rust/chap5/rectangle.rs


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#[derive(Debug)]
struct Rectangle {
    width:  u32,
    height: u32,
}

impl Rectangle {

    // First parameter for methods must be named 'self', but the
    // implementation provides some aliases like:
    //
    // self  == self: Self
    // &self == self: &Self
    //
    // Note though that 'Self' is just an alias for the type referenced
    // by the impl{} block. So, here:
    //
    // impl Rectangle {}
    //      ^ Self is an alias to Rectangle

    fn can_hold(&self, r: &Rectangle) -> bool {
        self.width > r.width && self.height > r.height
    }
    // Here we can pass just a reference to a struct
    // Rectangle, no need to transfer ownership
    fn area(self: &Rectangle) -> u32 {
        self.width * self.height
    }

    // Associated functions can be defined without a self parameter
    // so they function can be namespaced with ::
    fn square(size: u32) -> Self {
        Self {
            width: size,
            height: size,
        }
    }
}

fn main() {
    let rect = Rectangle {
        width: dbg!(5 * 10),
        height: 3,
    };

    let sqrt = Rectangle::square(90);

    println!("{rect:#?} Area: {}", rect.area());

    dbg!(&rect);
    dbg!(&sqrt);

    println!("{}", sqrt.can_hold(&rect));
}