gistfile1.rs

trait Strategy<Output> {
    fn send(&self, item: Result<&Output>);
    fn accept(&mut self, sub: &Subscriber<Output>) -> Option<uint>;
}

type Sub<I> = (Subscription, Subscriber<I>);

//This is the most basic strategy which only accepts a single subscriber
struct SingleStrategy<O> {
    subscriber: Option<Sub<O>>,
}

impl<O> SingleStrategy<O> {
    fn new() -> SingleStrategy<O> { SingleStrategy { subscriber: None } }
}

impl<O> SingleStrategy for Strategy<O> {
    pub fn send(&self, item: Result<&O>) {
        self.subscriber.on_next(*item);
    }

    fn accept(&mut self, sub: &Subscriber<O>) -> Option<&Subscription> {
        match self.subscriber {
            Some(_) => { sub.on_error("SubscriptionsFull"); 
                         None }
            None    => { self.sub = (Subscription::new(), sub);
                         sub.on_subscribe(self.sub.ref0());
                         Some(self.sub.ref0) }
        }
    }
}