Methods in Structs

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

impl Rectangle {
		// We are implements area method for the Rectangle struct
    fn area(&self) -> u32 {
        self.width * self.height
    }
}

fn main() {
    let rect1 = Rectangle {
        width: 30,
        height: 50,
    };

    println!(
        "The area of the rectangle is {} square pixels.",
        rect1.area()
    );
}

• Everything within this impl block will be associated with the Rectangle type
• Methods must have a parameter named self of type Self for their first parameter.
• Note that we still need to use the & in front of the self shorthand to indicate that this method borrows the Self instance
• Methods can take ownership of self

Assosiated Functions

All functions defined within an impl block are called associated functions because they’re associated with the type named after the impl. We can define associated functions that don’t have self as their first parameter because they don’t need an instance of the type to work with.

impl Rectangle {
    fn square(size: u32) -> Self {
        Self {
            width: size,
            height: size,
        }
    }
}

fn main() {
	let sq = Rectangle::square(3);
}