Trait Event

pub trait Event: Component {
    type Traversal: Traversal;

    const AUTO_PROPAGATE: bool = false;
}

Something that “happens” and might be read / observed by app logic.

Events can be stored in an Events<E> resource You can conveniently access events using the EventReader and EventWriter system parameter.

Events can also be “triggered” on a World, which will then cause any Observer of that trigger to run.

This trait can be derived.

Events implement the Component type (and they automatically do when they are derived). Events are (generally) not directly inserted as components. More often, the ComponentId is used to identify the event type within the context of the ECS.

Events must be thread-safe.

Provided Associated Constants

const AUTO_PROPAGATE: bool = false

When true, this event will always attempt to propagate when triggered, without requiring a call to Trigger::propagate.

Required Associated Types

type Traversal: Traversal

The component that describes which Entity to propagate this event to next, when propagation is enabled.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl Event for RemovedComponentEntity

where Self: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for OnAdd

where Self: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for OnInsert

where Self: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for OnRemove

where Self: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for OnReplace

where Self: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()