rust - 匹配分支中的逻辑 'and'

Question

如何在match的 ARM 中表达逻辑“和”？

如下所示:

fn main() {
    let expr: Result<_, ()> = Ok(String::from("hello"));
    let _res = match expr {
        Ok(s) && s.trim() != "" => s,
        _ => String::from("None"),
    };
}

Answer 1

使用match guard:

fn main() {
    let expr: Result<_, ()> = Ok(String::from("hello"));
    let _res = match expr {
        Ok(s) if s.trim() != "" => s,
        _ => String::from("None"),
    };
}