A library for efficient local message-passing (pretty much actors but without the concurrent part).

Add this to the [dependencies] of your Cargo.toml:

[dependencies]
send = { git = "https://github.com/Synaptic-Simulations/send", branch = "main" }

send requires nightly, and you have to add this to the top of your crate:

#![feature(min_specialization)]
#![feature(negative_impls)]

send is a pretty small library because it has just one thing to do: safe, type-safe message passing.

Everything in send is an Actor. Actors can receive messages, send messages, and contain sub-actors. Pretty simple.

To make something an actor, you simply:

use send::Actor;

#[derive(Actor)]
pub struct MyActor {}

What this does is register all sub-actors of this actor to be used for broadcasted messages.

Messages can be any type, without any special traits needing to be implemented.

The Framework is the 'root' of all Actors. It allows you to send external messages to all actors, a specific one, or a specific one and all its children.

Creating a Framework is done with Framework::new() and the root actor:

let framework: Framework<MyActor> = Framework::new(MyActor {});

To receive messages on an actor, simply implement the trait send::Receiver for your actor:

impl<T> Receiver<Message, T> for MyActor {
    fn receive(&mut self, message: &Message, context: Context<Self, T>) {
        // Do something with `message`
    }
}

Over here, Message is the type that you send, and MyActor is the type of the root actor.

This implements Receiver for all possible root actors.

Obviously this boilerplate is annoying, so enter macros!

Use the send::receive macro to implement Receiver for your actor:

use send::receive;

struct MyActor;

receive! {
    Message => MyActor = |&mut self, message, context| {
        // Your code here
    }
}

It even supports generics (but they're a bit clunky because macros can't really capture generics):

use send::receive;

struct MyMessage<const N: u8>;

recieve! {
    %(const N: u8) MyMessage<N> => MyActor = |&mut self, message, context| {
        // Your code here
    }
}

In receive , context allows you to send messages to all actors, a specific one, or a specific one and its sub-actors. These messages are sent and evaluated immediately.

Every method on Context requires you to pass self as the first parameter, for safety.