use of traits

fmt.rs

use std::fmt;

struct Name {
    first: ~str,
    last: ~str
}

// I'm printing a string here, but 
// in reality this could be binary output
impl fmt::Binary for Name {
    fn fmt(obj: &Name, f: &mut fmt::Formatter) {
        write!(f.buf, "{}, {}", obj.last, obj.first)
    }
}

impl fmt::Default for Name {
    fn fmt(obj: &Name, f: &mut fmt::Formatter) {
        write!(f.buf, "(first: {}, last: {})", obj.first, obj.last)
    }
}

fn main() {
    let x = Name { first: ~"Matthew", last: ~"Philyaw" };
    // print default
    println!("{}", x);
    // print binary
    println!("{:t}", x)
}