3 unstable releases
0.2.1 | Jan 17, 2023 |
---|---|
0.2.0 | Jan 16, 2023 |
0.1.0 | Jan 13, 2023 |
#92 in #callback
251 downloads per month
Used in yewprint
22KB
283 lines
yew-callbacks
Yet another crate nobody asked for.
This crate provides a derive macro Callbacks
that can be used on Yew enum messages to help
managing callbacks.
But why
Callbacks in Yew's components are easy to create but hard to manage. To avoid duplication you
should create them preemptively in the create()
method of your component, store them in the
state of your component, then pass clones to the children. Unfortunately this creates a lot of
bloat.
To address this, yew-callbacks
provides a macro that will automatically create some kind of
cache for your callbacks. You create this cache once in the create()
method of your component
and then you can use the methods to get your callbacks easily.
Example
use yew::prelude::*;
use yew_callbacks::Callbacks;
#[derive(Debug, Callbacks)]
enum Msg {
OnClick(MouseEvent),
}
#[derive(Debug)]
struct App {
cb: MsgCallbacks<Self>,
}
impl Component for App {
type Message = Msg;
type Properties = ();
fn create(ctx: &Context<Self>) -> Self {
Self {
cb: ctx.link().into(),
}
}
fn view(&self, ctx: &Context<Self>) -> Html {
html! {
<button onclick={self.cb.on_click()}>
{ "Hello World!" }
</button>
}
}
}
Why care
Not perf.
Your children components will be updated if their properties changed. If you do
onclick={ctx.link().callback(Msg::OnClick)
then the child component will think there is an
update every time the parent component updates. This is because doing
ctx.link().callback(Msg::OnClick)
creates a new callback every time.
Handling multiple child components
This crate also allows currying the arguments of your callback.
Example
use yew::prelude::*;
use yew_callbacks::Callbacks;
#[derive(Debug, Callbacks)]
enum Msg {
OnClick(#[curry] usize, MouseEvent),
}
#[derive(Debug)]
struct App {
games: Vec<AttrValue>,
cb: MsgCallbacks<Self>,
}
impl Component for App {
type Message = Msg;
type Properties = ();
fn create(ctx: &Context<Self>) -> Self {
Self {
games: vec![
"Freedom Planet 2".into(),
"Asterigos: Curse of the Stars".into(),
"Fran Bow".into(),
"Cats in Time".into(),
"Ittle Dew 2+".into(),
"Inscryption".into(),
],
cb: ctx.link().into(),
}
}
fn view(&self, _ctx: &Context<Self>) -> Html {
self
.games
.iter()
.enumerate()
.map(|(i, game)| html! {
<button onclick={self.cb.on_click(i)}>
{ format!("You should try {game}") }
</button>
})
.collect()
}
}
Dependencies
~0–385KB