Struct QueryParamBuilder

pub struct QueryParamBuilder<T>(/* private fields */);

A SystemParamBuilder for a Query. This takes a closure accepting an &mut QueryBuilder and uses the builder to construct the query’s state. This can be used to add additional filters, or to configure the components available to FilteredEntityRef or FilteredEntityMut.

Example

let system = (QueryParamBuilder::new(|builder| {
    builder.with::<Player>();
}),)
    .build_state(&mut world)
    .build_system(|query: Query<()>| {
        for _ in &query {
            // This only includes entities with an `Player` component.
        }
    });

// When collecting multiple builders into a `Vec`,
// use `new_box()` to erase the closure type.
let system = (vec![
    QueryParamBuilder::new_box(|builder| {
        builder.with::<Player>();
    }),
    QueryParamBuilder::new_box(|builder| {
        builder.without::<Player>();
    }),
],)
    .build_state(&mut world)
    .build_system(|query: Vec<Query<()>>| {});

Implementations

impl<T> QueryParamBuilder<T>

pub fn new<D: QueryData, F: QueryFilter>(f: T) -> Self

where T: FnOnce(&mut QueryBuilder<'_, D, F>),

Creates a SystemParamBuilder for a Query that accepts a callback to configure the QueryBuilder.

impl<'a, D: QueryData, F: QueryFilter> QueryParamBuilder<Box<dyn FnOnce(&mut QueryBuilder<'_, D, F>) + 'a>>

pub fn new_box(f: impl FnOnce(&mut QueryBuilder<'_, D, F>) + 'a) -> Self

Creates a SystemParamBuilder for a Query that accepts a callback to configure the QueryBuilder. This boxes the callback so that it has a common type and can be put in a Vec.

Trait Implementations

impl<'w, 's, D: QueryData + 'static, F: QueryFilter + 'static, T: FnOnce(&mut QueryBuilder<'_, D, F>)> SystemParamBuilder<Query<'w, 's, D, F>> for QueryParamBuilder<T>

fn build( self, world: &mut World, system_meta: &mut SystemMeta, ) -> QueryState<D, F>

Registers any World access used by this SystemParam and creates a new instance of this param’s State.

fn build_state(self, world: &mut World) -> SystemState<P>

Create a SystemState from a SystemParamBuilder. To create a system, call SystemState::build_system on the result.