Add components interaction example (#951)

This add a small example of how to use agents in order to send
messages between components.

examples/Cargo.toml

@@ -23,4 +23,5 @@ members = [
   "timer",
   "todomvc",
   "two_apps",
+  "pub_sub",
 ]

examples/pub_sub/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "event_bus"
+version = "0.1.0"
+edition = "2018"
+
+[dependencies]
+log = "0.4"
+web_logger = "0.1"
+serde = { version = "1.0", features = ["derive"] }
+yew = { path = "../.." }
+stdweb = "0.4.20"

examples/pub_sub/README.md

@@ -0,0 +1,3 @@
+## Sender receiver example
+ Basic example that show how components that are not aware of each other can communicate
+ using an agent.

examples/pub_sub/src/event_bus.rs

@@ -0,0 +1,48 @@
+use serde::{Deserialize, Serialize};
+use std::collections::HashSet;
+use std::fmt::Debug;
+use yew::worker::*;
+
+#[derive(Serialize, Deserialize, Debug)]
+pub enum Request {
+    EventBusMsg(String),
+}
+
+pub struct EventBus {
+    link: AgentLink<EventBus>,
+    subscribers: HashSet<HandlerId>,
+}
+
+impl Agent for EventBus {
+    type Reach = Context;
+    type Message = ();
+    type Input = Request;
+    type Output = String;
+
+    fn create(link: AgentLink<Self>) -> Self {
+        EventBus {
+            link,
+            subscribers: HashSet::new(),
+        }
+    }
+
+    fn update(&mut self, _: Self::Message) {}
+
+    fn handle_input(&mut self, msg: Self::Input, _: HandlerId) {
+        match msg {
+            Request::EventBusMsg(s) => {
+                for sub in self.subscribers.iter() {
+                    self.link.respond(*sub, s.clone());
+                }
+            }
+        }
+    }
+
+    fn connected(&mut self, id: HandlerId) {
+        self.subscribers.insert(id);
+    }
+
+    fn disconnected(&mut self, id: HandlerId) {
+        self.subscribers.remove(&id);
+    }
+}

examples/pub_sub/src/lib.rs

@@ -0,0 +1,33 @@
+#![recursion_limit = "128"]
+
+mod event_bus;
+mod subscriber;
+mod producer;
+
+use subscriber::Subsciber;
+use producer::Producer;
+use yew::{html, Component, ComponentLink, Html, ShouldRender};
+
+pub struct Model {}
+
+impl Component for Model {
+    type Message = ();
+    type Properties = ();
+
+    fn create(_: Self::Properties, _: ComponentLink<Self>) -> Self {
+        Model {}
+    }
+
+    fn update(&mut self, _: Self::Message) -> ShouldRender {
+        false
+    }
+
+    fn view(&self) -> Html {
+        html! {
+            <div>
+                <Producer />
+                <Subsciber />
+            </div>
+        }
+    }
+}

examples/pub_sub/src/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    yew::start_app::<event_bus::Model>();
+}

examples/pub_sub/src/producer.rs

@@ -0,0 +1,46 @@
+use crate::event_bus::EventBus;
+use yew::agent::Dispatched;
+use yew::prelude::*;
+
+use crate::event_bus::Request;
+use yew::agent::Dispatcher;
+
+pub struct Producer {
+    link: ComponentLink<Producer>,
+    event_bus: Dispatcher<EventBus>,
+}
+
+pub enum Msg {
+    Clicked,
+}
+
+impl Component for Producer {
+    type Message = Msg;
+    type Properties = ();
+
+    fn create(_: Self::Properties, link: ComponentLink<Self>) -> Self {
+        let event_bus = EventBus::dispatcher();
+
+        Producer { event_bus, link }
+    }
+
+    fn update(&mut self, msg: Self::Message) -> ShouldRender {
+        match msg {
+            Msg::Clicked => {
+                self.event_bus
+                    .send(Request::EventBusMsg(format!("Message receieved")));
+                false
+            }
+        }
+    }
+
+    fn view(&self) -> Html {
+        html! {
+            <button
+                onclick=self.link.callback(|_| Msg::Clicked)
+            >
+                {"PUSH ME"}
+            </button>
+        }
+    }
+}

examples/pub_sub/src/subscriber.rs

@@ -0,0 +1,39 @@
+use super::event_bus::EventBus;
+use yew::agent::Bridged;
+use yew::{html, Bridge, Component, ComponentLink, Html, ShouldRender};
+
+pub enum Msg {
+    NewMessage(String),
+}
+
+pub struct Subsciber {
+    message: String,
+    _producer: Box<dyn Bridge<EventBus>>,
+}
+
+impl Component for Subsciber {
+    type Message = Msg;
+    type Properties = ();
+
+    fn create(_: Self::Properties, link: ComponentLink<Self>) -> Self {
+        let callback = link.callback(|s| Msg::NewMessage(s));
+        let _producer = EventBus::bridge(callback);
+        Subsciber {
+            message: format!("No message yet"),
+            _producer,
+        }
+    }
+
+    fn update(&mut self, msg: Self::Message) -> ShouldRender {
+        match msg {
+            Msg::NewMessage(s) => self.message = s,
+        }
+        true
+    }
+
+    fn view(&self) -> Html {
+        html! {
+            <h1>{self.message.clone()}</h1>
+        }
+    }
+}