Add Result handling to Commands and EntityCommands

benches/benches/bevy_ecs/world/commands.rs

@@ -2,8 +2,9 @@ use core::hint::black_box;
 
 use bevy_ecs::{
     component::Component,
-    system::Commands,
-    world::{Command, CommandQueue, World},
+    result::Result,
+    system::{Command, Commands},
+    world::{CommandQueue, World},
 };
 use criterion::Criterion;
 
@@ -136,16 +137,18 @@ struct FakeCommandA;
 struct FakeCommandB(u64);
 
 impl Command for FakeCommandA {
-    fn apply(self, world: &mut World) {
+    fn apply(self, world: &mut World) -> Result {
         black_box(self);
         black_box(world);
+        Ok(())
     }
 }
 
 impl Command for FakeCommandB {
-    fn apply(self, world: &mut World) {
+    fn apply(self, world: &mut World) -> Result {
         black_box(self);
         black_box(world);
+        Ok(())
     }
 }
 
@@ -180,9 +183,10 @@ pub fn fake_commands(criterion: &mut Criterion) {
 struct SizedCommand<T: Default + Send + Sync + 'static>(T);
 
 impl<T: Default + Send + Sync + 'static> Command for SizedCommand<T> {
-    fn apply(self, world: &mut World) {
+    fn apply(self, world: &mut World) -> Result {
         black_box(self);
         black_box(world);
+        Ok(())
     }
 }
 

crates/bevy_ecs/src/bundle.rs

@@ -336,12 +336,12 @@ impl SparseSetIndex for BundleId {
     }
 }
 
-// What to do on insertion if component already exists
+/// What to do on insertion if a component already exists.
 #[derive(Clone, Copy, Eq, PartialEq)]
-pub(crate) enum InsertMode {
+pub enum InsertMode {
     /// Any existing components of a matching type will be overwritten.
     Replace,
-    /// Any existing components of a matching type will kept unchanged.
+    /// Any existing components of a matching type will be left unchanged.
     Keep,
 }
 

crates/bevy_ecs/src/lib.rs

@@ -73,13 +73,13 @@ pub mod prelude {
             IntoSystemSet, IntoSystemSetConfigs, Schedule, Schedules, SystemSet,
         },
         system::{
-            Commands, Deferred, EntityCommand, EntityCommands, In, InMut, InRef, IntoSystem, Local,
-            NonSend, NonSendMut, ParamSet, Populated, Query, ReadOnlySystem, Res, ResMut, Resource,
-            Single, System, SystemIn, SystemInput, SystemParamBuilder, SystemParamFunction,
-            WithParamWarnPolicy,
+            Command, Commands, Deferred, EntityCommand, EntityCommands, In, InMut, InRef,
+            IntoSystem, Local, NonSend, NonSendMut, ParamSet, Populated, Query, ReadOnlySystem,
+            Res, ResMut, Resource, Single, System, SystemIn, SystemInput, SystemParamBuilder,
+            SystemParamFunction, WithParamWarnPolicy,
         },
         world::{
-            Command, EntityMut, EntityRef, EntityWorldMut, FilteredResources, FilteredResourcesMut,
+            EntityMut, EntityRef, EntityWorldMut, FilteredResources, FilteredResourcesMut,
             FromWorld, OnAdd, OnInsert, OnRemove, OnReplace, World,
         },
     };