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# Objective Fixes #9094 ## Solution Takes a bit from [this](https://github.com/bevyengine/bevy/issues/9094#issuecomment-1629333851) comment as well as a [comment](https://discord.com/channels/691052431525675048/1002362493634629796/1128024873260810271) from @soqb. This allows users to opt-out of the `TypePath` implementation that is automatically generated by the `Reflect` derive macro, allowing custom `TypePath` implementations. ```rust #[derive(Reflect)] #[reflect(type_path = false)] struct Foo<T> { #[reflect(ignore)] _marker: PhantomData<T>, } struct NotTypePath; impl<T: 'static> TypePath for Foo<T> { fn type_path() -> &'static str { std::any::type_name::<Self>() } fn short_type_path() -> &'static str { static CELL: GenericTypePathCell = GenericTypePathCell::new(); CELL.get_or_insert::<Self, _>(|| { bevy_utils::get_short_name(std::any::type_name::<Self>()) }) } fn crate_name() -> Option<&'static str> { Some("my_crate") } fn module_path() -> Option<&'static str> { Some("my_crate::foo") } fn type_ident() -> Option<&'static str> { Some("Foo") } } // Can use `TypePath` let _ = <Foo<NotTypePath> as TypePath>::type_path(); // Can register the type let mut registry = TypeRegistry::default(); registry.register::<Foo<NotTypePath>>(); ``` #### Type Path Stability The stability of type paths mainly come into play during serialization. If a type is moved between builds, an unstable type path may become invalid. Users that opt-out of `TypePath` and rely on something like `std::any::type_name` as in the example above, should be aware that this solution removes the stability guarantees. Deserialization thus expects that type to never move. If it does, then the serialized type paths will need to be updated accordingly. If a user depends on stability, they will need to implement that stability logic manually (probably by looking at the expanded output of a typical `Reflect`/`TypePath` derive). This could be difficult for type parameters that don't/can't implement `TypePath`, and will need to make heavy use of string parsing and manipulation to achieve the same effect (alternatively, they can choose to simply exclude any type parameter that doesn't implement `TypePath`). --- ## Changelog - Added the `#[reflect(type_path = false)]` attribute to opt out of the `TypePath` impl when deriving `Reflect` --------- Co-authored-by: Carter Anderson <mcanders1@gmail.com> |
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