[Merged by Bors] - Add Query::contains #3090
There are no files selected for viewing
| Original file line number | Diff line number | Diff line change |
|---|---|---|
|
|
@@ -975,6 +975,44 @@ where | |
| self.state | ||
| .is_empty(self.world, self.last_change_tick, self.change_tick) | ||
| } | ||
|
|
||
| /// Returns `true` if the given [`Entity`] matches the query. | ||
| /// | ||
| /// # Example | ||
| /// | ||
| /// ``` | ||
| /// # use bevy_ecs::prelude::*; | ||
| /// # | ||
| /// # #[derive(Component)] | ||
| /// # struct Player; | ||
| /// # #[derive(Component)] | ||
| /// # struct Alive; | ||
| /// fn check_if_alive( | ||
| /// player_query: Query<Entity, With<Player>>, | ||
| /// alive_query: Query<(), With<Alive>>, | ||
| /// ) { | ||
| /// if let Ok(player) = player_query.get_single() { | ||
|
There was a problem hiding this comment. Hmm, so I think a more idiomatic version of this would use #3088 (or the option workaroud detailed therein). I think this method is more useful for pseudo-relations, e.g. 'has this pet's owning player been killed', or 'how many neighbours of this entity are alive'. However, I'm struggling to think of a super succinct version which does this. There was a problem hiding this comment. Also, replacing the get_single with There was a problem hiding this comment. Here's an alternate example to steal that's a bit more idiomatic. #[derive(Component)]
struct InRange;
struct Target {
entity: Entity,
}
fn targeting_system(in_range_query: Query<&InRange>, target: Res<Target>) {
if in_range_query.contains(target.entity) {
println!("Bam!")
}
} |
||
| /// if alive_query.contains(player) { | ||
| /// println!("The player is alive."); | ||
| /// } else { | ||
| /// println!("The player is dead!"); | ||
| /// } | ||
| /// } | ||
| /// } | ||
| /// # check_if_alive.system(); | ||
| /// ``` | ||
| #[inline] | ||
| pub fn contains(&self, entity: Entity) -> bool { | ||
| unsafe { | ||
| self.state.get_unchecked_manual( | ||
|
There was a problem hiding this comment. At the moment, this unsafe block is identical to the one in Please just replace the body with I think that a more optimised version is possible, but it would be challenging to review due to the amount of unsafety required. |
||
| self.world, | ||
| entity, | ||
| self.last_change_tick, | ||
| self.change_tick, | ||
| ) | ||
| } | ||
| .is_ok() | ||
| } | ||
| } | ||
|
|
||
| /// An error that occurs when retrieving a specific [`Entity`]'s component from a [`Query`] | ||
|
|
||
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
I don't propose that you take any action on this comment, just noting down my thoughts.
By a strict reading of these docs, a valid implementation of this function would be
{true}; we don't specify the behaviour if the condition is false. It is however intended to be read asif and only if.However, this fits the pattern of documentation in
std, e.g.Vec::contains. I tried to find a rust-lang/rust issue on these doc items, but failed to do so.