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Recommends lazily evaluated alternatives for Option::or and Result::or #46548

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Merged
merged 2 commits into from
Dec 8, 2017
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Recommends lazily evaluated alternatives for Option::or and Result::or #46548

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9307917
Adds language to the documentation for `Option` and `Result` suggesting
Dec 7, 2017
5847d0b
adds links to methods, removes trailing whitespace
Dec 7, 2017
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12 changes: 12 additions & 0 deletions src/libcore/option.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -338,6 +338,10 @@ impl<T> Option<T> {

/// Returns the contained value or a default.
///
/// Arguments passed to `unwrap_or` are eagerly evaluated; if you are passing
/// the result of a function call, it is recommended to use `unwrap_or_else`,
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Could you link to the unwrap_or_else method? i.e.

/// ... it is recommended to use [`unwrap_or_else`],
///
/// ...
///
/// [`unwrap_or_else`]: #method.unwrap_or_else

Similar for the other additions.

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sure - will do

/// which is lazily evaluated.
///
/// # Examples
///
/// ```
Expand Down Expand Up @@ -451,6 +455,10 @@ impl<T> Option<T> {
/// Transforms the `Option<T>` into a [`Result<T, E>`], mapping [`Some(v)`] to
/// [`Ok(v)`] and [`None`] to [`Err(err)`].
///
/// Arguments passed to `ok_or` are eagerly evaluated; if you are passing the
/// result of a function call, it is recommended to use `ok_or_else`, which is
/// lazily evaluated.
///
/// [`Result<T, E>`]: ../../std/result/enum.Result.html
/// [`Ok(v)`]: ../../std/result/enum.Result.html#variant.Ok
/// [`Err(err)`]: ../../std/result/enum.Result.html#variant.Err
Expand Down Expand Up @@ -609,6 +617,10 @@ impl<T> Option<T> {

/// Returns the option if it contains a value, otherwise returns `optb`.
///
/// Arguments passed to `or` are eagerly evaluated; if you are passing the
/// result of a function call, it is recommended to use `or_else`, which is
/// lazily evaluated.
///
/// # Examples
///
/// ```
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8 changes: 8 additions & 0 deletions src/libcore/result.rs
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Expand Up @@ -625,6 +625,10 @@ impl<T, E> Result<T, E> {

/// Returns `res` if the result is [`Err`], otherwise returns the [`Ok`] value of `self`.
///
/// Arguments passed to `or` are eagerly evaluated; if you are passing the
/// result of a function call, it is recommended to use `or_else`, which is
/// lazily evaluated.
///
/// [`Ok`]: enum.Result.html#variant.Ok
/// [`Err`]: enum.Result.html#variant.Err
///
Expand Down Expand Up @@ -690,6 +694,10 @@ impl<T, E> Result<T, E> {
/// Unwraps a result, yielding the content of an [`Ok`].
/// Else, it returns `optb`.
///
/// Arguments passed to `unwrap_or` are eagerly evaluated; if you are passing
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There is a trailing whitespace on this line, causing the CI to reject this PR. Other places affected:

[00:04:39] tidy error: /checkout/src/libcore/result.rs:697: trailing whitespace
[00:04:39] tidy error: /checkout/src/libcore/result.rs:698: trailing whitespace
[00:04:39] tidy error: /checkout/src/libcore/result.rs:699: trailing whitespace
[00:04:39] tidy error: /checkout/src/libcore/option.rs:341: trailing whitespace
[00:04:39] tidy error: /checkout/src/libcore/option.rs:342: trailing whitespace
[00:04:39] tidy error: /checkout/src/libcore/option.rs:343: trailing whitespace
[00:04:41] some tidy checks failed

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fixed

/// the result of a function call, it is recommended to use `unwrap_or_else`,
/// which is lazily evaluated.
///
/// [`Ok`]: enum.Result.html#variant.Ok
/// [`Err`]: enum.Result.html#variant.Err
///
Expand Down