Struct ReadSignal

pub struct ReadSignal<T>(/* private fields */);

Receive changes from a signal.

Changes will stop being received when this is destroyed:

let x = Signal::new(1);
let seen_by_y = Rc::new(Cell::new(0));
let y = x.read().map({
    clone!(seen_by_y);
    move|&x| seen_by_y.set(x)
});
assert_eq!(seen_by_y.get(), 1);
x.write().set(2);
assert_eq!(seen_by_y.get(), 2);
mem::drop(y);
// We won't see this update
x.write().set(3);
assert_eq!(seen_by_y.get(), 2);

Implementations

impl<T: 'static> ReadSignal<T>

pub fn current(&self) -> Ref<'_, T>

The current value of the signal

pub fn only_changes(&self) -> ReadSignal<T>

where T: Clone + Eq,

Only propagate actual changes to the signal value.

let all_updates_count = Rc::new(Cell::new(0));
let only_changes_count = Rc::new(Cell::new(0));
let x = Signal::new(0);
let all_updates = x.read().map({
    clone!(all_updates_count);
    move |_| all_updates_count.set(all_updates_count.get() + 1)
});
let only_changes = x.read().only_changes().map({
    clone!(only_changes_count);
    move |_| only_changes_count.set(only_changes_count.get() + 1)
});

x.write().set(1);
x.write().set(1);
assert_eq!(all_updates_count.get(), 3, "One for init + 2 updates");
assert_eq!(only_changes_count.get(), 2, "One for init + 1 actual change");

pub fn map<Output, Generate>(&self, generate: Generate) -> ReadSignal<Output>

where Output: 'static, Generate: 'static + Fn(&T) -> Output,

Map a function onto the inner value to produce a new ReadSignal.

This only exists to make type inference easier, and just forwards its arguments to map_to.

pub fn map_to<Output>( &self, receiver: impl SignalReceiver<T, Output>, ) -> ReadSignal<Output>

where Output: 'static,

Receive changes to a signal.

Trait Implementations

impl<T> Clone for ReadSignal<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

const fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.