I am trying to implement a struct called EventManager that establishes a channel and listens to sends on that channel to add to an internal queue.
The EventManager-
pub enum Event {
Queued(String),
Immediate(String, String)
}
pub struct EventManager {
events: Vec<String>,
receiver: Option<Receiver<Event>>,
}
impl EventManager {
pub fn new() -> EventManager {
let ev = EventManager {
events: Vec::new(),
receiver: None
};
ev
}
pub fn open_channel(&mut self) -> Sender<Event> {
let (tx, rx) = mpsc::channel();
self.receiver = Some(rx);
tx
}
pub fn listen(&mut self) {
let r = self.receiver.as_ref().unwrap();
loop {
match r.recv() {
Ok(Event::Queued(event_string)) => { self.queue(event_string); },
_ => {},
}
}
}
fn queue(&mut self, event_string: String) {
self.events.push(event_string);
}
}
Implementation-
fn main() {
let mut ev = EventManager::new();
let publisher = ev.open_channel();
thread::spawn(move || {
ev.listen();
});
publisher.send(Event::Queued(String::from("Hello")));
}
But this is giving me the compile error-
error[E0502]: cannot borrow `*self` as mutable because it is also borrowed as immutable
--> src\event_manager.rs:34:54
|
30 | let r = self.receiver.as_ref().unwrap();
| ------------- immutable borrow occurs here
...
33 | match r.recv() {
| - immutable borrow later used here
34 | Ok(Event::Queued(event_string)) => { self.queue(event_string); },
| ^^^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
It appears that self.receiver is causing an immutable borrow of self. And later I am trying to make a mutable borrow of self when calling the queue method.
My confusion is why the immutable borrow still exists after I've pulled a field off of it. By the time it gets to self.queue, shouldn't there be no borrowers of self besides the mutable borrow of the method itself?
