The Rust Programming Language

The Rust Programming Language — Pattern Matching — Methods

Rust provides us with a way we can define methods on the an enum namespace. It provides us with impl keyword. Methods allow you to call the lines of code in context of certain namespaces. We use methods when the function calls are associated to a particular type, for e.g. enums. Methods are associated functions called on a instance of particular type.

So we have an enum Color and we want to introduce a method to it. We’ll write 2 methods on the enum Color named rgb and new. So we’ll have 2 methods in the scope of Color.

Let’s take a look at below code snippet:

enum Color {
    Red,
    Yellow,
    Green,
    Custom { red: u8, green: u8, blue: u8 }
}

impl Color {
    fn rgb(color: Color) -> (u8, u8, u8) {
        match color {
            Color::Red => (255, 0, 0),
            Color::Yellow => (255, 255, 0),
            Color::Green => (0, 255, 0),
            Color::Custom { red, green, blue } => (red, green, blue)
        }
    }
    fn new(r: u8, g: u8, b: u8) -> Color {
        Color::Custom { red: r, green: g, blue: b }
    }
}

fn main() {
    let current_color: Color = Color::Green;

    let color_description = match current_color {
        Color::Red => {
            "The color is Red!"
        }
        Color::Yellow => {
            "The color is Yellow!"
        }
        _ => {…