Struct moonshine_kind::InstanceCommands

pub struct InstanceCommands<'a, T: Kind>(/* private fields */);

EntityCommands with kind semantics.

Usage

On its own, this type is not very useful. Instead, it is designed to be extended using traits. This allows you to design commands for a specific kind of an entity in a type-safe manner.

Example

#[derive(Component)]
struct Apple;

#[derive(Component)]
struct Eat;

trait EatApple {
    fn eat(&mut self);
}

impl EatApple for InstanceCommands<'_, Apple> {
    fn eat(&mut self) {
        info!("Crunch!");
        self.despawn();
    }
}

fn eat_apples(apples: Query<Instance<Apple>, With<Eat>>, mut commands: Commands) {
    for apple in apples.iter() {
        commands.instance(apple).eat();
    }
}

Implementations

impl<'a, T: Kind> InstanceCommands<'a, T>

pub unsafe fn from_entity_unchecked(entity: EntityCommands<'a>) -> Self

Creates a new InstanceCommands<T> from EntityCommands without any validation.

Safety

Assumes entity is a valid instance of kind T.

pub fn instance(&self) -> Instance<T>

Returns the associated Instance<T>.

pub fn entity(&self) -> Entity

Returns the associated Entity.

pub fn as_entity(&mut self) -> &mut EntityCommands<'a>

Returns the associated EntityCommands.

Methods from Deref<Target = EntityCommands<'a>>

pub fn id(&self) -> Entity

Returns the Entity id of the entity.

Example

fn my_system(mut commands: Commands) {
    let entity_id = commands.spawn_empty().id();
}

pub fn reborrow(&mut self) -> EntityCommands<'_>

Returns an EntityCommands with a smaller lifetime. This is useful if you have &mut EntityCommands but you need EntityCommands.

pub fn insert(&mut self, bundle: impl Bundle) -> &mut EntityCommands<'_>

Adds a Bundle of components to the entity.

This will overwrite any previous value(s) of the same component type.

Panics

The command will panic when applied if the associated entity does not exist.

To avoid a panic in this case, use the command Self::try_insert instead.

Example

#[derive(Component)]
struct Health(u32);
#[derive(Component)]
struct Strength(u32);
#[derive(Component)]
struct Defense(u32);

#[derive(Bundle)]
struct CombatBundle {
    health: Health,
    strength: Strength,
}

fn add_combat_stats_system(mut commands: Commands, player: Res<PlayerEntity>) {
    commands
        .entity(player.entity)
        // You can insert individual components:
        .insert(Defense(10))
        // You can also insert pre-defined bundles of components:
        .insert(CombatBundle {
            health: Health(100),
            strength: Strength(40),
        })
        // You can also insert tuples of components and bundles.
        // This is equivalent to the calls above:
        .insert((
            Defense(10),
            CombatBundle {
                health: Health(100),
                strength: Strength(40),
            },
        ));
}

pub fn try_insert(&mut self, bundle: impl Bundle) -> &mut EntityCommands<'_>

Tries to add a Bundle of components to the entity.

This will overwrite any previous value(s) of the same component type.

Note

Unlike Self::insert, this will not panic if the associated entity does not exist.

Example

#[derive(Component)]
struct Health(u32);
#[derive(Component)]
struct Strength(u32);
#[derive(Component)]
struct Defense(u32);

#[derive(Bundle)]
struct CombatBundle {
    health: Health,
    strength: Strength,
}

fn add_combat_stats_system(mut commands: Commands, player: Res<PlayerEntity>) {
  commands.entity(player.entity)
   // You can try_insert individual components:
    .try_insert(Defense(10))
     
   // You can also insert tuples of components:
    .try_insert(CombatBundle {
        health: Health(100),
        strength: Strength(40),
    });
    
   // Suppose this occurs in a parallel adjacent system or process
   commands.entity(player.entity)
     .despawn();

   commands.entity(player.entity)
   // This will not panic nor will it add the component
     .try_insert(Defense(5));
}

pub fn remove<T>(&mut self) -> &mut EntityCommands<'_>

where T: Bundle,

Removes a Bundle of components from the entity.

Example

#[derive(Component)]
struct Health(u32);
#[derive(Component)]
struct Strength(u32);
#[derive(Component)]
struct Defense(u32);

#[derive(Bundle)]
struct CombatBundle {
    health: Health,
    strength: Strength,
}

fn remove_combat_stats_system(mut commands: Commands, player: Res<PlayerEntity>) {
    commands
        .entity(player.entity)
        // You can remove individual components:
        .remove::<Defense>()
        // You can also remove pre-defined Bundles of components:
        .remove::<CombatBundle>()
        // You can also remove tuples of components and bundles.
        // This is equivalent to the calls above:
        .remove::<(Defense, CombatBundle)>();
}

pub fn despawn(&mut self)

Despawns the entity.

See World::despawn for more details.

Note

This won’t clean up external references to the entity (such as parent-child relationships if you’re using bevy_hierarchy), which may leave the world in an invalid state.

Panics

The command will panic when applied if the associated entity does not exist.

Example

fn remove_character_system(
    mut commands: Commands,
    character_to_remove: Res<CharacterToRemove>
)
{
    commands.entity(character_to_remove.entity).despawn();
}

pub fn add<M>( &mut self, command: impl EntityCommand<M> ) -> &mut EntityCommands<'_>

where M: 'static,

Pushes an EntityCommand to the queue, which will get executed for the current Entity.

Examples

commands
    .spawn_empty()
    // Closures with this signature implement `EntityCommand`.
    .add(|entity: EntityWorldMut| {
        println!("Executed an EntityCommand for {:?}", entity.id());
    });

pub fn retain<T>(&mut self) -> &mut EntityCommands<'_>

where T: Bundle,

Removes all components except the given Bundle from the entity.

This can also be used to remove all the components from the entity by passing it an empty Bundle.

Example

#[derive(Component)]
struct Health(u32);
#[derive(Component)]
struct Strength(u32);
#[derive(Component)]
struct Defense(u32);

#[derive(Bundle)]
struct CombatBundle {
    health: Health,
    strength: Strength,
}

fn remove_combat_stats_system(mut commands: Commands, player: Res<PlayerEntity>) {
    commands
        .entity(player.entity)
        // You can retain a pre-defined Bundle of components,
        // with this removing only the Defense component
        .retain::<CombatBundle>()
        // You can also retain only a single component
        .retain::<Health>()
        // And you can remove all the components by passing in an empty Bundle
        .retain::<()>();
}

pub fn log_components(&mut self)

Logs the components of the entity at the info level.

Panics

The command will panic when applied if the associated entity does not exist.

pub fn commands(&mut self) -> Commands<'_, '_>

Returns the underlying Commands.

Trait Implementations

impl<'a, T: Kind> Deref for InstanceCommands<'a, T>

type Target = EntityCommands<'a>

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<'a, T: Kind> DerefMut for InstanceCommands<'a, T>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<'a, T: Kind> From<&InstanceCommands<'a, T>> for Instance<T>

fn from(commands: &InstanceCommands<'a, T>) -> Self

Converts to this type from the input type.

impl<'a, T: Kind> From<InstanceCommands<'a, T>> for Instance<T>

fn from(commands: InstanceCommands<'a, T>) -> Self

Converts to this type from the input type.