[Merged by Bors] - Convenience method for entity naming

crates/bevy_core/src/lib.rs

@@ -15,7 +15,7 @@ pub mod prelude {
     //! The Bevy Core Prelude.
     #[doc(hidden)]
     pub use crate::{
-        FrameCountPlugin, Name, TaskPoolOptions, TaskPoolPlugin, TypeRegistrationPlugin,
+        DebugName, FrameCountPlugin, Name, TaskPoolOptions, TaskPoolPlugin, TypeRegistrationPlugin,
     };
 }
 

crates/bevy_core/src/name.rs

@@ -1,4 +1,6 @@
-use bevy_ecs::{component::Component, reflect::ReflectComponent};
+use bevy_ecs::{
+    component::Component, entity::Entity, query::WorldQuery, reflect::ReflectComponent,
+};
 use bevy_reflect::Reflect;
 use bevy_reflect::{std_traits::ReflectDefault, FromReflect};
 use bevy_utils::AHasher;
@@ -76,6 +78,40 @@ impl std::fmt::Display for Name {
     }
 }
 
+/// Convenient query for giving a human friendly name to an entity.
+///
+/// ```rust
+/// # use bevy_core::prelude::*;
+/// # use bevy_ecs::prelude::*;
+/// # #[derive(Component)] pub struct Score(f32);
+/// fn increment_score(mut scores: Query<(DebugName, &mut Score)>) {
+///     for (name, mut score) in &mut scores {
+///         score.0 += 1.0;
+///         if score.0.is_nan() {
+///             bevy_utils::tracing::error!("Score for {:?} is invalid", name);
+///         }
+///     }
+/// }
+/// # bevy_ecs::system::assert_is_system(increment_score);
+/// ```
+#[derive(WorldQuery)]
+pub struct DebugName {
+    /// A [`Name`] that the entity might have that is displayed if available.
+    pub name: Option<&'static Name>,
+    /// The unique identifier of the entity as a fallback.
+    pub entity: Entity,
+}
+
+impl<'a> std::fmt::Debug for DebugNameItem<'a> {
+    #[inline(always)]
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        match self.name {
+            Some(name) => write!(f, "{:?} ({:?})", &name, &self.entity),
+            None => std::fmt::Debug::fmt(&self.entity, f),
+        }
+    }
+}
+
 /* Conversions from strings */
 
 impl From<&str> for Name {