app: PluginGroups and DefaultPlugins (#744)

Cargo.toml

@@ -154,6 +154,10 @@ path = "examples/app/headless.rs"
 name = "plugin"
 path = "examples/app/plugin.rs"
 
+[[example]]
+name = "plugin_group"
+path = "examples/app/plugin_group.rs"
+
 [[example]]
 name = "return_after_run"
 path = "examples/app/return_after_run.rs"

crates/bevy_app/Cargo.toml

@@ -17,6 +17,7 @@ keywords = ["bevy"]
 bevy_derive = { path = "../bevy_derive", version = "0.2.1" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.2.1" }
 bevy_math = { path = "../bevy_math", version = "0.2.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.2.1" }
 
 # other
 log = { version = "0.4", features = ["release_max_level_info"] }

crates/bevy_app/src/app_builder.rs

@@ -2,7 +2,7 @@ use crate::{
     app::{App, AppExit},
     event::Events,
     plugin::Plugin,
-    stage, startup_stage,
+    stage, startup_stage, PluginGroup, PluginGroupBuilder,
 };
 use bevy_ecs::{FromResources, IntoQuerySystem, Resources, System, World};
 
@@ -271,4 +271,23 @@ impl AppBuilder {
         plugin.build(self);
         self
     }
+
+    pub fn add_plugin_group<T: PluginGroup>(&mut self, mut group: T) -> &mut Self {
+        let mut plugin_group_builder = PluginGroupBuilder::default();
+        group.build(&mut plugin_group_builder);
+        plugin_group_builder.finish(self);
+        self
+    }
+
+    pub fn add_plugin_group_with<T, F>(&mut self, mut group: T, func: F) -> &mut Self
+    where
+        T: PluginGroup,
+        F: FnOnce(&mut PluginGroupBuilder) -> &mut PluginGroupBuilder,
+    {
+        let mut plugin_group_builder = PluginGroupBuilder::default();
+        group.build(&mut plugin_group_builder);
+        func(&mut plugin_group_builder);
+        plugin_group_builder.finish(self);
+        self
+    }
 }

crates/bevy_app/src/lib.rs

@@ -7,6 +7,7 @@ mod app;
 mod app_builder;
 mod event;
 mod plugin;
+mod plugin_group;
 mod schedule_runner;
 
 pub use app::*;
@@ -14,6 +15,7 @@ pub use app_builder::*;
 pub use bevy_derive::DynamicPlugin;
 pub use event::*;
 pub use plugin::*;
+pub use plugin_group::*;
 pub use schedule_runner::*;
 
 pub mod prelude {
@@ -21,7 +23,6 @@ pub mod prelude {
         app::App,
         app_builder::AppBuilder,
         event::{EventReader, Events},
-        plugin::Plugin,
+        stage, DynamicPlugin, Plugin, PluginGroup,
-        stage, DynamicPlugin,
     };
 }

crates/bevy_app/src/plugin_group.rs

@@ -0,0 +1,103 @@
+use crate::{AppBuilder, Plugin};
+use bevy_utils::HashMap;
+use std::any::TypeId;
+
+pub trait PluginGroup {
+    fn build(&mut self, group: &mut PluginGroupBuilder);
+}
+
+struct PluginEntry {
+    plugin: Box<dyn Plugin>,
+    enabled: bool,
+}
+
+#[derive(Default)]
+pub struct PluginGroupBuilder {
+    plugins: HashMap<TypeId, PluginEntry>,
+    order: Vec<TypeId>,
+}
+
+impl PluginGroupBuilder {
+    pub fn add<T: Plugin>(&mut self, plugin: T) -> &mut Self {
+        self.order.push(TypeId::of::<T>());
+        self.plugins.insert(
+            TypeId::of::<T>(),
+            PluginEntry {
+                plugin: Box::new(plugin),
+                enabled: true,
+            },
+        );
+        self
+    }
+
+    pub fn add_before<Target: Plugin, T: Plugin>(&mut self, plugin: T) -> &mut Self {
+        let target_index = self
+            .order
+            .iter()
+            .enumerate()
+            .find(|(_i, ty)| **ty == TypeId::of::<Target>())
+            .map(|(i, _)| i)
+            .unwrap_or_else(|| {
+                panic!("Plugin does not exist: {}", std::any::type_name::<Target>())
+            });
+        self.order.insert(target_index, TypeId::of::<T>());
+        self.plugins.insert(
+            TypeId::of::<T>(),
+            PluginEntry {
+                plugin: Box::new(plugin),
+                enabled: true,
+            },
+        );
+        self
+    }
+
+    pub fn add_after<Target: Plugin, T: Plugin>(&mut self, plugin: T) -> &mut Self {
+        let target_index = self
+            .order
+            .iter()
+            .enumerate()
+            .find(|(_i, ty)| **ty == TypeId::of::<Target>())
+            .map(|(i, _)| i)
+            .unwrap_or_else(|| {
+                panic!("Plugin does not exist: {}", std::any::type_name::<Target>())
+            });
+        self.order.insert(target_index + 1, TypeId::of::<T>());
+        self.plugins.insert(
+            TypeId::of::<T>(),
+            PluginEntry {
+                plugin: Box::new(plugin),
+                enabled: true,
+            },
+        );
+        self
+    }
+
+    pub fn enable<T: Plugin>(&mut self) -> &mut Self {
+        let mut plugin_entry = self
+            .plugins
+            .get_mut(&TypeId::of::<T>())
+            .expect("Cannot enable a plugin that does not exist");
+        plugin_entry.enabled = true;
+        self
+    }
+
+    pub fn disable<T: Plugin>(&mut self) -> &mut Self {
+        let mut plugin_entry = self
+            .plugins
+            .get_mut(&TypeId::of::<T>())
+            .expect("Cannot disable a plugin that does not exist");
+        plugin_entry.enabled = false;
+        self
+    }
+
+    pub fn finish(self, app: &mut AppBuilder) {
+        for ty in self.order.iter() {
+            if let Some(entry) = self.plugins.get(ty) {
+                if entry.enabled {
+                    log::debug!("added plugin: {}", entry.plugin.name());
+                    entry.plugin.build(app);
+                }
+            }
+        }
+    }
+}

examples/app/plugin_group.rs

@@ -0,0 +1,50 @@
+use bevy::{app::PluginGroupBuilder, prelude::*};
+
+/// PluginGroups are a way to group sets of plugins that should be registered together.
+fn main() {
+    App::build()
+        // The app.add_default_plugins() you see in all of the examples is just an alias for this:
+        .add_plugin_group(DefaultPlugins)
+        // Adding a plugin group adds all plugins in the group by default
+        .add_plugin_group(HelloWorldPlugins)
+        // You can also modify a PluginGroup (such as disabling plugins) like this:
+        // .add_plugin_group_with(HelloWorldPlugins, |group| {
+        //     group
+        //         .disable::<PrintWorldPlugin>()
+        //         .add_before::<PrintHelloPlugin, _>(bevy::diagnostic::PrintDiagnosticsPlugin::default())
+        // })
+        .run();
+}
+
+/// A group of plugins that produce the "hello world" behavior
+pub struct HelloWorldPlugins;
+
+impl PluginGroup for HelloWorldPlugins {
+    fn build(&mut self, group: &mut PluginGroupBuilder) {
+        group.add(PrintHelloPlugin).add(PrintWorldPlugin);
+    }
+}
+
+pub struct PrintHelloPlugin;
+
+impl Plugin for PrintHelloPlugin {
+    fn build(&self, app: &mut AppBuilder) {
+        app.add_system(print_hello_system.system());
+    }
+}
+
+fn print_hello_system() {
+    println!("hello");
+}
+
+pub struct PrintWorldPlugin;
+
+impl Plugin for PrintWorldPlugin {
+    fn build(&self, app: &mut AppBuilder) {
+        app.add_system(print_world_system.system());
+    }
+}
+
+fn print_world_system() {
+    println!("world");
+}

src/add_default_plugins.rs

@@ -1,50 +0,0 @@
-use crate::app::AppBuilder;
-
-pub trait AddDefaultPlugins {
-    fn add_default_plugins(&mut self) -> &mut Self;
-}
-
-impl AddDefaultPlugins for AppBuilder {
-    fn add_default_plugins(&mut self) -> &mut Self {
-        self.add_plugin(bevy_type_registry::TypeRegistryPlugin::default());
-        self.add_plugin(bevy_core::CorePlugin::default());
-        self.add_plugin(bevy_transform::TransformPlugin::default());
-        self.add_plugin(bevy_diagnostic::DiagnosticsPlugin::default());
-        self.add_plugin(bevy_input::InputPlugin::default());
-        self.add_plugin(bevy_window::WindowPlugin::default());
-        self.add_plugin(bevy_asset::AssetPlugin::default());
-        self.add_plugin(bevy_scene::ScenePlugin::default());
-
-        #[cfg(feature = "bevy_render")]
-        self.add_plugin(bevy_render::RenderPlugin::default());
-
-        #[cfg(feature = "bevy_sprite")]
-        self.add_plugin(bevy_sprite::SpritePlugin::default());
-
-        #[cfg(feature = "bevy_pbr")]
-        self.add_plugin(bevy_pbr::PbrPlugin::default());
-
-        #[cfg(feature = "bevy_ui")]
-        self.add_plugin(bevy_ui::UiPlugin::default());
-
-        #[cfg(feature = "bevy_text")]
-        self.add_plugin(bevy_text::TextPlugin::default());
-
-        #[cfg(feature = "bevy_audio")]
-        self.add_plugin(bevy_audio::AudioPlugin::default());
-
-        #[cfg(feature = "bevy_gilrs")]
-        self.add_plugin(bevy_gilrs::GilrsPlugin::default());
-
-        #[cfg(feature = "bevy_gltf")]
-        self.add_plugin(bevy_gltf::GltfPlugin::default());
-
-        #[cfg(feature = "bevy_winit")]
-        self.add_plugin(bevy_winit::WinitPlugin::default());
-
-        #[cfg(feature = "bevy_wgpu")]
-        self.add_plugin(bevy_wgpu::WgpuPlugin::default());
-
-        self
-    }
-}

src/default_plugins.rs

@@ -0,0 +1,58 @@
+use bevy_app::{PluginGroup, PluginGroupBuilder};
+
+use crate::app::AppBuilder;
+
+pub struct DefaultPlugins;
+
+impl PluginGroup for DefaultPlugins {
+    fn build(&mut self, group: &mut PluginGroupBuilder) {
+        group.add(bevy_type_registry::TypeRegistryPlugin::default());
+        group.add(bevy_core::CorePlugin::default());
+        group.add(bevy_transform::TransformPlugin::default());
+        group.add(bevy_diagnostic::DiagnosticsPlugin::default());
+        group.add(bevy_input::InputPlugin::default());
+        group.add(bevy_window::WindowPlugin::default());
+        group.add(bevy_asset::AssetPlugin::default());
+        group.add(bevy_scene::ScenePlugin::default());
+
+        #[cfg(feature = "bevy_render")]
+        group.add(bevy_render::RenderPlugin::default());
+
+        #[cfg(feature = "bevy_sprite")]
+        group.add(bevy_sprite::SpritePlugin::default());
+
+        #[cfg(feature = "bevy_pbr")]
+        group.add(bevy_pbr::PbrPlugin::default());
+
+        #[cfg(feature = "bevy_ui")]
+        group.add(bevy_ui::UiPlugin::default());
+
+        #[cfg(feature = "bevy_text")]
+        group.add(bevy_text::TextPlugin::default());
+
+        #[cfg(feature = "bevy_audio")]
+        group.add(bevy_audio::AudioPlugin::default());
+
+        #[cfg(feature = "bevy_gilrs")]
+        group.add(bevy_gilrs::GilrsPlugin::default());
+
+        #[cfg(feature = "bevy_gltf")]
+        group.add(bevy_gltf::GltfPlugin::default());
+
+        #[cfg(feature = "bevy_winit")]
+        group.add(bevy_winit::WinitPlugin::default());
+
+        #[cfg(feature = "bevy_wgpu")]
+        group.add(bevy_wgpu::WgpuPlugin::default());
+    }
+}
+
+pub trait AddDefaultPlugins {
+    fn add_default_plugins(&mut self) -> &mut Self;
+}
+
+impl AddDefaultPlugins for AppBuilder {
+    fn add_default_plugins(&mut self) -> &mut Self {
+        self.add_plugin_group(DefaultPlugins)
+    }
+}

src/lib.rs

@@ -37,10 +37,9 @@
     html_favicon_url = "https://bevyengine.org/assets/icon.png"
 )]
 
-mod add_default_plugins;
+mod default_plugins;
 pub mod prelude;
 
-pub use add_default_plugins::*;
 pub use bevy_app as app;
 pub use bevy_asset as asset;
 pub use bevy_core as core;
@@ -55,6 +54,7 @@ pub use bevy_transform as transform;
 pub use bevy_type_registry as type_registry;
 pub use bevy_utils as utils;
 pub use bevy_window as window;
+pub use default_plugins::*;
 
 #[cfg(feature = "bevy_audio")]
 pub use bevy_audio as audio;

src/prelude.rs

@@ -1,7 +1,7 @@
 pub use crate::{
     app::prelude::*, asset::prelude::*, core::prelude::*, ecs::prelude::*, input::prelude::*,
     math::prelude::*, property::prelude::*, scene::prelude::*, transform::prelude::*,
-    type_registry::RegisterType, window::prelude::*, AddDefaultPlugins,
+    type_registry::RegisterType, window::prelude::*, AddDefaultPlugins, DefaultPlugins,
 };
 
 #[cfg(feature = "bevy_audio")]