gistfile1.txt

iface from_string {
    fn from_string(s: str) -> self;
}

impl of from_string for int {
    fn from_string(s: str) -> int {
        let o = int::from_str(s);
        alt o {
          some(i) { i }
          none { fail; }
        }
    }
}

fn main() {
    log(error, 2.from_string("3"));
}