add event_bus_typed

event_bus/src/handler.rs

@@ -0,0 +1,47 @@
+use std::future::Future;
+
+/// Handler trait for asynchronous event callbacks.
+///
+/// This trait is automatically implemented for any closure matching
+/// `Fn(E) -> Future<Output = ()> + Send + Sync + 'static`.
+///
+/// By using `Fn(E) -> <Self as AsyncHandler<E>>::Fut` as a supertrait,
+/// Rust propagates the event type `E` directly into the closure's parameter,
+/// enabling seamless turbofish syntax with clean field access:
+///
+/// ```rust,no_run
+/// # use event_bus::EventBus;
+/// # #[derive(Clone)] struct MessageUpdatedEvent { id: u64 }
+/// # let bus = EventBus::new();
+/// bus.on_async::<MessageUpdatedEvent>(|event| async move {
+///     println!("Updated: {:?}", event.id);
+/// });
+/// ```
+pub trait AsyncHandler<E>: Fn(E) -> <Self as AsyncHandler<E>>::Fut + Send + Sync + 'static {
+    type Fut: Future<Output = ()> + Send + 'static;
+}
+
+impl<E, F, Fut> AsyncHandler<E> for F
+where
+    F: Fn(E) -> Fut + Send + Sync + 'static,
+    Fut: Future<Output = ()> + Send + 'static,
+{
+    type Fut = Fut;
+}
+
+/// Handler trait for asynchronous event callbacks with an injected context.
+///
+/// Automatically implemented for closures matching
+/// `Fn(C, E) -> Future<Output = ()> + Send + Sync + 'static`.
+pub trait AsyncHandlerWith<E, C>: Fn(C, E) -> <Self as AsyncHandlerWith<E, C>>::Fut + Send + Sync + 'static {
+    type Fut: Future<Output = ()> + Send + 'static;
+}
+
+impl<E, C, F, Fut> AsyncHandlerWith<E, C> for F
+where
+    C: Clone + Send + Sync + 'static,
+    F: Fn(C, E) -> Fut + Send + Sync + 'static,
+    Fut: Future<Output = ()> + Send + 'static,
+{
+    type Fut = Fut;
+}