dioxus/packages/signals/README.md
Leonard c866ae602b
Add system for creating component attributes + new #[component] attribute (#1448)
* Add `#[component]` attribute + system for creating component attributes + other stuff

* Delete inlineprops.rs

* Update inline_props.rs

* Cargo fmt

* Fix clippy warnings and paths in props/mods.rs

* Include where clause in `#[inline_props]` output

* Allow Clippy type complexity in `LinkProps`

* Allow the type complexity lint for the entire link.rs file

* Remove snake_case -> PascalCase converter, but rather enforce PascalCase

Also:
- Put the second function inside the main one instead of besides it.
- Simplify

* Simplify type check lints so they don't return false positives

They will not always work, but they won't return any false positives, like for aliases. This is likely going to be replaced by a more polished Clippy-backed linting system.

* Fix #583

* Cargo fmt

* Add docs for `deserialize()` and remove useless comment

* Add `#[component]` to prelude

* Merge branch 'master' of https://github.com/tigerros/dioxus

* #[inline_props] is no more. Except in the docs folder, but that's going to be removed

* Remove docs folder

* Remove docs from workspace

* Resolve `DeserializerOutput` conversation
2023-09-15 09:13:36 -05:00

2.9 KiB

Dioxus Signals

Dioxus Signals is an ergonomic Copy runtime for data with local subscriptions.

Copy Data

All signals implement Copy, even if the inner value does not implement copy. This makes it easy to move any data into futures or children.

use dioxus::prelude::*;
use dioxus_signals::*;

#[component]
fn App(cx: Scope) -> Element {
    let signal = use_signal(cx, || "hello world".to_string());

    spawn(async move {
        // signal is Copy even though String is not copy
        print!("{signal}");
    });

    render! {
        "{signal}"
    }
}

Local Subscriptions

Signals will only subscribe to components when you read from the signal in that component. It will never subscribe to a component when reading data in a future or event handler.

use dioxus::prelude::*;
use dioxus_signals::*;

#[component]
fn App(cx: Scope) -> Element {
    // Because signal is never read in this component, this component will not rerun when the signal changes
    let signal = use_signal(cx, || 0);

    render! {
        button {
            onclick: move |_| {
                *signal.write() += 1;
            },
            "Increase"
        }
        for id in 0..10 {
            Child {
                signal: signal,
            }
        }
    }
}

#[derive(Props, Clone, PartialEq)]
struct ChildProps {
    signal: Signal<usize>,
}

#[component]
fn Child(cx: Scope<ChildProps>) -> Element {
    // This component does read from the signal, so when the signal changes it will rerun
    render! {
        "{cx.props.signal}"
    }
}

Because subscriptions happen when you read from (not create) the data, you can provide signals through the normal context API:

use dioxus::prelude::*;
use dioxus_signals::*;

#[component]
fn App(cx: Scope) -> Element {
    // Because signal is never read in this component, this component will not rerun when the signal changes
    use_context_provider(cx, || Signal::new(0));
    
    render! {
        Child {}
    }
}

#[component]
fn Child(cx: Scope) -> Element {
    let signal: Signal<i32> = *use_context(cx).unwrap();
    // This component does read from the signal, so when the signal changes it will rerun
    render! {
        "{signal}"
    }
}

Computed Data

In addition to local subscriptions in components, dioxus-signals provides a way to derive data with local subscriptions.

The use_selector hook will only rerun when any signals inside the hook change:

use dioxus::prelude::*;
use dioxus_signals::*;

#[component]
fn App(cx: Scope) -> Element {
    let signal = use_signal(cx, || 0);
    let doubled = use_selector(cx, || signal * 2);

    render! {
        button {
            onclick: move |_| *signal.write() += 1,
            "Increase"
        }
        Child {
            signal: signal
        }
    }
}

#[component]
fn Child(cx: Scope, signal: ReadOnlySignal<usize>) -> Element {
    render! {
        "{signal}"
    }
}