rust/src/test/run-pass/structured-compare.rs

enum foo { large, small, }

impl foo : cmp::Eq {
    pure fn eq(other: &foo) -> bool {
        (self as uint) == ((*other) as uint)
    }
    pure fn ne(other: &foo) -> bool { !self.eq(other) }
}

fn main() {
    let a = (1, 2, 3);
    let b = (1, 2, 3);
    assert (a == b);
    assert (a != (1, 2, 4));
    assert (a < (1, 2, 4));
    assert (a <= (1, 2, 4));
    assert ((1, 2, 4) > a);
    assert ((1, 2, 4) >= a);
    let x = large;
    let y = small;
    assert (x != y);
    assert (x == large);
    assert (x != small);
}