use std::ops::{Add, Mul, Div, Sub};

fn main() {
    let a = &(&Vec3 { x: 10.0, y: 20.0, z: 30.0 } + 5.0) * 2.0;
    assert_eq!(a, Vec3 { x: 30.0, y: 50.0, z: 70.0 });
}

#[derive(Debug, PartialEq)]
struct Vec3 {
    x: f32,
    y: f32,
    z: f32,
}

macro_rules! impl_for_ref {
    ( $trait:ty, $other:ty, $method:ident, $symb:tt ) => {
        impl $trait for &Vec3 {
            type Output = Vec3;

            fn $method(self, other: $other) -> Vec3 {
                Vec3 {
                    x: self.x $symb other,
                    y: self.y $symb other,
                    z: self.z $symb other,
                }
            }
        }
    };
}

impl_for_ref!(Add<f32>, f32, add, +);
impl_for_ref!(Mul<f32>, f32, mul, *);