Multithreaded trait access

multithreaded-traits.rs

use std::sync::Arc;
use std::sync::RWLock;
use std::task::spawn;
 
trait Common : Sized + Send + Sync {
    fn munge(&mut self);
}

#[deriving(Show)]
struct Foo { i: int }
impl Common for Foo {
    fn munge(&mut self) {
        self.i += 1;
        println!("Munging a Foo: {}", self.i);
    }
}

#[deriving(Show)]
struct Bar { j: int }
impl Common for Bar {
    fn munge(&mut self) {
        self.j += 1;
        println!("Munging a Bar: {}", self.j);
    }
}

fn main() {
    let box1 = Arc::new(RWLock::<Box<Common>>::new(box Foo{i: 0}));
    let box2 = Arc::new(RWLock::<Box<Common>>::new(box Bar{j: 0}));
    for _ in range(0i, 2) {
        // Make new handles for our boxes and pass them to a thread.
        let boxes = vec!(box1.clone(), box2.clone());
        spawn(proc() {
            for b in boxes.iter() {
                b.write().munge();
            }
        });
    }
}