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Refactor event system documentation in system_param.rs (#17364)

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Just clarify the role of `ParamSet` in this code snippet
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Younes 2025-01-14 20:38:25 +01:00 committed by GitHub
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12
crates/bevy_ecs/src/system/system_param.rs
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@ -645,12 +645,16 @@ unsafe impl<'w, 's, D: ReadOnlyQueryData + 'static, F: QueryFilter + 'static> Re
/// # }
/// fn event_system(
/// mut set: ParamSet<(
/// // `EventReader`s and `EventWriter`s conflict with each other,
/// // since they both access the event queue resource for `MyEvent`.
/// // PROBLEM: `EventReader` and `EventWriter` cannot be used together normally,
/// // because they both need access to the same event queue.
/// // SOLUTION: `ParamSet` allows these conflicting parameters to be used safely
/// // by ensuring only one is accessed at a time.
/// EventReader<MyEvent>,
/// EventWriter<MyEvent>,
/// // `&World` reads the entire world, so a `ParamSet` is the only way
/// // that it can be used in the same system as any mutable accesses.
/// // PROBLEM: `&World` needs read access to everything, which conflicts with
/// // any mutable access in the same system.
/// // SOLUTION: `ParamSet` ensures `&World` is only accessed when we're not
/// // using the other mutable parameters.
/// &World,
/// )>,
/// ) {