use std::ops::Add;

#[derive(Debug)]
struct Complex { a: f64, b: f64, }

impl Add for Complex {
    type Output = Complex;
    fn add(self, rhs: Complex) -> Self::Output {
        Complex { a: self.a+rhs.a, b: self.b+rhs.b }
    }
}

fn main() {
    let cp1 = Complex { a: 1f64, b: 2.0 };
    let cp2 = Complex { a: 5.0, b: 8.1 };
    let cp3 = cp1 + cp2;
    println!("{:?}", cp3);
}

add方法的首个参数为什么用self，而不是&self？不解。