Macro stakker::query

macro_rules! query {
    ([$actor:expr, $stakker:expr], $method:ident( $($x:expr),* $(,)? )) => { ... };
}

Synchronously query an actor for information

This requires a &mut Stakker and is intended for interfacing the actor system to external code. It makes a synchronous call to an actor method, and the actor method may return data from its own state. However if the actor is not yet in the Ready state, or has terminated, then None will be returned. No attempt is made to handle the call asynchronously, e.g. to queue it. So this is only intended to aid in interfacing the actor system to non-actor code.

// Where `s` is a `&mut Stakker`
match query!([actor, s], method(args...)) {
    None => ...,          // Actor not in ready state
    Some(result) => ...,  // Successful call
}

Implemented using Actor::query.