Dynamic tuple access in Rust

main.rs

use std::{rc::Rc, cell::RefCell};

macro_rules! nth {
  ($tuple:expr, $axis:tt) => {
    match $axis {
      0 => $tuple.0,
      1 => $tuple.1,
      _ => unreachable!()
    }
  }
}

struct Limit {
  vector: Rc<RefCell<(i32, i32)>>,
  limit: i32,
  axis: u8
}

impl Limit {
  fn is_out(&self) -> bool {
    let axis = self.axis;
    nth!((*self.vector).borrow(), axis) > self.limit
	}
}

fn main() {
  let vecref = Rc::new(RefCell::new((0, 0)));
  let limit_x = Limit { vector: vecref.clone(), limit: 250, axis: 0 }; 
  let limit_y = Limit { vector: vecref.clone(), limit: 800, axis: 1 }; 
  for _ in 0..5 {
    vecref.borrow_mut().0 += 100;
    vecref.borrow_mut().1 += 200;
    if limit_x.is_out() || limit_y.is_out() {
      println!("Position {:?} is out of bounds. Resetting position", vecref);
      *vecref.borrow_mut() = (0,0);
    }
  }
}