associated-fields.rs

// I'm not sure how much the Copy bound is actually necessary...

trait LeftRight<T: Copy> {
  left: T,
  right: T
}

impl<C: Copy, LR: LeftRight<C>, T: LR> T {
  fn swap(&mut self) {
    let temp = self.right;
    self.right = self.left;
    self.left = temp;
  }
}

#[impl(Debug, Clone, Copy)]
struct IntPair(i32, i32);

impl LeftRight<i32> for IntPair {
  left = self.0,
  right = self.1
}

fn main () {
  let mut numbers = IntPair(0i32, 1i32);
  numbers.swap();
  println!("{:?}", numbers);
}