Struct Components

pub struct Components { /* private fields */ }

Stores metadata associated with each kind of Component in a given World.

Implementations

impl Components

pub fn init_component<T: Component>( &mut self, storages: &mut Storages, ) -> ComponentId

Initializes a component of type T with this instance. If a component of this type has already been initialized, this will return the ID of the pre-existing component.

See also

• Components::component_id()
• Components::init_component_with_descriptor()

pub fn init_component_with_descriptor( &mut self, storages: &mut Storages, descriptor: ComponentDescriptor, ) -> ComponentId

Initializes a component described by descriptor.

Note

If this method is called multiple times with identical descriptors, a distinct ComponentId will be created for each one.

See also

• Components::component_id()
• Components::init_component()

pub fn len(&self) -> usize

Returns the number of components registered with this instance.

pub fn is_empty(&self) -> bool

Returns true if there are no components registered with this instance. Otherwise, this returns false.

pub fn get_info(&self, id: ComponentId) -> Option<&ComponentInfo>

Gets the metadata associated with the given component.

This will return an incorrect result if id did not come from the same world as self. It may return None or a garbage value.

pub fn get_name(&self, id: ComponentId) -> Option<&str>

Returns the name associated with the given component.

This will return an incorrect result if id did not come from the same world as self. It may return None or a garbage value.

pub unsafe fn get_info_unchecked(&self, id: ComponentId) -> &ComponentInfo

Gets the metadata associated with the given component.

Safety

id must be a valid ComponentId

pub fn get_id(&self, type_id: TypeId) -> Option<ComponentId>

Type-erased equivalent of Components::component_id().

pub fn component_id<T: Component>(&self) -> Option<ComponentId>

Returns the ComponentId of the given Component type T.

The returned ComponentId is specific to the Components instance it was retrieved from and should not be used with another Components instance.

Returns None if the Component type has not yet been initialized using Components::init_component().

use bevy_ecs::prelude::*;

let mut world = World::new();

#[derive(Component)]
struct ComponentA;

let component_a_id = world.init_component::<ComponentA>();

assert_eq!(component_a_id, world.components().component_id::<ComponentA>().unwrap())

See also

• Components::get_id()
• Components::resource_id()
• World::component_id()

pub fn get_resource_id(&self, type_id: TypeId) -> Option<ComponentId>

Type-erased equivalent of Components::resource_id().

pub fn resource_id<T: Resource>(&self) -> Option<ComponentId>

Returns the ComponentId of the given Resource type T.

The returned ComponentId is specific to the Components instance it was retrieved from and should not be used with another Components instance.

Returns None if the Resource type has not yet been initialized using Components::init_resource().

use bevy_ecs::prelude::*;

let mut world = World::new();

#[derive(Resource, Default)]
struct ResourceA;

let resource_a_id = world.init_resource::<ResourceA>();

assert_eq!(resource_a_id, world.components().resource_id::<ResourceA>().unwrap())

See also

• Components::component_id()
• Components::get_resource_id()

pub fn init_resource<T: Resource>(&mut self) -> ComponentId

Initializes a Resource of type T with this instance. If a resource of this type has already been initialized, this will return the ID of the pre-existing resource.

See also

• Components::resource_id()

pub fn init_non_send<T: Any>(&mut self) -> ComponentId

Initializes a non-send resource of type T with this instance. If a resource of this type has already been initialized, this will return the ID of the pre-existing resource.

pub fn iter(&self) -> impl Iterator<Item = &ComponentInfo> + '_

Gets an iterator over all components registered with this instance.

Trait Implementations

impl Debug for Components

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Components

fn default() -> Components

Returns the “default value” for a type.

impl<'a> SystemParam for &'a Components

type State = ()

Used to store data which persists across invocations of a system.

type Item<'w, 's> = &'w Components

The item type returned when constructing this system param. The value of this associated type should be Self, instantiated with new lifetimes.

fn init_state(_world: &mut World, _system_meta: &mut SystemMeta) -> Self::State

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

unsafe fn get_param<'w, 's>( _state: &'s mut Self::State, _system_meta: &SystemMeta, world: UnsafeWorldCell<'w>, _change_tick: Tick, ) -> Self::Item<'w, 's>

Creates a parameter to be passed into a SystemParamFunction.

unsafe fn new_archetype( state: &mut Self::State, archetype: &Archetype, system_meta: &mut SystemMeta, )

For the specified Archetype, registers the components accessed by this SystemParam (if applicable).a

fn apply(state: &mut Self::State, system_meta: &SystemMeta, world: &mut World)

Applies any deferred mutations stored in this SystemParam’s state. This is used to apply Commands during apply_deferred.

fn queue( state: &mut Self::State, system_meta: &SystemMeta, world: DeferredWorld<'_>, )

Queues any deferred mutations to be applied at the next apply_deferred.

impl<'a> ReadOnlySystemParam for &'a Components