drop_trait.rs

#[derive(Debug)]
struct Point {
    x : f64,
}


trait Math : {
    fn sub(&self, &Self) -> Self;
    fn add(&self, &Self) -> Self;
}

impl Math for Point {
    fn add(&self, another : &Point) -> Point {
        Point { x: self.x + another.x }
    }
    fn sub(&self, another : &Point) -> Point {
        Point { x: self.x - another.x }
    }
}

impl Drop for Point {
    fn drop(&mut self) {
        println!("Chao, x = {}", self.x);
    }
}


fn print_math<T>(a : T, b : T) where T: Math + std::fmt::Debug {
    println!("{:?} + {:?} = {:?}", a, b, a.add(&b));
    println!("{:?} - {:?} = {:?}", a, b, a.sub(&b));
}

fn main() {
    let p1 = Point { x: 1.0 };
    let p2 = Point { x: 0.3 };

    print_math(p1, p2);
}