Rust枚举

枚举可以带方法，本身没什么特别之处：

enum Pet {
    Orca
}

enum HttpStatus{
    Ok = 200
}

元组型变体：

#[derive((Copy,Clone, Debug, PartialEq))]
enum RoughTime {
    InThePast(TimeUnit, u32),
    JustNow,
    InTheFuture(TimeUnit, u32)
}

#[derive(Debug)]
struct Account<'a> {
    name : String,
    language : String,
    num: &'a i32
}
struct Ui{}
impl Ui {
    pub fn new() -> Ui{
        Ui{}
    }
    pub fn greet(&self, name: &String, language: &String) {
        print!("{}{}", name, language);
    }
    pub fn show_setting(&self, account: Account) {
        print!("{:?}", account);
    }
}

#[test]
fn account_test() {
    let account = Account {name:"good".to_string(), language:"china".to_string(), num:&32};
    let ui = Ui::new();
    match account {
        //局部变量name和language是对account中相应字段的引用。由于account只是被借入而没有被消耗，因此继续调用它的方法是没有问题的。
        Account{ref name, ref language, num, ..} => {
            ui.greet(name, language);
            ui.show_setting(account);
            println!("{}", num)
        }
    }
}
struct Engine {
    horsepower: u32,
}

struct CarA {
    engine: Engine,
    color: String,
}

#[test]
fn reference_model(){
    let x = 5;
    let y = &x;

    match y {
        &val => println!("Got a value: {}", val),
    }
}

#[test]
fn car_test(){
    let car = CarA {
        engine: Engine { horsepower: 300 },
        color: String::from("Red"),
    };

    let car_option = Some(&car);

    match car_option {
        Some(&CarA { ref engine, .. }) => {
            println!("The car's engine has {} horsepower.", engine.horsepower);
        }
        None => {
            println!("No car found.");
        }
    }
}
enum ShapeA {
    Rect(Point, Point),
    Circle(Point, u32),
    // 可能还有其他形状...
}

#[test]
fn main_a() {
    let rect = ShapeA::Rect(Point{x:2.0, y:3.0}, Point{x:2.0, y:3.0});
    match rect {
        rect @ ShapeA::Rect (..) => {
            optimized_paint(&rect);
            print!("matched");
        },
        _ => println!("not matched")
    };

}

// 假设的 optimized_paint 函数
fn optimized_paint(shape: &ShapeA) {
    // 实现细节...
}

fn main() {
    let x = 5;
    let y = &x;

    match y {
        ref val => println!("Got a reference to value: {}", val),
    }
}