1#![cfg_attr(target_family = "wasm", no_main)]
 2
 3use gpui::{App, Context, Entity, EventEmitter, prelude::*};
 4use gpui_platform::application;
 5
 6struct Counter {
 7    count: usize,
 8}
 9
10struct Change {
11    increment: usize,
12}
13
14impl EventEmitter<Change> for Counter {}
15
16fn run_example() {
17    application().run(|cx: &mut App| {
18        let counter: Entity<Counter> = cx.new(|_cx| Counter { count: 0 });
19        let subscriber = cx.new(|cx: &mut Context<Counter>| {
20            cx.subscribe(&counter, |subscriber, _emitter, event, _cx| {
21                subscriber.count += event.increment * 2;
22            })
23            .detach();
24
25            Counter {
26                count: counter.read(cx).count * 2,
27            }
28        });
29
30        counter.update(cx, |counter, cx| {
31            counter.count += 2;
32            cx.notify();
33            cx.emit(Change { increment: 2 });
34        });
35
36        assert_eq!(subscriber.read(cx).count, 4);
37    });
38}
39
40#[cfg(not(target_family = "wasm"))]
41fn main() {
42    run_example();
43}
44
45#[cfg(target_family = "wasm")]
46#[wasm_bindgen::prelude::wasm_bindgen(start)]
47pub fn start() {
48    gpui_platform::web_init();
49    run_example();
50}