Contexts

Contexts contains the state of your Stores. You rarely (if ever) need to manage them manually, but it's useful to understand how they work.

You can easily create a new local context with Context::new. Then just pass it into a dispatch and you have your very own locally managed store!

#![allow(unused)]
fn main() {
extern crate yew;
extern crate yewdux;
use yew::prelude::*;
use yewdux::prelude::*;

#[derive(Clone, PartialEq, Default, Store)]
struct Counter(u32);

let cx = yewdux::Context::new();
let dispatch = Dispatch::<Counter>::new(&cx);
}

Changes to one context are not reflected in any others:

#![allow(unused)]
fn main() {
extern crate yewdux;
use yewdux::prelude::*;
#[derive(Clone, PartialEq, Default, Store)]
struct Counter(u32);
let cx_1 = yewdux::Context::new();
let dispatch_1 = Dispatch::<Counter>::new(&cx_1);

let cx_2 = yewdux::Context::new();
let dispatch_2 = Dispatch::<Counter>::new(&cx_2);

dispatch_1.set(Counter(1));
dispatch_2.set(Counter(2));

assert!(dispatch_1.get() != dispatch_2.get());
}

The Global Context

You may already be familar with the global context. This is what you are using when you create a dispatch with Dispatch::global. The global context is thread-local, meaning you can access it from anywhere in your code as long as it's on the same thread (for wasm this is effectively everywhere).

#![allow(unused)]
fn main() {
extern crate yewdux;
use yewdux::prelude::*;
#[derive(Clone, PartialEq, Default, Store)]
struct Counter(u32);
// These are equivalent!
let dispatch_1 = Dispatch::<Counter>::global();
let dispatch_2 = Dispatch::<Counter>::new(&yewdux::Context::global());

dispatch_1.set(Counter(1));

assert!(dispatch_1.get() == dispatch_2.get());
}

IMPORTANT: Use of global context is only supported for wasm targets. See ssr support for more details.