default() shorthand (bevyengine#4071)

Adds a `default()` shorthand for `Default::default()` ... because life is too short to constantly type `Default::default()`.

```rust
use bevy::prelude::*;

#[derive(Default)]
struct Foo {
  bar: usize,
  baz: usize,
}

// Normally you would do this:
let foo = Foo {
  bar: 10,
  ..Default::default()
};

// But now you can do this:
let foo = Foo {
  bar: 10,
  ..default()
};
```

The examples have been adapted to use `..default()`. I've left internal crates as-is for now because they don't pull in the bevy prelude, and the ergonomics of each case should be considered individually.

Author: cart

crates/bevy_internal/src/prelude.rs

@@ -2,7 +2,7 @@
 pub use crate::{
     app::prelude::*, asset::prelude::*, core::prelude::*, ecs::prelude::*, input::prelude::*,
     log::prelude::*, math::prelude::*, reflect::prelude::*, scene::prelude::*,
-    transform::prelude::*, window::prelude::*, DefaultPlugins, MinimalPlugins,
+    transform::prelude::*, utils::prelude::*, window::prelude::*, DefaultPlugins, MinimalPlugins,
 };
 
 pub use bevy_derive::bevy_main;

crates/bevy_utils/src/default.rs

@@ -0,0 +1,30 @@
+/// An ergonomic abbreviation for [`Default::default()`] to make initializing structs easier.
+/// This is especially helpful when combined with ["struct update syntax"](https://doc.rust-lang.org/book/ch05-01-defining-structs.html#creating-instances-from-other-instances-with-struct-update-syntax).
+/// ```
+/// use bevy_utils::default;
+///
+/// #[derive(Default)]
+/// struct Foo {
+///   a: usize,
+///   b: usize,
+///   c: usize,
+/// }
+///
+/// // Normally you would initialize a struct with defaults using "struct update syntax"
+/// // combined with `Default::default()`. This example sets `Foo::bar` to 10 and the remaining
+/// // values to their defaults.
+/// let foo = Foo {
+///   a: 10,
+///   ..Default::default()
+/// };
+///
+/// // But now you can do this, which is equivalent:
+/// let foo = Foo {
+///   a: 10,
+///   ..default()
+/// };
+/// ```
+#[inline]
+pub fn default<T: Default>() -> T {
+    std::default::Default::default()
+}

crates/bevy_utils/src/lib.rs

@@ -1,16 +1,22 @@
-mod enum_variant_meta;
+pub mod prelude {
+    pub use crate::default;
+}
+
 pub mod label;
 
+mod default;
+mod enum_variant_meta;
+
 pub use ahash::AHasher;
+pub use default::default;
 pub use enum_variant_meta::*;
-pub type Entry<'a, K, V> = hashbrown::hash_map::Entry<'a, K, V, RandomState>;
 pub use hashbrown;
-use hashbrown::hash_map::RawEntryMut;
 pub use instant::{Duration, Instant};
 pub use tracing;
 pub use uuid::Uuid;
 
 use ahash::RandomState;
+use hashbrown::hash_map::RawEntryMut;
 use std::{
     fmt::Debug,
     future::Future,
@@ -26,6 +32,8 @@ pub type BoxedFuture<'a, T> = Pin<Box<dyn Future<Output = T> + Send + 'a>>;
 #[cfg(target_arch = "wasm32")]
 pub type BoxedFuture<'a, T> = Pin<Box<dyn Future<Output = T> + 'a>>;
 
+pub type Entry<'a, K, V> = hashbrown::hash_map::Entry<'a, K, V, RandomState>;
+
 /// A hasher builder that will create a fixed hasher.
 #[derive(Debug, Clone, Default)]
 pub struct FixedState;

examples/2d/contributors.rs

@@ -100,11 +100,11 @@ fn setup_contributor_selection(mut commands: Commands, asset_server: Res<AssetSe
                     custom_size: Some(Vec2::new(1.0, 1.0) * SPRITE_SIZE),
                     color: Color::hsla(hue, SATURATION_DESELECTED, LIGHTNESS_DESELECTED, ALPHA),
                     flip_x: flipped,
-                    ..Default::default()
+                    ..default()
                 },
                 texture: texture_handle.clone(),
                 transform,
-                ..Default::default()
+                ..default()
             })
             .id();
 
@@ -126,7 +126,7 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
         .insert_bundle(TextBundle {
             style: Style {
                 align_self: AlignSelf::FlexEnd,
-                ..Default::default()
+                ..default()
             },
             text: Text {
                 sections: vec![
@@ -147,9 +147,9 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
                         },
                     },
                 ],
-                ..Default::default()
+                ..default()
             },
-            ..Default::default()
+            ..default()
         });
 }
 

examples/2d/many_sprites.rs

@@ -57,9 +57,9 @@ fn setup(mut commands: Commands, assets: Res<AssetServer>) {
                 },
                 sprite: Sprite {
                     custom_size: Some(tile_size),
-                    ..Default::default()
+                    ..default()
                 },
-                ..Default::default()
+                ..default()
             });
         }
     }

examples/2d/mesh2d.rs

@@ -17,6 +17,6 @@ fn setup(
         mesh: meshes.add(Mesh::from(shape::Quad::default())).into(),
         transform: Transform::default().with_scale(Vec3::splat(128.)),
         material: materials.add(ColorMaterial::from(Color::PURPLE)),
-        ..Default::default()
+        ..default()
     });
 }

examples/2d/move_sprite.rs

@@ -20,7 +20,7 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
         .spawn_bundle(SpriteBundle {
             texture: asset_server.load("branding/icon.png"),
             transform: Transform::from_xyz(100., 0., 0.),
-            ..Default::default()
+            ..default()
         })
         .insert(Direction::Up);
 }

examples/2d/rect.rs

@@ -13,8 +13,8 @@ fn setup(mut commands: Commands) {
         sprite: Sprite {
             color: Color::rgb(0.25, 0.25, 0.75),
             custom_size: Some(Vec2::new(50.0, 50.0)),
-            ..Default::default()
+            ..default()
         },
-        ..Default::default()
+        ..default()
     });
 }

examples/2d/rotation.rs

@@ -66,7 +66,7 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
     commands
         .spawn_bundle(SpriteBundle {
             texture: ship_handle,
-            ..Default::default()
+            ..default()
         })
         .insert(Player {
             movement_speed: 500.0,                  // metres per second
@@ -78,14 +78,14 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
         .spawn_bundle(SpriteBundle {
             texture: enemy_a_handle.clone(),
             transform: Transform::from_xyz(0.0 - horizontal_margin, 0.0, 0.0),
-            ..Default::default()
+            ..default()
         })
         .insert(SnapToPlayer);
     commands
         .spawn_bundle(SpriteBundle {
             texture: enemy_a_handle,
             transform: Transform::from_xyz(0.0, 0.0 - vertical_margin, 0.0),
-            ..Default::default()
+            ..default()
         })
         .insert(SnapToPlayer);
 
@@ -94,7 +94,7 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
         .spawn_bundle(SpriteBundle {
             texture: enemy_b_handle.clone(),
             transform: Transform::from_xyz(0.0 + horizontal_margin, 0.0, 0.0),
-            ..Default::default()
+            ..default()
         })
         .insert(RotateToPlayer {
             rotation_speed: f32::to_radians(45.0), // degrees per second
@@ -103,7 +103,7 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
         .spawn_bundle(SpriteBundle {
             texture: enemy_b_handle,
             transform: Transform::from_xyz(0.0, 0.0 + vertical_margin, 0.0),
-            ..Default::default()
+            ..default()
         })
         .insert(RotateToPlayer {
             rotation_speed: f32::to_radians(90.0), // degrees per second

examples/2d/sprite.rs

@@ -11,6 +11,6 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
     commands.spawn_bundle(OrthographicCameraBundle::new_2d());
     commands.spawn_bundle(SpriteBundle {
         texture: asset_server.load("branding/icon.png"),
-        ..Default::default()
+        ..default()
     });
 }

examples/2d/sprite_flipping.rs

@@ -16,8 +16,8 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
             flip_x: true,
             // And don't flip it upside-down ( the default )
             flip_y: false,
-            ..Default::default()
+            ..default()
         },
-        ..Default::default()
+        ..default()
     });
 }

examples/2d/sprite_sheet.rs

@@ -42,7 +42,7 @@ fn setup(
         .spawn_bundle(SpriteSheetBundle {
             texture_atlas: texture_atlas_handle,
             transform: Transform::from_scale(Vec3::splat(6.0)),
-            ..Default::default()
+            ..default()
         })
         .insert(AnimationTimer(Timer::from_seconds(0.1, true)));
 }

examples/2d/text2d.rs

@@ -34,21 +34,21 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
     commands
         .spawn_bundle(Text2dBundle {
             text: Text::with_section("translation", text_style.clone(), text_alignment),
-            ..Default::default()
+            ..default()
         })
         .insert(AnimateTranslation);
     // Demonstrate changing rotation
     commands
         .spawn_bundle(Text2dBundle {
             text: Text::with_section("rotation", text_style.clone(), text_alignment),
-            ..Default::default()
+            ..default()
         })
         .insert(AnimateRotation);
     // Demonstrate changing scale
     commands
         .spawn_bundle(Text2dBundle {
             text: Text::with_section("scale", text_style, text_alignment),
-            ..Default::default()
+            ..default()
         })
         .insert(AnimateScale);
 }

examples/2d/texture_atlas.rs

@@ -66,16 +66,16 @@ fn setup(
         transform: Transform {
             translation: Vec3::new(150.0, 0.0, 0.0),
             scale: Vec3::splat(4.0),
-            ..Default::default()
+            ..default()
         },
         sprite: TextureAtlasSprite::new(vendor_index),
         texture_atlas: atlas_handle,
-        ..Default::default()
+        ..default()
     });
     // draw the atlas itself
     commands.spawn_bundle(SpriteBundle {
         texture: texture_atlas_texture,
         transform: Transform::from_xyz(-300.0, 0.0, 0.0),
-        ..Default::default()
+        ..default()
     });
 }

examples/3d/3d_scene.rs

@@ -18,28 +18,28 @@ fn setup(
     commands.spawn_bundle(PbrBundle {
         mesh: meshes.add(Mesh::from(shape::Plane { size: 5.0 })),
         material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
-        ..Default::default()
+        ..default()
     });
     // cube
     commands.spawn_bundle(PbrBundle {
         mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
         material: materials.add(Color::rgb(0.8, 0.7, 0.6).into()),
         transform: Transform::from_xyz(0.0, 0.5, 0.0),
-        ..Default::default()
+        ..default()
     });
     // light
     commands.spawn_bundle(PointLightBundle {
         point_light: PointLight {
             intensity: 1500.0,
             shadows_enabled: true,
-            ..Default::default()
+            ..default()
         },
         transform: Transform::from_xyz(4.0, 8.0, 4.0),
-        ..Default::default()
+        ..default()
     });
     // camera
     commands.spawn_bundle(PerspectiveCameraBundle {
         transform: Transform::from_xyz(-2.0, 2.5, 5.0).looking_at(Vec3::ZERO, Vec3::Y),
-        ..Default::default()
+        ..default()
     });
 }