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Deprecate type aliases for WorldQuery::Fetch (#8843)

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# Objective

`WorldQuery::Fetch` is a type used to optimize the implementation of
queries. These types are hidden and not intended to be outside of the
engine, so there is no need to provide type aliases to make it easier to
refer to them. If a user absolutely needs to refer to one of these
types, they can always just refer to the associated type directly.

## Solution

Deprecate these type aliases.

---

## Changelog

- Deprecated the type aliases `QueryFetch` and `ROQueryFetch`.

## Migration Guide

The type aliases `bevy_ecs::query::QueryFetch` and `ROQueryFetch` have
been deprecated. If you need to refer to a `WorldQuery` struct's fetch
type, refer to the associated type defined on `WorldQuery` directly:

```rust
// Before:
type MyFetch<'w> = QueryFetch<'w, MyQuery>;
type MyFetchReadOnly<'w> = ROQueryFetch<'w, MyQuery>;

// After:
type MyFetch<'w> = <MyQuery as WorldQuery>::Fetch;
type MyFetchReadOnly<'w> = <<MyQuery as WorldQuery>::ReadOnly as WorldQuery>::Fetch;
```
This commit is contained in:
JoJoJet 2023-06-19 18:46:08 -04:00 committed by GitHub
parent 8b5bf42c28
commit f63656051a
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1 changed files with 7 additions and 4 deletions
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11
crates/bevy_ecs/src/query/fetch.rs
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@ -455,15 +455,18 @@ pub unsafe trait WorldQuery {
/// This must only be implemented for read-only [`WorldQuery`]'s.
pub unsafe trait ReadOnlyWorldQuery: WorldQuery<ReadOnly = Self> {}
/// The `Fetch` of a [`WorldQuery`], which is used to store state for each archetype/table.
pub type QueryFetch<'w, Q> = <Q as WorldQuery>::Fetch<'w>;
/// The item type returned when a [`WorldQuery`] is iterated over
pub type QueryItem<'w, Q> = <Q as WorldQuery>::Item<'w>;
/// The read-only `Fetch` of a [`WorldQuery`], which is used to store state for each archetype/table.
pub type ROQueryFetch<'w, Q> = QueryFetch<'w, <Q as WorldQuery>::ReadOnly>;
/// The read-only variant of the item type returned when a [`WorldQuery`] is iterated over immutably
pub type ROQueryItem<'w, Q> = QueryItem<'w, <Q as WorldQuery>::ReadOnly>;
/// The `Fetch` of a [`WorldQuery`], which is used to store state for each archetype/table.
#[deprecated = "use <Q as WorldQuery>::Fetch<'w> instead"]
pub type QueryFetch<'w, Q> = <Q as WorldQuery>::Fetch<'w>;
/// The read-only `Fetch` of a [`WorldQuery`], which is used to store state for each archetype/table.
#[deprecated = "use <<Q as WorldQuery>::ReadOnly as WorldQuery>::Fetch<'w> instead"]
pub type ROQueryFetch<'w, Q> = <<Q as WorldQuery>::ReadOnly as WorldQuery>::Fetch<'w>;
/// SAFETY: no component or archetype access
unsafe impl WorldQuery for Entity {
type Fetch<'w> = ();