Enable Agents to send messages to themselves. (#1215)

* Agents can now send messages to themselves

* Agents callbacks now accept Into<Message>

* Clean old comment

* Remove AgentLink's send_message_batch

examples/npm_and_rest/src/gravatar.rs

@@ -38,7 +38,6 @@ impl GravatarService {
             if meta.status.is_success() {
                 callback.emit(data)
             } else {
-                // format_err! is a macro in crate `failure`
                 callback.emit(Err(anyhow!(
                     "{}: error getting profile https://gravatar.com/",
                     meta.status

yew/src/agent/link.rs

@@ -34,14 +34,23 @@ impl<AGN: Agent> AgentLink<AGN> {
         self.responder.respond(id, output);
     }
 
+    /// Send a message to the agent
+    pub fn send_message<T>(&self, msg: T)
+    where
+        T: Into<AGN::Message>,
+    {
+        self.scope.send(AgentLifecycleEvent::Message(msg.into()));
+    }
+
     /// Create a callback which will send a message to the agent when invoked.
-    pub fn callback<F, IN>(&self, function: F) -> Callback<IN>
+    pub fn callback<F, IN, M>(&self, function: F) -> Callback<IN>
     where
-        F: Fn(IN) -> AGN::Message + 'static,
+        M: Into<AGN::Message>,
+        F: Fn(IN) -> M + 'static,
     {
         let scope = self.scope.clone();
         let closure = move |input| {
-            let output = function(input);
+            let output = function(input).into();
             scope.send(AgentLifecycleEvent::Message(output));
         };
         closure.into()
@@ -87,6 +96,7 @@ impl<AGN: Agent> AgentScope<AGN> {
         let shared_agent = Rc::new(RefCell::new(AgentRunnable::new()));
         AgentScope { shared_agent }
     }
+
     /// Schedule message for sending to agent
     pub fn send(&self, update: AgentLifecycleEvent<AGN>) {
         let envelope = AgentEnvelope {
@@ -128,7 +138,7 @@ pub(crate) enum AgentLifecycleEvent<AGN: Agent> {
     Message(AGN::Message),
     /// Client connected
     Connected(HandlerId),
-    /// Received mesasge from Client
+    /// Received message from Client
     Input(AGN::Input, HandlerId),
     /// Client disconnected
     Disconnected(HandlerId),

yew/src/html/scope.rs

@@ -166,7 +166,10 @@ impl<COMP: Component> Scope<COMP> {
         self.update(ComponentUpdate::Message(msg.into()), false);
     }
 
-    /// Send a batch of messages to the component
+    /// Send a batch of messages to the component.
+    ///
+    /// This is useful for reducing re-renders of the components because the messages are handled
+    /// together and the view function is called only once if needed.
     pub fn send_message_batch(&self, messages: Vec<COMP::Message>) {
         self.update(ComponentUpdate::MessageBatch(messages), false);
     }