Struct Command 

#[non_exhaustive]
pub struct Command { /* private fields */ }

Side-effect command returned from Component::update.

A Command represents work that should happen outside the synchronous update call (HTTP/IO/timers), typically executed by the runtime and eventually producing more messages.

Implementations

impl Command

pub fn new(action: impl FnOnce() + 'static) -> Self

Run a one-shot action on the UI thread.

pub fn spawn<Msg, F>(f: F) -> Self

where Msg: Send + 'static, F: FnOnce(CommandLink<Msg>) + Send + 'static,

Spawn a background task that can send messages back.

pub fn after<Msg, F>(delay: Duration, f: F) -> Self

where Msg: Send + 'static, F: FnOnce(CommandLink<Msg>) + Send + 'static,

Run a background task after delay, without holding a worker while it waits.

Use this for debounces, retries, and recurring ticks instead of Command::spawn with a thread::sleep inside. The executor runs on a fixed pool of 2-8 workers, so a sleeping task occupies one for the whole delay: two recurring timers can park every worker on a low-core machine and stall unrelated background work behind them. A shared timer thread does the waiting here, and the task reaches the pool only once it is due.

Command::after(Duration::from_secs(1), |link: CommandLink<Msg>| {
    link.send(Msg::Tick);
})

Re-arming from the handler gives a recurring tick that costs no thread between firings. On the web target without the web feature there is no timer source, and the task runs immediately rather than being dropped.

pub fn spawn_keyed<Msg, F>( key: impl Into<Arc<str>>, policy: TaskPolicy, f: F, ) -> Self

where Msg: Send + 'static, F: FnOnce(CommandLink<Msg>) + Send + 'static,

Spawn a keyed background task with explicit coalescing policy.

Trait Implementations

impl Debug for Command

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

Formats the value using the given formatter.