use_bridge hook for agents (#2125)

* Add Redirect Comp.

* Fix router behaviour.

* Fix output.

* Fix pr-flow.

* Remove Redirect.

* Readd 77b46bf.

* Add use_bridge hook.

* Add documentation.

packages/yew-agent/src/hooks.rs

@@ -0,0 +1,56 @@
+use std::cell::RefCell;
+use std::rc::Rc;
+
+use crate::*;
+use yew::prelude::*;
+
+/// State handle for [`use_bridge`] hook
+pub struct UseBridgeHandle<T>
+where
+    T: Bridged,
+{
+    inner: Rc<RefCell<Box<dyn Bridge<T>>>>,
+}
+
+impl<T> UseBridgeHandle<T>
+where
+    T: Bridged,
+{
+    /// Send a message to an agent.
+    pub fn send(&self, msg: T::Input) {
+        let mut bridge = self.inner.borrow_mut();
+        bridge.send(msg);
+    }
+}
+
+/// A hook to bridge to an Agent.
+///
+/// This hooks will only bridge the agent once over the entire component lifecycle.
+///
+/// Takes a callback as the only argument. The callback will be updated on every render to make
+/// sure captured values (if any) are up to date.
+pub fn use_bridge<T, F>(on_output: F) -> UseBridgeHandle<T>
+where
+    T: Bridged,
+    F: Fn(T::Output) + 'static,
+{
+    let on_output = Rc::new(on_output);
+
+    let on_output_clone = on_output.clone();
+    let on_output_ref = use_ref(move || on_output_clone);
+
+    // Refresh the callback on every render.
+    {
+        let mut on_output_ref = on_output_ref.borrow_mut();
+        *on_output_ref = on_output;
+    }
+
+    let bridge = use_ref(move || {
+        T::bridge(Callback::from(move |output| {
+            let on_output = on_output_ref.borrow().clone();
+            on_output(output);
+        }))
+    });
+
+    UseBridgeHandle { inner: bridge }
+}

packages/yew-agent/src/lib.rs

@@ -1,11 +1,13 @@
 //! This module contains types to support multi-threading and state management.
 
+mod hooks;
 mod link;
 mod local;
 mod pool;
 pub mod utils;
 mod worker;
 
+pub use hooks::{use_bridge, UseBridgeHandle};
 pub use link::AgentLink;
 pub(crate) use link::*;
 pub use local::{Context, Job};

website/docs/concepts/agents.md

@@ -43,6 +43,8 @@ In order for agents to run concurrently, Yew uses
 
 A bridge allows bi-directional communication between an agent and a component. Bridges also allow agents to communicate with one another.
 
+A `use_bridge` hook is also provided to create bridges in a function component.
+
 ### Dispatchers
 
 A dispatcher allows uni-directional communication between a component and an agent. A dispatcher allows a component to send messages to an agent.