Struct Schedule 

pub struct Schedule { /* private fields */ }

A collection of systems, and the metadata and executor needed to run them in a certain order under certain conditions.

Schedule labels

Each schedule has a ScheduleLabel value. This value is used to uniquely identify the schedule when added to a World’s Schedules, and may be used to specify which schedule a system should be added to.

Example

Here is an example of a Schedule running a “Hello world” system:

fn hello_world() { println!("Hello world!") }

fn main() {
    let mut world = World::new();
    let mut schedule = Schedule::default();
    schedule.add_systems(hello_world);

    schedule.run(&mut world);
}

A schedule can also run several systems in an ordered way:

fn system_one() { println!("System 1 works!") }
fn system_two() { println!("System 2 works!") }
fn system_three() { println!("System 3 works!") }

fn main() {
    let mut world = World::new();
    let mut schedule = Schedule::default();
    schedule.add_systems((
        system_two,
        system_one.before(system_two),
        system_three.after(system_two),
    ));

    schedule.run(&mut world);
}

Schedules are often inserted into a World and identified by their ScheduleLabel only:

use bevy_ecs::schedule::ScheduleLabel;

// Declare a new schedule label.
#[derive(ScheduleLabel, Clone, Debug, PartialEq, Eq, Hash, Default)]
struct Update;

// This system shall be part of the schedule.
fn an_update_system() {
    println!("Hello world!");
}

fn main() {
    let mut world = World::new();

    // Add a system to the schedule with that label (creating it automatically).
    world.get_resource_or_init::<Schedules>().add_systems(Update, an_update_system);

    // Run the schedule, and therefore run the system.
    world.run_schedule(Update);
}

Implementations

impl Schedule

pub fn new(label: impl ScheduleLabel) -> Schedule

Constructs an empty Schedule.

pub fn is_changed(&self) -> bool

Returns whether this schedule has been changed since the last time it was built.

pub fn label(&self) -> Interned<dyn ScheduleLabel>

Returns the InternedScheduleLabel for this Schedule, corresponding to the ScheduleLabel this schedule was created with.

pub fn add_systems<M>( &mut self, systems: impl IntoScheduleConfigs<Box<dyn System<Out = (), In = ()>>, M>, ) -> &mut Schedule

Add a collection of systems to the schedule.

pub fn remove_systems_in_set<M>( &mut self, set: impl IntoSystemSet<M>, world: &mut World, policy: ScheduleCleanupPolicy, ) -> Result<usize, ScheduleError>

Removes all systems in a SystemSet. This will cause the schedule to be rebuilt when the schedule is run again. A ScheduleError is returned if the schedule needs to be Schedule::initialize’d or the set is not found.

Note that this can remove all systems of a type if you pass the system to this function as systems implicitly create a set based on the system type.

Example

let mut schedule = Schedule::default();
// add the system to the schedule
schedule.add_systems(my_system);
let mut world = World::default();

// remove the system
schedule.remove_systems_in_set(my_system, &mut world, ScheduleCleanupPolicy::RemoveSystemsOnly);

pub fn ignore_ambiguity<M1, M2, S1, S2>( &mut self, a: S1, b: S2, ) -> &mut Schedule

where S1: IntoSystemSet<M1>, S2: IntoSystemSet<M2>,

Suppress warnings and errors that would result from systems in these sets having ambiguities (conflicting access but indeterminate order) with systems in set.

pub fn configure_sets<M>( &mut self, sets: impl IntoScheduleConfigs<Interned<dyn SystemSet>, M>, ) -> &mut Schedule

Configures a collection of system sets in this schedule, adding them if they does not exist.

pub fn add_build_pass<T>(&mut self, pass: T) -> &mut Schedule

where T: ScheduleBuildPass,

Add a custom build pass to the schedule.

pub fn remove_build_pass<T>(&mut self)

where T: ScheduleBuildPass,

Remove a custom build pass.

pub fn set_build_settings( &mut self, settings: ScheduleBuildSettings, ) -> &mut Schedule

Changes miscellaneous build settings.

If settings.auto_insert_apply_deferred is false, this clears *_ignore_deferred edge settings configured so far.

Generally this method should be used before adding systems or set configurations to the schedule, not after.

pub fn get_build_settings(&self) -> ScheduleBuildSettings

Returns the schedule’s current ScheduleBuildSettings.

pub fn set_executor( &mut self, executor: impl SystemExecutor + 'static, ) -> &mut Schedule

Replaces the schedule’s executor.

pub fn set_apply_final_deferred( &mut self, apply_final_deferred: bool, ) -> &mut Schedule

Set whether the schedule applies deferred system buffers on final time or not. This is a catch-all in case a system uses commands but was not explicitly ordered before an instance of ApplyDeferred. By default this setting is true, but may be disabled if needed.

pub fn run(&mut self, world: &mut World)

Runs all systems in this schedule on the world, using its current execution strategy.

pub fn initialize( &mut self, world: &mut World, ) -> Result<Option<ScheduleBuildMetadata>, ScheduleBuildError>

Initializes any newly-added systems and conditions, rebuilds the executable schedule, and re-initializes the executor.

Moves all systems and run conditions out of the ScheduleGraph. If the schedule is built successfully, returns Some with the metadata. If the schedule has previously been built successfully, returns None.

pub fn graph(&self) -> &ScheduleGraph

Returns the ScheduleGraph.

pub fn graph_mut(&mut self) -> &mut ScheduleGraph

Returns a mutable reference to the ScheduleGraph.

pub fn check_change_ticks(&mut self, check: CheckChangeTicks)

Iterates the change ticks of all systems in the schedule and clamps any older than MAX_CHANGE_AGE. This prevents overflow and thus prevents false positives.

pub fn apply_deferred(&mut self, world: &mut World)

Directly applies any accumulated Deferred system parameters (like Commands) to the world.

Like always, deferred system parameters are applied in the “topological sort order” of the schedule graph. As a result, buffers from one system are only guaranteed to be applied before those of other systems if there is an explicit system ordering between the two systems.

This is used in rendering to extract data from the main world, storing the data in system buffers, before applying their buffers in a different world.

pub fn systems( &self, ) -> Result<impl Iterator<Item = (SystemKey, &Box<dyn System<Out = (), In = ()>>)>, ScheduleNotInitialized>

Returns an iterator over all systems in this schedule.

Note: this method will return ScheduleNotInitialized if the schedule has never been initialized or run.

pub fn systems_len(&self) -> usize

Returns the number of systems in this schedule.

Trait Implementations

impl Default for Schedule

fn default() -> Schedule

Creates a schedule with a default label. Only use in situations where you don’t care about the ScheduleLabel. Inserting a default schedule into the world risks overwriting another schedule. For most situations you should use Schedule::new.