Rust на примерах

При работе метода Iter::map может случиться ошибка, например:

fn main() {

let strings = vec!["tofu", "93", "18"];

let numbers: Vec<_> = strings

.into_iter()

.map(|s| s.parse::())

.collect();

println!("Результаты: {:?}", numbers);

}

הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה

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Давайте рассмотрим стратегии обработки этого.

Игнорирование неудачных элементов с filter_map()

filter_map вызывает функцию и отфильтровывает результаты, вернувшие None.

fn main() {

let strings = vec!["tofu", "93", "18"];

let numbers: Vec<_> = strings

.into_iter()

.map(|s| s.parse::())

.filter_map(Result::ok)

.collect();

println!("Результаты: {:?}", numbers);

}

הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה

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Сбой всей операции с collect()

Result реализует FromIter так что вектор из результатов (Vec>) может быть преобразован в результат с вектором (Result, E>). Если будет найдена хотя бы одна Result::Err, итерирование завершится.

fn main() {

let strings = vec!["tofu", "93", "18"];

let numbers: Result, _> = strings

.into_iter()

.map(|s| s.parse::())

.collect();

println!("Результаты: {:?}", numbers);

}

הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה

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Та же самая техника может использоваться с Option.

Сбор всех корректных значений и ошибок с помощью partition()

fn main() {

let strings = vec!["tofu", "93", "18"];

let (numbers, errors): (Vec<_>, Vec<_>) = strings

.into_iter()

.map(|s| s.parse::())

.partition(Result::is_ok);

println!("Числа: {:?}", numbers);

println!("Ошибки: {:?}", errors);

}

הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה

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Если вы посмотрите на результаты работы, вы заметите, что они всё ещё обёрнуты в Result. Потребуется немного больше шаблонного кода, чтобы получить нужный результат.

fn main() {

let strings = vec!["tofu", "93", "18"];

let (numbers, errors): (Vec<_>, Vec<_>) = strings

.into_iter()

.map(|s| s.parse::())

.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!("Числа: {:?}", numbers);

println!("Ошибки: {:?}", errors);

}

הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה

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