Struct Scope

pub struct Scope<'a> { /* private fields */ }

A scope can be thought of as a “sum” of all modifications done by the compose function of the Compose trait. It holds the state of the composable and its children scopes. It is the “actual” node in the tree-structure of the composables.

Implementations

impl Scope<'_>

pub fn use_state<T>(&mut self, initial_value: T) -> State<T>

where T: Any + Send + Sync,

Creates a new state. States are persisted between each recomposition of the composable. Each time a state changes, the scope it belongs to is scheduled for recomposition.

pub fn use_state_with_id<T>( &mut self, state_id: TypedStateId<T>, initial_value: T, ) -> State<T>

where T: Any + Send + Sync,

Creates a new state with a given id. It is useful for cases where you want to reference a state in an external system or a different composable.

pub fn set_state<T>(&mut self, state: impl GetStateId<T>, value: T)

where T: Send + Sync + 'static,

Sets the value of the given state. The change happens immediately.

pub fn set_state_unchanged<T>(&mut self, state: impl GetStateId<T>, value: T)

where T: Send + Sync + 'static,

Sets the value of the given state without triggering a recomposition. The change happens immediately.

pub fn effect(&mut self, effect: impl Fn(), dependecies: impl Dependency)

A callback that is run only if the dependencies have changed.

pub fn use_mount(&mut self, callback: impl Fn())

Runs a callback when the component is first composed.

pub fn run_system<M>(&mut self, system: impl IntoSystem<(), (), M>)

Runs a system. The system is not cached and is “rebuilt” every time the composable recomposes. It is therefore not the most efficient way to to interact with the ECS world.

pub fn use_system_once<M>(&mut self, system: impl IntoSystem<(), (), M>)

Runs a system when the composable is first composed.

Trait Implementations

impl Debug for Scope<'_>

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

Formats the value using the given formatter.

impl Display for Scope<'_>

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

Formats the value using the given formatter.