綁定 - Binding

間接訪問變量使得不可能分支和使用該變量，而無需重新綁定。匹配提供@印記就是出於這樣的目的：

// A function `age` which returns a `u32`.
fn age() -> u32 {
    15
}

fn main() {
    println!("Tell me type of person you are");

    match age() {
        0             => println!("I'm not born yet I guess"),
        // Could `match` 1 ... 12 directly but then what age
        // would the child be? Instead, bind to `n` for the
        // sequence of 1 .. 12. Now the age can be reported.
        n @ 1  ... 12 => println!("I'm a child of age {:?}", n),
        n @ 13 ... 19 => println!("I'm a teen of age {:?}", n),
        // Nothing bound. Return the result.
        n             => println!("I'm an old person of age {:?}", n),
    }
}

也可參考:

函數