Sub app label changes (#2717)

Makes some tweaks to the SubApp labeling introduced in #2695:

* Ergonomics improvements
* Removes unnecessary allocation when retrieving subapp label
* Removes the newly added "app macros" crate in favor of bevy_derive
* renamed RenderSubApp to RenderApp

@zicklag (for reference)

crates/bevy_app/Cargo.toml

@@ -23,7 +23,6 @@ bevy_derive = { path = "../bevy_derive", version = "0.5.0" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.5.0" }
 bevy_reflect = { path = "../bevy_reflect", version = "0.5.0", optional = true }
 bevy_utils = { path = "../bevy_utils", version = "0.5.0" }
-bevy_app_macros = { path = "./macros", version = "0.5.0" }
 
 # other
 serde = { version = "1.0", features = ["derive"], optional = true }

crates/bevy_app/macros/Cargo.toml

@@ -1,16 +0,0 @@
-[package]
-name = "bevy_app_macros"
-version = "0.5.0"
-description = "Bevy App Macros"
-edition = "2018"
-license = "MIT OR Apache-2.0"
-
-[lib]
-proc-macro = true
-
-[dependencies]
-bevy_macro_utils = { path = "../../bevy_macro_utils", version = "0.5.0" }
-
-syn = "1.0"
-quote = "1.0"
-proc-macro2 = "1.0"

crates/bevy_app/macros/src/lib.rs

@@ -1,19 +0,0 @@
-extern crate proc_macro;
-
-use bevy_macro_utils::{derive_label, BevyManifest};
-use proc_macro::TokenStream;
-use quote::format_ident;
-
-#[proc_macro_derive(SubAppLabel)]
-pub fn derive_sub_app_label(input: TokenStream) -> TokenStream {
-    let input = syn::parse_macro_input!(input as syn::DeriveInput);
-    let mut trait_path = bevy_app_path();
-    trait_path
-        .segments
-        .push(format_ident!("SubAppLabel").into());
-    derive_label(input, trait_path)
-}
-
-fn bevy_app_path() -> syn::Path {
-    BevyManifest::default().get_path("bevy_app")
-}

crates/bevy_app/src/app.rs

@@ -1,3 +1,5 @@
+pub use bevy_derive::AppLabel;
+
 use crate::{CoreStage, Events, Plugin, PluginGroup, PluginGroupBuilder, StartupStage};
 use bevy_ecs::{
     component::{Component, ComponentDescriptor},
@@ -10,13 +12,10 @@ use bevy_ecs::{
 use bevy_utils::{tracing::debug, HashMap};
 use std::{fmt::Debug, hash::Hash};
 
-pub use bevy_app_macros::SubAppLabel;
-
 #[cfg(feature = "trace")]
 use bevy_utils::tracing::info_span;
 
-bevy_utils::define_label!(SubAppLabel);
-type BoxedSubAppLabel = Box<dyn SubAppLabel>;
+bevy_utils::define_label!(AppLabel);
 
 #[allow(clippy::needless_doctest_main)]
 /// Containers of app logic and data
@@ -45,7 +44,7 @@ pub struct App {
     pub world: World,
     pub runner: Box<dyn Fn(App)>,
     pub schedule: Schedule,
-    sub_apps: HashMap<BoxedSubAppLabel, SubApp>,
+    sub_apps: HashMap<Box<dyn AppLabel>, SubApp>,
 }
 
 struct SubApp {
@@ -594,7 +593,7 @@ impl App {
 
     pub fn add_sub_app(
         &mut self,
-        label: impl SubAppLabel,
+        label: impl AppLabel,
         app: App,
         f: impl Fn(&mut World, &mut App) + 'static,
     ) -> &mut Self {
@@ -608,11 +607,21 @@ impl App {
         self
     }
 
-    pub fn sub_app_mut(&mut self, label: impl SubAppLabel) -> Option<&mut App> {
-        let label = Box::new(label) as BoxedSubAppLabel;
+    /// Retrieves a "sub app" stored inside this [App]. This will panic if the sub app does not exist.
+    pub fn sub_app(&mut self, label: impl AppLabel) -> &mut App {
+        match self.get_sub_app(label) {
+            Ok(app) => app,
+            Err(label) => panic!("Sub-App with label '{:?}' does not exist", label),
+        }
+    }
+
+    /// Retrieves a "sub app" inside this [App] with the given label, if it exists. Otherwise returns
+    /// an [Err] containing the given label.
+    pub fn get_sub_app(&mut self, label: impl AppLabel) -> Result<&mut App, impl AppLabel> {
         self.sub_apps
-            .get_mut(&label)
+            .get_mut((&label) as &dyn AppLabel)
             .map(|sub_app| &mut sub_app.app)
+            .ok_or(label)
     }
 }
 

crates/bevy_derive/src/lib.rs

@@ -10,7 +10,9 @@ mod render_resources;
 mod resource;
 mod shader_defs;
 
+use bevy_macro_utils::{derive_label, BevyManifest};
 use proc_macro::TokenStream;
+use quote::format_ident;
 
 /// Derives the FromResources trait. Each field must also implement the FromResources trait or this
 /// will fail. FromResources is automatically implemented for types that implement Default.
@@ -60,3 +62,11 @@ pub fn bevy_main(attr: TokenStream, item: TokenStream) -> TokenStream {
 pub fn derive_enum_variant_meta(input: TokenStream) -> TokenStream {
     enum_variant_meta::derive_enum_variant_meta(input)
 }
+
+#[proc_macro_derive(AppLabel)]
+pub fn derive_app_label(input: TokenStream) -> TokenStream {
+    let input = syn::parse_macro_input!(input as syn::DeriveInput);
+    let mut trait_path = BevyManifest::default().get_path("bevy_app");
+    trait_path.segments.push(format_ident!("AppLabel").into());
+    derive_label(input, trait_path)
+}

pipelined/bevy_core_pipeline/src/lib.rs

@@ -20,7 +20,7 @@ use bevy_render2::{
     renderer::RenderDevice,
     texture::TextureCache,
     view::{ExtractedView, ViewPlugin},
-    RenderStage, RenderSubApp, RenderWorld,
+    RenderApp, RenderStage, RenderWorld,
 };
 
 /// Resource that configures the clear color
@@ -74,7 +74,7 @@ impl Plugin for CorePipelinePlugin {
     fn build(&self, app: &mut App) {
         app.init_resource::<ClearColor>();
 
-        let render_app = app.sub_app_mut(RenderSubApp).unwrap();
+        let render_app = app.sub_app(RenderApp);
         render_app
             .add_system_to_stage(RenderStage::Extract, extract_clear_color)
             .add_system_to_stage(RenderStage::Extract, extract_core_pipeline_camera_phases)

pipelined/bevy_pbr2/src/lib.rs

@@ -13,7 +13,7 @@ use bevy_ecs::prelude::*;
 use bevy_render2::{
     render_graph::RenderGraph,
     render_phase::{sort_phase_system, DrawFunctions},
-    RenderStage, RenderSubApp,
+    RenderApp, RenderStage,
 };
 
 pub mod draw_3d_graph {
@@ -30,7 +30,7 @@ impl Plugin for PbrPlugin {
         app.add_plugin(StandardMaterialPlugin)
             .init_resource::<AmbientLight>();
 
-        let render_app = app.sub_app_mut(RenderSubApp).unwrap();
+        let render_app = app.sub_app(RenderApp);
         render_app
             .add_system_to_stage(RenderStage::Extract, render::extract_meshes)
             .add_system_to_stage(RenderStage::Extract, render::extract_lights)

pipelined/bevy_render2/src/camera/mod.rs

@@ -12,7 +12,7 @@ pub use bundle::*;
 pub use camera::*;
 pub use projection::*;
 
-use crate::{view::ExtractedView, RenderStage, RenderSubApp};
+use crate::{view::ExtractedView, RenderApp, RenderStage};
 use bevy_app::{App, CoreStage, Plugin};
 use bevy_ecs::prelude::*;
 
@@ -40,8 +40,7 @@ impl Plugin for CameraPlugin {
                 CoreStage::PostUpdate,
                 crate::camera::camera_system::<PerspectiveProjection>,
             );
-        let render_app = app.sub_app_mut(RenderSubApp).unwrap();
-        render_app
+        app.sub_app(RenderApp)
             .init_resource::<ExtractedCameraNames>()
             .add_system_to_stage(RenderStage::Extract, extract_cameras);
     }

pipelined/bevy_render2/src/lib.rs

@@ -24,7 +24,7 @@ use crate::{
     texture::ImagePlugin,
     view::{ViewPlugin, WindowRenderPlugin},
 };
-use bevy_app::{App, Plugin, SubAppLabel};
+use bevy_app::{App, AppLabel, Plugin};
 use bevy_ecs::prelude::*;
 
 #[derive(Default)]
@@ -74,8 +74,8 @@ impl DerefMut for RenderWorld {
 }
 
 /// Label for the rendering sub-app
-#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq, SubAppLabel)]
-pub struct RenderSubApp;
+#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq, AppLabel)]
+pub struct RenderApp;
 
 /// A "scratch" world used to avoid allocating new worlds every frame when
 // swapping out the Render World.
@@ -118,7 +118,7 @@ impl Plugin for RenderPlugin {
             .init_resource::<RenderGraph>()
             .init_resource::<DrawFunctions>();
 
-        app.add_sub_app(RenderSubApp, render_app, move |app_world, render_app| {
+        app.add_sub_app(RenderApp, render_app, move |app_world, render_app| {
             // reserve all existing app entities for use in render_app
             // they can only be spawned using `get_or_spawn()`
             let meta_len = app_world.entities().meta.len();

pipelined/bevy_render2/src/render_asset.rs

@@ -2,7 +2,7 @@ use std::marker::PhantomData;
 
 use crate::{
     renderer::{RenderDevice, RenderQueue},
-    RenderStage, RenderSubApp,
+    RenderApp, RenderStage,
 };
 use bevy_app::{App, Plugin};
 use bevy_asset::{Asset, AssetEvent, Assets, Handle};
@@ -31,8 +31,7 @@ impl<A: RenderAsset> Default for RenderAssetPlugin<A> {
 
 impl<A: RenderAsset> Plugin for RenderAssetPlugin<A> {
     fn build(&self, app: &mut App) {
-        let render_app = app.sub_app_mut(RenderSubApp).unwrap();
-        render_app
+        app.sub_app(RenderApp)
             .init_resource::<ExtractedAssets<A>>()
             .init_resource::<RenderAssets<A>>()
             .add_system_to_stage(RenderStage::Extract, extract_render_asset::<A>)

pipelined/bevy_render2/src/texture/mod.rs

@@ -13,7 +13,7 @@ pub use hdr_texture_loader::*;
 pub use image_texture_loader::*;
 pub use texture_cache::*;
 
-use crate::{render_asset::RenderAssetPlugin, RenderStage, RenderSubApp};
+use crate::{render_asset::RenderAssetPlugin, RenderApp, RenderStage};
 use bevy_app::{App, Plugin};
 use bevy_asset::AddAsset;
 
@@ -30,8 +30,7 @@ impl Plugin for ImagePlugin {
         app.add_plugin(RenderAssetPlugin::<Image>::default())
             .add_asset::<Image>();
 
-        let render_app = app.sub_app_mut(RenderSubApp).unwrap();
-        render_app
+        app.sub_app(RenderApp)
             .init_resource::<TextureCache>()
             .add_system_to_stage(RenderStage::Cleanup, update_texture_cache_system);
     }

pipelined/bevy_render2/src/view/mod.rs

@@ -7,7 +7,7 @@ use crate::{
     render_graph::{Node, NodeRunError, RenderGraph, RenderGraphContext},
     render_resource::DynamicUniformVec,
     renderer::{RenderContext, RenderDevice},
-    RenderStage, RenderSubApp,
+    RenderApp, RenderStage,
 };
 use bevy_app::{App, Plugin};
 use bevy_ecs::prelude::*;
@@ -22,7 +22,7 @@ impl ViewPlugin {
 
 impl Plugin for ViewPlugin {
     fn build(&self, app: &mut App) {
-        let render_app = app.sub_app_mut(RenderSubApp).unwrap();
+        let render_app = app.sub_app(RenderApp);
         render_app
             .init_resource::<ViewMeta>()
             .add_system_to_stage(RenderStage::Prepare, prepare_views);

pipelined/bevy_render2/src/view/window.rs

@@ -2,7 +2,7 @@ use crate::{
     render_resource::TextureView,
     renderer::{RenderDevice, RenderInstance},
     texture::BevyDefault,
-    RenderStage, RenderSubApp,
+    RenderApp, RenderStage,
 };
 use bevy_app::{App, Plugin};
 use bevy_ecs::prelude::*;
@@ -19,8 +19,7 @@ pub struct WindowRenderPlugin;
 
 impl Plugin for WindowRenderPlugin {
     fn build(&self, app: &mut App) {
-        let render_app = app.sub_app_mut(RenderSubApp).unwrap();
-        render_app
+        app.sub_app(RenderApp)
             .init_resource::<WindowSurfaces>()
             .init_resource::<NonSendMarker>()
             .add_system_to_stage(RenderStage::Extract, extract_windows)

pipelined/bevy_sprite2/src/lib.rs

@@ -17,7 +17,7 @@ pub use texture_atlas_builder::*;
 
 use bevy_app::prelude::*;
 use bevy_render2::{
-    render_graph::RenderGraph, render_phase::DrawFunctions, RenderStage, RenderSubApp,
+    render_graph::RenderGraph, render_phase::DrawFunctions, RenderApp, RenderStage,
 };
 
 #[derive(Default)]
@@ -28,7 +28,7 @@ impl Plugin for SpritePlugin {
         app.add_asset::<TextureAtlas>()
             .register_type::<Sprite>()
             .add_system_to_stage(CoreStage::PostUpdate, sprite_auto_resize_system);
-        let render_app = app.sub_app_mut(RenderSubApp).unwrap();
+        let render_app = app.sub_app(RenderApp);
         render_app
             .init_resource::<ExtractedSprites>()
             .add_system_to_stage(RenderStage::Extract, render::extract_atlases)
@@ -44,8 +44,7 @@ impl Plugin for SpritePlugin {
             .unwrap()
             .write()
             .add(draw_sprite);
-        let render_world = app.sub_app_mut(RenderSubApp).unwrap().world.cell();
-        let mut graph = render_world.get_resource_mut::<RenderGraph>().unwrap();
+        let mut graph = render_app.world.get_resource_mut::<RenderGraph>().unwrap();
         graph.add_node("sprite", SpriteNode);
         graph
             .add_node_edge("sprite", bevy_core_pipeline::node::MAIN_PASS_DEPENDENCIES)

tools/publish.sh

@@ -7,7 +7,6 @@ crates=(
     bevy_tasks
     bevy_ecs/macros
     bevy_ecs
-    bevy_app/macros
     bevy_app
     bevy_log
     bevy_dynamic_plugin