option<u64> {
array_hash(self)
}
fn reflect_partial_eq(&self, value: &dyn Reflect) -> Option<bool> {
array_partial_eq(self, value)
}
bevy_reflect: Better proxies (#6971) # Objective > This PR is based on discussion from #6601 The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as both: 1. Dynamic containers which may hold any arbitrary data 2. Proxy types which may represent any other type Currently, the only way we can represent the proxy-ness of a Dynamic is by giving it a name. ```rust // This is just a dynamic container let mut data = DynamicStruct::default(); // This is a "proxy" data.set_name(std::any::type_name::<Foo>()); ``` This type name is the only way we check that the given Dynamic is a proxy of some other type. When we need to "assert the type" of a `dyn Reflect`, we call `Reflect::type_name` on it. However, because we're only using a string to denote the type, we run into a few gotchas and limitations. For example, hashing a Dynamic proxy may work differently than the type it proxies: ```rust #[derive(Reflect, Hash)] #[reflect(Hash)] struct Foo(i32); let concrete = Foo(123); let dynamic = concrete.clone_dynamic(); let concrete_hash = concrete.reflect_hash(); let dynamic_hash = dynamic.reflect_hash(); // The hashes are not equal because `concrete` uses its own `Hash` impl // while `dynamic` uses a reflection-based hashing algorithm assert_ne!(concrete_hash, dynamic_hash); ``` Because the Dynamic proxy only knows about the name of the type, it's unaware of any other information about it. This means it also differs on `Reflect::reflect_partial_eq`, and may include ignored or skipped fields in places the concrete type wouldn't. ## Solution Rather than having Dynamics pass along just the type name of proxied types, we can instead have them pass around the `TypeInfo`. Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than a `String`: ```diff pub struct DynamicTupleStruct { - type_name: String, + represented_type: Option<&'static TypeInfo>, fields: Vec<Box<dyn Reflect>>, } ``` By changing `Reflect::get_type_info` to `Reflect::represented_type_info`, hopefully we make this behavior a little clearer. And to account for `None` values on these dynamic types, `Reflect::represented_type_info` now returns `Option<&'static TypeInfo>`. ```rust let mut data = DynamicTupleStruct::default(); // Not proxying any specific type assert!(dyn_tuple_struct.represented_type_info().is_none()); let type_info = <Foo as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); // Alternatively: // let dyn_tuple_struct = foo.clone_dynamic(); // Now we're proxying `Foo` assert!(dyn_tuple_struct.represented_type_info().is_some()); ``` This means that we can have full access to all the static type information for the proxied type. Future work would include transitioning more static type information (trait impls, attributes, etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic proxies. ### Alternatives & Rationale > **Note** > These alternatives were written when this PR was first made using a `Proxy` trait. This trait has since been removed. <details> <summary>View</summary> #### Alternative: The `Proxy<T>` Approach I had considered adding something like a `Proxy<T>` type where `T` would be the Dynamic and would contain the proxied type information. This was nice in that it allows us to explicitly determine whether something is a proxy or not at a type level. `Proxy<DynamicStruct>` proxies a struct. Makes sense. The reason I didn't go with this approach is because (1) tuples, (2) complexity, and (3) `PartialReflect`. The `DynamicTuple` struct allows us to represent tuples at runtime. It also allows us to do something you normally can't with tuples: add new fields. Because of this, adding a field immediately invalidates the proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32, NewField)`). By going with this PR's approach, we can just remove the type info on `DynamicTuple` when that happens. However, with the `Proxy<T>` approach, it becomes difficult to represent this behavior— we'd have to completely control how we access data for `T` for each `T`. Secondly, it introduces some added complexities (aside from the manual impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we want to represent it as `dyn Reflect`. What `TypeInfo` do we give it? How would we forward reflection methods to the inner type (remember, we don't have specialization)? How do we separate this from Dynamic types? And finally, how do all this in a way that's both logical and intuitive for users? Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is actually more inline with the [Unique Reflect RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy` trait is really one part of the `PartialReflect` trait introduced in that RFC (it's technically not in that RFC but it fits well with it), where the `PartialReflect` serves as a way for proxies to work _like_ concrete types without having full access to everything a concrete `Reflect` type can do. This would help bridge the gap between the current state of the crate and the implementation of that RFC. All that said, this is still a viable solution. If the community believes this is the better path forward, then we can do that instead. These were just my reasons for not initially going with it in this PR. #### Alternative: The Type Registry Approach The `Proxy` trait is great and all, but how does it solve the original problem? Well, it doesn't— yet! The goal would be to start moving information from the derive macro and its attributes to the generated `TypeInfo` since these are known statically and shouldn't change. For example, adding `ignored: bool` to `[Un]NamedField` or a list of impls. However, there is another way of storing this information. This is, of course, one of the uses of the `TypeRegistry`. If we're worried about Dynamic proxies not aligning with their concrete counterparts, we could move more type information to the registry and require its usage. For example, we could replace `Reflect::reflect_hash(&self)` with `Reflect::reflect_hash(&self, registry: &TypeRegistry)`. That's not the _worst_ thing in the world, but it is an ergonomics loss. Additionally, other attributes may have their own requirements, further restricting what's possible without the registry. The `Reflect::apply` method will require the registry as well now. Why? Well because the `map_apply` function used for the `Reflect::apply` impls on `Map` types depends on `Map::insert_boxed`, which (at least for `DynamicMap`) requires `Reflect::reflect_hash`. The same would apply when adding support for reflection-based diffing, which will require `Reflect::reflect_partial_eq`. Again, this is a totally viable alternative. I just chose not to go with it for the reasons above. If we want to go with it, then we can close this PR and we can pursue this alternative instead. #### Downsides Just to highlight a quick potential downside (likely needs more investigation): retrieving the `TypeInfo` requires acquiring a lock on the `GenericTypeInfoCell` used by the `Typed` impls for generic types (non-generic types use a `OnceBox which should be faster). I am not sure how much of a performance hit that is and will need to run some benchmarks to compare against. </details> ### Open Questions 1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be easier for modding? Perhaps, in that case, we need to update `Typed::type_info` and friends as well? 2. Are the alternatives better than the approach this PR takes? Are there other alternatives? --- ## Changelog ### Changed - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` - This method now returns `Option<&'static TypeInfo>` rather than just `&'static TypeInfo` ### Added - Added `Reflect::is_dynamic` method to indicate when a type is dynamic - Added a `set_represented_type` method on all dynamic types ### Removed - Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead) - Removed `Typed` impls for all dynamic types ## Migration Guide - The Dynamic types no longer take a string type name. Instead, they require a static reference to `TypeInfo`: ```rust #[derive(Reflect)] struct MyTupleStruct(f32, f32); let mut dyn_tuple_struct = DynamicTupleStruct::default(); dyn_tuple_struct.insert(1.23_f32); dyn_tuple_struct.insert(3.21_f32); // BEFORE: let type_name = std::any::type_name::<MyTupleStruct>(); dyn_tuple_struct.set_name(type_name); // AFTER: let type_info = <MyTupleStruct as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); ``` - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` and now also returns an `Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`): ```rust // BEFORE: let info: &'static TypeInfo = value.get_type_info(); // AFTER: let info: &'static TypeInfo = value.represented_type_info().unwrap(); ``` - `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use `Reflect::is_dynamic` instead: ```rust // BEFORE: if matches!(value.get_type_info(), TypeInfo::Dynamic) { // ... } // AFTER: if value.is_dynamic() { // ... } ``` --------- Co-authored-by: radiish <cb.setho@gmail.com>
2023-04-26 12:17:46 +00:00
#[inline]
fn is_dynamic(&self) -> bool {
true
}
}
impl Array for DynamicArray {
#[inline]
fn get(&self, index: usize) -> Option<&dyn Reflect> {
self.values.get(index).map(|value| &**value)
}
#[inline]
fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {
self.values.get_mut(index).map(|value| &mut **value)
}
#[inline]
fn len(&self) -> usize {
self.values.len()
}
#[inline]
fn iter(&self) -> ArrayIter {
ArrayIter::new(self)
}
bevy_reflect: Get owned fields (#5728) # Objective Sometimes it's useful to be able to retrieve all the fields of a container type so that they may be processed separately. With reflection, however, we typically only have access to references. The only alternative is to "clone" the value using `Reflect::clone_value`. This, however, returns a Dynamic type in most cases. The solution there would be to use `FromReflect` instead, but this also has a problem in that it means we need to add `FromReflect` as an additional bound. ## Solution Add a `drain` method to all container traits. This returns a `Vec<Box<dyn Reflect>>` (except for `Map` which returns `Vec<(Box<dyn Reflect>, Box<dyn Reflect>)>`). This allows us to do things a lot simpler. For example, if we finished processing a struct and just need a particular value: ```rust // === OLD === // /// May or may not return a Dynamic*** value (even if `container` wasn't a `DynamicStruct`) fn get_output(container: Box<dyn Struct>, output_index: usize) -> Box<dyn Reflect> { container.field_at(output_index).unwrap().clone_value() } // === NEW === // /// Returns _exactly_ whatever was in the given struct fn get_output(container: Box<dyn Struct>, output_index: usize) -> Box<dyn Reflect> { container.drain().remove(output_index).unwrap() } ``` ### Discussion * Is `drain` the best method name? It makes sense that it "drains" all the fields and that it consumes the container in the process, but I'm open to alternatives. --- ## Changelog * Added a `drain` method to the following traits: * `Struct` * `TupleStruct` * `Tuple` * `Array` * `List` * `Map` * `Enum`
2022-08-30 21:20:58 +00:00
#[inline]
fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {
self.values.into_vec()
}
#[inline]
fn clone_dynamic(&self) -> DynamicArray {
DynamicArray {
bevy_reflect: Better proxies (#6971) # Objective > This PR is based on discussion from #6601 The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as both: 1. Dynamic containers which may hold any arbitrary data 2. Proxy types which may represent any other type Currently, the only way we can represent the proxy-ness of a Dynamic is by giving it a name. ```rust // This is just a dynamic container let mut data = DynamicStruct::default(); // This is a "proxy" data.set_name(std::any::type_name::<Foo>()); ``` This type name is the only way we check that the given Dynamic is a proxy of some other type. When we need to "assert the type" of a `dyn Reflect`, we call `Reflect::type_name` on it. However, because we're only using a string to denote the type, we run into a few gotchas and limitations. For example, hashing a Dynamic proxy may work differently than the type it proxies: ```rust #[derive(Reflect, Hash)] #[reflect(Hash)] struct Foo(i32); let concrete = Foo(123); let dynamic = concrete.clone_dynamic(); let concrete_hash = concrete.reflect_hash(); let dynamic_hash = dynamic.reflect_hash(); // The hashes are not equal because `concrete` uses its own `Hash` impl // while `dynamic` uses a reflection-based hashing algorithm assert_ne!(concrete_hash, dynamic_hash); ``` Because the Dynamic proxy only knows about the name of the type, it's unaware of any other information about it. This means it also differs on `Reflect::reflect_partial_eq`, and may include ignored or skipped fields in places the concrete type wouldn't. ## Solution Rather than having Dynamics pass along just the type name of proxied types, we can instead have them pass around the `TypeInfo`. Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than a `String`: ```diff pub struct DynamicTupleStruct { - type_name: String, + represented_type: Option<&'static TypeInfo>, fields: Vec<Box<dyn Reflect>>, } ``` By changing `Reflect::get_type_info` to `Reflect::represented_type_info`, hopefully we make this behavior a little clearer. And to account for `None` values on these dynamic types, `Reflect::represented_type_info` now returns `Option<&'static TypeInfo>`. ```rust let mut data = DynamicTupleStruct::default(); // Not proxying any specific type assert!(dyn_tuple_struct.represented_type_info().is_none()); let type_info = <Foo as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); // Alternatively: // let dyn_tuple_struct = foo.clone_dynamic(); // Now we're proxying `Foo` assert!(dyn_tuple_struct.represented_type_info().is_some()); ``` This means that we can have full access to all the static type information for the proxied type. Future work would include transitioning more static type information (trait impls, attributes, etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic proxies. ### Alternatives & Rationale > **Note** > These alternatives were written when this PR was first made using a `Proxy` trait. This trait has since been removed. <details> <summary>View</summary> #### Alternative: The `Proxy<T>` Approach I had considered adding something like a `Proxy<T>` type where `T` would be the Dynamic and would contain the proxied type information. This was nice in that it allows us to explicitly determine whether something is a proxy or not at a type level. `Proxy<DynamicStruct>` proxies a struct. Makes sense. The reason I didn't go with this approach is because (1) tuples, (2) complexity, and (3) `PartialReflect`. The `DynamicTuple` struct allows us to represent tuples at runtime. It also allows us to do something you normally can't with tuples: add new fields. Because of this, adding a field immediately invalidates the proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32, NewField)`). By going with this PR's approach, we can just remove the type info on `DynamicTuple` when that happens. However, with the `Proxy<T>` approach, it becomes difficult to represent this behavior— we'd have to completely control how we access data for `T` for each `T`. Secondly, it introduces some added complexities (aside from the manual impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we want to represent it as `dyn Reflect`. What `TypeInfo` do we give it? How would we forward reflection methods to the inner type (remember, we don't have specialization)? How do we separate this from Dynamic types? And finally, how do all this in a way that's both logical and intuitive for users? Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is actually more inline with the [Unique Reflect RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy` trait is really one part of the `PartialReflect` trait introduced in that RFC (it's technically not in that RFC but it fits well with it), where the `PartialReflect` serves as a way for proxies to work _like_ concrete types without having full access to everything a concrete `Reflect` type can do. This would help bridge the gap between the current state of the crate and the implementation of that RFC. All that said, this is still a viable solution. If the community believes this is the better path forward, then we can do that instead. These were just my reasons for not initially going with it in this PR. #### Alternative: The Type Registry Approach The `Proxy` trait is great and all, but how does it solve the original problem? Well, it doesn't— yet! The goal would be to start moving information from the derive macro and its attributes to the generated `TypeInfo` since these are known statically and shouldn't change. For example, adding `ignored: bool` to `[Un]NamedField` or a list of impls. However, there is another way of storing this information. This is, of course, one of the uses of the `TypeRegistry`. If we're worried about Dynamic proxies not aligning with their concrete counterparts, we could move more type information to the registry and require its usage. For example, we could replace `Reflect::reflect_hash(&self)` with `Reflect::reflect_hash(&self, registry: &TypeRegistry)`. That's not the _worst_ thing in the world, but it is an ergonomics loss. Additionally, other attributes may have their own requirements, further restricting what's possible without the registry. The `Reflect::apply` method will require the registry as well now. Why? Well because the `map_apply` function used for the `Reflect::apply` impls on `Map` types depends on `Map::insert_boxed`, which (at least for `DynamicMap`) requires `Reflect::reflect_hash`. The same would apply when adding support for reflection-based diffing, which will require `Reflect::reflect_partial_eq`. Again, this is a totally viable alternative. I just chose not to go with it for the reasons above. If we want to go with it, then we can close this PR and we can pursue this alternative instead. #### Downsides Just to highlight a quick potential downside (likely needs more investigation): retrieving the `TypeInfo` requires acquiring a lock on the `GenericTypeInfoCell` used by the `Typed` impls for generic types (non-generic types use a `OnceBox which should be faster). I am not sure how much of a performance hit that is and will need to run some benchmarks to compare against. </details> ### Open Questions 1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be easier for modding? Perhaps, in that case, we need to update `Typed::type_info` and friends as well? 2. Are the alternatives better than the approach this PR takes? Are there other alternatives? --- ## Changelog ### Changed - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` - This method now returns `Option<&'static TypeInfo>` rather than just `&'static TypeInfo` ### Added - Added `Reflect::is_dynamic` method to indicate when a type is dynamic - Added a `set_represented_type` method on all dynamic types ### Removed - Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead) - Removed `Typed` impls for all dynamic types ## Migration Guide - The Dynamic types no longer take a string type name. Instead, they require a static reference to `TypeInfo`: ```rust #[derive(Reflect)] struct MyTupleStruct(f32, f32); let mut dyn_tuple_struct = DynamicTupleStruct::default(); dyn_tuple_struct.insert(1.23_f32); dyn_tuple_struct.insert(3.21_f32); // BEFORE: let type_name = std::any::type_name::<MyTupleStruct>(); dyn_tuple_struct.set_name(type_name); // AFTER: let type_info = <MyTupleStruct as Typed>::type_info(); dyn_tuple_struct.set_represented_type(Some(type_info)); ``` - `Reflect::get_type_info` has been renamed to `Reflect::represented_type_info` and now also returns an `Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`): ```rust // BEFORE: let info: &'static TypeInfo = value.get_type_info(); // AFTER: let info: &'static TypeInfo = value.represented_type_info().unwrap(); ``` - `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use `Reflect::is_dynamic` instead: ```rust // BEFORE: if matches!(value.get_type_info(), TypeInfo::Dynamic) { // ... } // AFTER: if value.is_dynamic() { // ... } ``` --------- Co-authored-by: radiish <cb.setho@gmail.com>
2023-04-26 12:17:46 +00:00
represented_type: self.represented_type,
values: self
.values
.iter()
.map(|value| value.clone_value())
.collect(),
}
}
}
/// An iterator over an [`Array`].
pub struct ArrayIter<'a> {
array: &'a dyn Array,
index: usize,
}
impl<'a> ArrayIter<'a> {
/// Creates a new [`ArrayIter`].
#[inline]
pub const fn new(array: &'a dyn Array) -> ArrayIter {
ArrayIter { array, index: 0 }
}
}
impl<'a> Iterator for ArrayIter<'a> {
type Item = &'a dyn Reflect;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
let value = self.array.get(self.index);
self.index += 1;
value
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let size = self.array.len();
(size, Some(size))
}
}
impl<'a> ExactSizeIterator for ArrayIter<'a> {}
/// Returns the `u64` hash of the given [array](Array).
#[inline]
pub fn array_hash<A: Array>(array: &A) -> Option<u64> {
let mut hasher = reflect_hasher();
std::any::Any::type_id(array).hash(&mut hasher);
array.len().hash(&mut hasher);
for value in array.iter() {
hasher.write_u64(value.reflect_hash()?);
}
Some(hasher.finish())
}
/// Applies the reflected [array](Array) data to the given [array](Array).
///
/// # Panics
///
/// * Panics if the two arrays have differing lengths.
/// * Panics if the reflected value is not a [valid array](ReflectRef::Array).
///
#[inline]
pub fn array_apply<A: Array>(array: &mut A, reflect: &dyn Reflect) {
if let ReflectRef::Array(reflect_array) = reflect.reflect_ref() {
if array.len() != reflect_array.len() {
panic!("Attempted to apply different sized `Array` types.");
}
for (i, value) in reflect_array.iter().enumerate() {
let v = array.get_mut(i).unwrap();
v.apply(value);
}
} else {
panic!("Attempted to apply a non-`Array` type to an `Array` type.");
}
}
/// Compares two [arrays](Array) (one concrete and one reflected) to see if they
/// are equal.
///
/// Returns [`None`] if the comparison couldn't even be performed.
#[inline]
pub fn array_partial_eq<A: Array>(array: &A, reflect: &dyn Reflect) -> Option<bool> {
match reflect.reflect_ref() {
ReflectRef::Array(reflect_array) if reflect_array.len() == array.len() => {
for (a, b) in array.iter().zip(reflect_array.iter()) {
let eq_result = a.reflect_partial_eq(b);
if let failed @ (Some(false) | None) = eq_result {
return failed;
}
}
}
_ => return Some(false),
}
Some(true)
}
bevy_reflect: Improve debug formatting for reflected types (#4218) # Objective Debugging reflected types can be somewhat frustrating since all `dyn Reflect` trait objects return something like `Reflect(core::option::Option<alloc::string::String>)`. It would be much nicer to be able to see the actual value— or even use a custom `Debug` implementation. ## Solution Added `Reflect::debug` which allows users to customize the debug output. It sets defaults for all `ReflectRef` subtraits and falls back to `Reflect(type_name)` if no `Debug` implementation was registered. To register a custom `Debug` impl, users can add `#[reflect(Debug)]` like they can with other traits. ### Example Using the following structs: ```rust #[derive(Reflect)] pub struct Foo { a: usize, nested: Bar, #[reflect(ignore)] _ignored: NonReflectedValue, } #[derive(Reflect)] pub struct Bar { value: Vec2, tuple_value: (i32, String), list_value: Vec<usize>, // We can't determine debug formatting for Option<T> yet unknown_value: Option<String>, custom_debug: CustomDebug } #[derive(Reflect)] #[reflect(Debug)] struct CustomDebug; impl Debug for CustomDebug { fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result { write!(f, "This is a custom debug!") } } pub struct NonReflectedValue { _a: usize, } ``` We can do: ```rust let value = Foo { a: 1, _ignored: NonReflectedValue { _a: 10 }, nested: Bar { value: Vec2::new(1.23, 3.21), tuple_value: (123, String::from("Hello")), list_value: vec![1, 2, 3], unknown_value: Some(String::from("World")), custom_debug: CustomDebug }, }; let reflected_value: &dyn Reflect = &value; println!("{:#?}", reflected_value) ``` Which results in: ```rust Foo { a: 2, nested: Bar { value: Vec2( 1.23, 3.21, ), tuple_value: ( 123, "Hello", ), list_value: [ 1, 2, 3, ], unknown_value: Reflect(core::option::Option<alloc::string::String>), custom_debug: This is a custom debug!, }, } ``` Notice that neither `Foo` nor `Bar` implement `Debug`, yet we can still deduce it. This might be a concern if we're worried about leaking internal values. If it is, we might want to consider a way to exclude fields (possibly with a `#[reflect(hide)]` macro) or make it purely opt in (as opposed to the default implementation automatically handled by ReflectRef subtraits). Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2022-05-30 16:41:31 +00:00
/// The default debug formatter for [`Array`] types.
///
/// # Example
/// ```
/// use bevy_reflect::Reflect;
///
/// let my_array: &dyn Reflect = &[1, 2, 3];
/// println!("{:#?}", my_array);
///
/// // Output:
///
/// // [
/// // 1,
/// // 2,
/// // 3,
/// // ]
/// ```
#[inline]
pub fn array_debug(dyn_array: &dyn Array, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let mut debug = f.debug_list();
for item in dyn_array.iter() {
debug.entry(&item as &dyn Debug);
}
debug.finish()
}