Add more FromWorld implementations (#3945)

# Objective

Make `FromWorld` more useful for abstractions with a form similar to
```rs
trait FancyAbstraction {
  type PreInitializedData: FromWorld;
}
```

## Solution

Add a `FromWorld` implementation for `SystemState` as well as a way to group together multiple `FromWorld` implementing types as one.

Note: I plan to follow up this PR with another to add `Local` support to exclusive systems, which should get a fair amount of use from the `FromWorld` implementation on `SystemState`.
This commit is contained in:
TheRawMeatball 2022-04-05 20:04:34 +00:00
parent ea6e6f7db2
commit 73edb11db6
2 changed files with 17 additions and 0 deletions

View file

@ -2,6 +2,7 @@ use crate::{
archetype::{Archetype, ArchetypeComponentId, ArchetypeGeneration, ArchetypeId},
component::ComponentId,
entity::Entity,
prelude::FromWorld,
query::{
Access, Fetch, FetchState, FilterFetch, FilteredAccess, NopFetch, QueryCombinationIter,
QueryIter, WorldQuery,
@ -32,6 +33,15 @@ where
pub(crate) filter_state: F::State,
}
impl<Q: WorldQuery, F: WorldQuery> FromWorld for QueryState<Q, F>
where
F::Fetch: FilterFetch,
{
fn from_world(world: &mut World) -> Self {
world.query_filtered()
}
}
impl<Q: WorldQuery, F: WorldQuery> QueryState<Q, F>
where
F::Fetch: FilterFetch,

View file

@ -1,6 +1,7 @@
use crate::{
archetype::{Archetype, ArchetypeComponentId, ArchetypeGeneration, ArchetypeId},
component::ComponentId,
prelude::FromWorld,
query::{Access, FilteredAccessSet},
schedule::SystemLabel,
system::{
@ -229,6 +230,12 @@ impl<Param: SystemParam> SystemState<Param> {
}
}
impl<Param: SystemParam> FromWorld for SystemState<Param> {
fn from_world(world: &mut World) -> Self {
Self::new(world)
}
}
/// Conversion trait to turn something into a [`System`].
///
/// Use this to get a system from a function. Also note that every system implements this trait as