Jakob Hellermann f867319336 add ReflectAsset and ReflectHandle (#5923) ... # Objective  ^ enable this Concretely, I need to - list all handle ids for an asset type - fetch the asset as `dyn Reflect`, given a `HandleUntyped` - when encountering a `Handle<T>`, find out what asset type that handle refers to (`T`'s type id) and turn the handle into a `HandleUntyped` ## Solution - add `ReflectAsset` type containing function pointers for working with assets ```rust pub struct ReflectAsset { type_uuid: Uuid, assets_resource_type_id: TypeId, // TypeId of the `Assets<T>` resource get: fn(&World, HandleUntyped) -> Option<&dyn Reflect>, get_mut: fn(&mut World, HandleUntyped) -> Option<&mut dyn Reflect>, get_unchecked_mut: unsafe fn(&World, HandleUntyped) -> Option<&mut dyn Reflect>, add: fn(&mut World, &dyn Reflect) -> HandleUntyped, set: fn(&mut World, HandleUntyped, &dyn Reflect) -> HandleUntyped, len: fn(&World) -> usize, ids: for<'w> fn(&'w World) -> Box<dyn Iterator<Item = HandleId> + 'w>, remove: fn(&mut World, HandleUntyped) -> Option<Box<dyn Reflect>>, } ``` - add `ReflectHandle` type relating the handle back to the asset type and providing a way to create a `HandleUntyped` ```rust pub struct ReflectHandle { type_uuid: Uuid, asset_type_id: TypeId, downcast_handle_untyped: fn(&dyn Any) -> Option<HandleUntyped>, } ``` - add the corresponding `FromType` impls - add a function `app.register_asset_reflect` which is supposed to be called after `.add_asset` and registers `ReflectAsset` and `ReflectHandle` in the type registry --- ## Changelog - add `ReflectAsset` and `ReflectHandle` types, which allow code to use reflection to manipulate arbitrary assets without knowing their types at compile time		2022-10-28 20:42:33 +00:00
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src	add ReflectAsset and ReflectHandle (#5923)	2022-10-28 20:42:33 +00:00
Cargo.toml	Make Resource trait opt-in, requiring #[derive(Resource)] V2 (#5577)	2022-08-08 21:36:35 +00:00