Macro impl_message_handler

macro_rules! impl_message_handler {
    ($actor_type:ty, [$($msg_type:ty),* $(,)?]) => { ... };
}

Implements the MessageHandler trait for a given actor type.

This macro simplifies the process of handling multiple message types within an actor. It generates the necessary boilerplate code to downcast a Box<dyn Any + Send> message to its concrete type and then calls the appropriate Message::handle implementation on the actor.

Usage

struct MyActor;

impl Actor for MyActor { /* ... */ }

struct Msg1;
struct Msg2;

impl Message<Msg1> for MyActor {
    type Reply = ();
    async fn handle(&mut self, msg: Msg1) -> Self::Reply { /* ... */ }
}

impl Message<Msg2> for MyActor {
    type Reply = String;
    async fn handle(&mut self, msg: Msg2) -> Self::Reply { /* ... */ "response".to_string() }
}

// This will implement `MessageHandler` for `MyActor`, allowing it to handle `Msg1` and `Msg2`.
impl_message_handler!(MyActor, [Msg1, Msg2]);

Arguments

• $actor_type: The type of the actor for which to implement MessageHandler.
• [$($msg_type:ty),+]: A list of message types that the actor can handle.

Internals

This macro facilitates dynamic message dispatch by downcasting Box<dyn std::any::Any + Send> message payloads to their concrete types at runtime.