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Result::and_then: improve basic example

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cyqsimon 2022-02-12 12:12:11 +08:00
parent 942eaa7ffc
commit 7eaecc6508
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1 changed files with 6 additions and 4 deletions
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10
library/core/src/result.rs
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@ -1282,12 +1282,14 @@ impl<T, E> Result<T, E> {
/// # Examples
///
/// ```
/// fn squared_string(x: u32) -> Result<String, &'static str> {
/// Ok((x * x).to_string())
/// fn sq(x: u32) -> Result<u32, &'static str> {
/// x.checked_mul(x).ok_or("overflowed")
/// }
///
/// assert_eq!(Ok(2).and_then(squared_string), Ok(4.to_string()));
/// assert_eq!(Err("not a number").and_then(squared_string), Err("not a number"));
/// assert_eq!(Ok(2).and_then(sq), Ok(4));
/// assert_eq!(Ok(1_000_000).and_then(sq), Err("overflowed"));
/// assert_eq!(Err("not a number").and_then(sq), Err("not a number"));
/// ```
///
/// Often used to chain fallible operations that may return [`Err`].