t_wの輪郭

多くは前の個体の値を使用しつつ、変更する箇所もある形で新しい個体を生成できる記法

struct User {
    username: String,
    email: String,
    sign_in_count: u64,
    active: bool,
}

fn main() {
    let user1 = User {
        username: String::from("username1"),
        email: String::from("[email protected]"),
        active: true,
        sign_in_count: 1,
    };

    let user2 = User {
        username: String::from("username2"),
        email: String::from("[email protected]"),
        ..user1                                         //構造体更新記法でuser1から残りの欄の値を引き継ぐ
    };

    println!("{}", user2.username);    //username2
}