Struct leptos::signal_prelude::Selector

pub struct Selector<T>where
    T: PartialEq + Eq + Clone + Hash + 'static,{ /* private fields */ }

A conditional signal that only notifies subscribers when a change in the source signal’s value changes whether the given function is true.

Implementations

impl<T> Selector<T>where T: PartialEq + Eq + Clone + Hash + 'static,

pub fn new(source: impl Fn() -> T + Clone + 'static) -> Selector<T>

Creates a conditional signal that only notifies subscribers when a change in the source signal’s value changes whether it is equal to the key value (as determined by PartialEq.)

You probably don’t need this, but it can be a very useful optimization in certain situations (e.g., “set the class selected if selected() == this_row_index) because it reduces them from O(n) to O(1).

let a = RwSignal::new(0);
let is_selected = Selector::new(move || a.get());
let total_notifications = Rc::new(RefCell::new(0));
let not = Rc::clone(&total_notifications);
create_isomorphic_effect({
    let is_selected = is_selected.clone();
    move |_| {
        if is_selected.selected(5) {
            *not.borrow_mut() += 1;
        }
    }
});

assert_eq!(is_selected.selected(5), false);
assert_eq!(*total_notifications.borrow(), 0);
a.set(5);
assert_eq!(is_selected.selected(5), true);
assert_eq!(*total_notifications.borrow(), 1);
a.set(5);
assert_eq!(is_selected.selected(5), true);
assert_eq!(*total_notifications.borrow(), 1);
a.set(4);
assert_eq!(is_selected.selected(5), false);

pub fn selected(&self, key: T) -> bool

Reactively checks whether the given key is selected.

pub fn remove(&self, key: &T)

Removes the listener for the given key.

Trait Implementations

impl<T> Clone for Selector<T>where T: Clone + PartialEq + Eq + Hash + 'static,

fn clone(&self) -> Selector<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Debug for Selector<T>where T: PartialEq + Eq + Clone + Hash + 'static,

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

Formats the value using the given formatter.