Struct Commands 

pub struct Commands<'w> { /* private fields */ }

System parameter that queues structural mutations for deferred application.

Commands buffers spawn, despawn, insert, and remove operations. These are applied between schedule stages via World::apply_commands, avoiding mid-iteration archetype changes.

fn spawn_units(mut cmds: Commands<'_>) {
    cmds.spawn((Position { x: 0.0, y: 0.0 },));
    cmds.despawn(old_entity);
    cmds.insert(entity, Health(100));
    cmds.remove::<Velocity>(entity);
}

Implementations

impl<'w> Commands<'w>

pub fn spawn<B: Bundle + Send + 'static>(&mut self, bundle: B)

Spawn an entity with the given component bundle (deferred).

pub fn despawn(&mut self, entity: Entity)

Despawn an entity (deferred).

pub fn insert<C: Component>(&mut self, entity: Entity, component: C)

Insert a component into an entity (deferred).

If the entity already has this component type, the value is overwritten.

pub fn remove<C: Component>(&mut self, entity: Entity)

Remove a component from an entity (deferred).

pub fn schedule_deadline<T: Send + 'static>( &mut self, deadline: Timestamp, event: T, )

Schedule a deadline event (deferred).

The event type must have been registered with World::add_deadline_type::<T>().

pub fn cancel_deadline<T: Send + 'static>(&mut self, id: DeadlineId)

Cancel a previously scheduled deadline (deferred).

pub fn len(&self) -> usize

Returns the number of queued commands.

pub fn is_empty(&self) -> bool

Returns true if no commands are queued.

Trait Implementations

impl SystemParam for Commands<'_>

type Item<'w> = Commands<'w>

The concrete type produced for a given world lifetime.

fn access() -> Vec<Access>

Declare what world data this parameter accesses.

unsafe fn fetch<'w>(world: UnsafeWorldCell) -> Commands<'w>

Extract the parameter from the world.