#[forward]">

#[forward]

The #[hyperactor::forward] macro connects a user-defined handler trait implementation (like ShoppingListHandler) to the core Handler<T> trait required by the runtime.

In short, it generates the boilerplate needed to route incoming messages of type T to your high-level trait implementation.

What it generates

The macro expands to:

#[async_trait]
impl Handler<ShoppingList> for ShoppingListActor {
    async fn handle(&mut self, ctx: &Context<Self>, message: ShoppingList) -> Result<(), Error> {
        <Self as ShoppingListHandler>::handle(self, ctx, message).await
    }
}

This avoids having to manually match on enum variants or duplicate message logic.

When to use it

Use #[forward(MessageType)] when:

• You’ve defined a custom trait (e.g., ShoppingListHandler)

• You’re handling a message enum (like ShoppingList)

• You want the runtime to route messages to your trait automatically.

This is most often used alongside #[derive(Handler)], which generates the corresponding handler and client traits for a user-defined message enum.