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| author | Mark Simulacrum <mark.simulacrum@gmail.com> | 2018-06-02 19:55:09 -0600 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2018-06-02 19:55:09 -0600 |
| commit | a689b2d8acd09eed0e471ff75ae301e49b4c436e (patch) | |
| tree | 18c029ea13d8450baef086c05ca16c3066eb4a67 /src/libstd | |
| parent | 5bbe1ebe00428b77708c4d29989be09963ee2880 (diff) | |
| parent | dd88f88c02c901dd14e18a65c0b7132c36f530ee (diff) | |
| download | rust-a689b2d8acd09eed0e471ff75ae301e49b4c436e.tar.gz rust-a689b2d8acd09eed0e471ff75ae301e49b4c436e.zip | |
Rollup merge of #51312 - frewsxcv:clarify-hash-map-entry-get-mut, r=dtolnay
Clarify the difference between get_mut and into_mut for OccupiedEntry The examples for both hash_map::OccupiedEntry::get_mut and hash_map::OccupiedEntry::into_mut were almost identical. This led to some confusion over the difference, namely why you would ever use get_mut when into_mut gives alonger lifetime. Reddit thread: https://www.reddit.com/r/rust/comments/8a5swr/why_does_hashmaps This commit adds two lines and a comment to the example, to show that the entry object can be re-used after calling get_mut. Closes https://github.com/rust-lang/rust/issues/49745
Diffstat (limited to 'src/libstd')
| -rw-r--r-- | src/libstd/collections/hash/map.rs | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs index 935ea4b62b5..5cbd8891364 100644 --- a/src/libstd/collections/hash/map.rs +++ b/src/libstd/collections/hash/map.rs @@ -2250,6 +2250,11 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> { /// Gets a mutable reference to the value in the entry. /// + /// If you need a reference to the `OccupiedEntry` which may outlive the + /// destruction of the `Entry` value, see [`into_mut`]. + /// + /// [`into_mut`]: #method.into_mut + /// /// # Examples /// /// ``` @@ -2261,10 +2266,14 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> { /// /// assert_eq!(map["poneyland"], 12); /// if let Entry::Occupied(mut o) = map.entry("poneyland") { - /// *o.get_mut() += 10; + /// *o.get_mut() += 10; + /// assert_eq!(*o.get(), 22); + /// + /// // We can use the same Entry multiple times. + /// *o.get_mut() += 2; /// } /// - /// assert_eq!(map["poneyland"], 22); + /// assert_eq!(map["poneyland"], 24); /// ``` #[stable(feature = "rust1", since = "1.0.0")] pub fn get_mut(&mut self) -> &mut V { @@ -2274,6 +2283,10 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> { /// Converts the OccupiedEntry into a mutable reference to the value in the entry /// with a lifetime bound to the map itself. /// + /// If you need multiple references to the `OccupiedEntry`, see [`get_mut`]. + /// + /// [`get_mut`]: #method.get_mut + /// /// # Examples /// /// ``` |