環境

• Rust 1.56.1
• VSCode 1.61.2

概念

參考：https://doc.rust-lang.org/rust-by-example/error/iter_result.html

示例

整個迭代失敗

fn main() {
    let strings = vec!["tofu", "93", "18"];
    let numbers: Result<Vec<_>, _> = strings.into_iter().map(|s| s.parse::<i32>()).collect();
    println!("Results: {:?}", numbers);
}
 

分離成功和失敗

fn main() {
    let strings = vec!["tofu", "93", "18"];
    let (numbers, errors): (Vec<_>, Vec<_>) = strings
        .into_iter()
        .map(|s| s.parse::<i32>())
        .partition(Result::is_ok);
    println!("Numbers: {:?}", numbers);
    println!("Errors: {:?}", errors);
}
 

解開 Result

fn main() {
    let strings = vec!["tofu", "93", "18"];
    let (numbers, errors): (Vec<_>, Vec<_>) = strings
        .into_iter()
        .map(|s| s.parse::<i32>())
        .partition(Result::is_ok);
    let numbers: Vec<_> = numbers.into_iter().map(Result::unwrap).collect();
    let errors: Vec<_> = errors.into_iter().map(Result::unwrap_err).collect();
    println!("Numbers: {:?}", numbers);
    println!("Errors: {:?}", errors);
}
 

總結

瞭解了 Rust 中，迭代的過程中，可以將錯誤的和成功的進行分離，分別取出來。

附錄