Function freya::prelude::use_set_compare

pub fn use_set_compare<R>(f: impl FnMut() -> R + 'static) -> SetCompare<R>
where
    R: Eq + Hash,

Creates a new SetCompare which efficiently tracks when a value changes to check if it is equal to a set of values.

Generally, you shouldn’t need to use this hook. Instead you can use [crate::use_memo]. If you have many values that you need to compare to a single value, this hook will change updates from O(n) to O(1) where n is the number of values you are comparing to.

use dioxus::prelude::*;

fn App() -> Element {
    let mut count = use_signal(|| 0);
    let compare = use_set_compare(move || count());

    rsx! {
        for i in 0..10 {
            // Child will only re-render when i == count
            Child { compare, i }
        }
        button {
            // This will only rerender the child with the old and new value of i == count
            // Because we are using a set compare, this will be O(1) instead of the O(n) performance of a selector
            onclick: move |_| count += 1,
            "Increment"
        }
    }
}

#[component]
fn Child(i: usize, compare: SetCompare<usize>) -> Element {
    let active = use_set_compare_equal(i, compare);
    if active() {
        rsx! { "Active" }
    } else {
        rsx! { "Inactive" }
    }
}