Other: Struct duplicate

• This seems to be an old example showing that if we don't compose one struct from another then we have to implement everything in both cases.
• In this case the Circle struct has its own x and y attribute and its own mv method.

struct Point {
    x: i32,
    y: i32,
}

struct Circle {
    x: i32,
    y: i32,
    radius: i32,
}

impl Point {
    fn mv(&mut self, dx: i32, dy: i32) {
        self.x += dx;
        self.y += dy;
    }
}

impl Circle {
    fn mv(&mut self, dx: i32, dy: i32) {
        self.x += dx;
        self.y += dy;
    }
    fn area(&self) -> f32 {
        (self.radius as f32) * (self.radius as f32) * (std::f64::consts::PI as f32)
    }
}

fn main() {
    let mut p = Point { x: 2, y: 3 };
    println!("{}", p.x);
    println!("{}", p.y);
    println!();

    p.mv(4, 5);
    println!("{}", p.x);
    println!("{}", p.y);
    println!("----");

    let mut a = Circle {
        x: 2,
        y: 3,
        radius: 7,
    };
    println!("{}", a.x);
    println!("{}", a.y);
    println!("{}", a.radius);
    println!("{}", a.area());
    println!();

    a.mv(4, 5);
    println!("{}", a.x);
    println!("{}", a.y);
    println!("{}", a.radius);
}

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