diff options
| author | pkasting <pkasting@chromium.org> | 2016-02-04 14:14:36 -0800 |
|---|---|---|
| committer | Commit bot <commit-bot@chromium.org> | 2016-02-04 22:16:05 +0000 |
| commit | 53121c429fda1499dfd68ae9ac27c4c51de16aa0 (patch) | |
| tree | 0d2a39c4296d6a28ce883b8a1b50085314b1afd5 /styleguide/c++/c++11.html | |
| parent | b61d4dee1b0e98e2b5c0fba66c5ad4b1335c02fe (diff) | |
| download | chromium_src-53121c429fda1499dfd68ae9ac27c4c51de16aa0.zip chromium_src-53121c429fda1499dfd68ae9ac27c4c51de16aa0.tar.gz chromium_src-53121c429fda1499dfd68ae9ac27c4c51de16aa0.tar.bz2 | |
Allow emplacement methods for containers, with some cautions.
BUG=none
TEST=none
Review URL: https://codereview.chromium.org/1664943003
Cr-Commit-Position: refs/heads/master@{#373637}
Diffstat (limited to 'styleguide/c++/c++11.html')
| -rw-r--r-- | styleguide/c++/c++11.html | 19 |
1 files changed, 8 insertions, 11 deletions
diff --git a/styleguide/c++/c++11.html b/styleguide/c++/c++11.html index 8a6ea1d..cccae2e 100644 --- a/styleguide/c++/c++11.html +++ b/styleguide/c++/c++11.html @@ -383,6 +383,14 @@ std::end</a></td> </tr> <tr> +<td>Emplacement methods for containers</td> +<td><code>emplace()</code>, <code>emplace_back()</code>, <code>emplace_front()</code>, <code>emplace_hint()</code></td> +<td>Constructs elements directly within a container without a copy or a move. Less verbose than <code>push_back()</code> due to not naming the type being constructed.</td> +<td>E.g. <a href="http://en.cppreference.com/w/cpp/container/vector/emplace_back">std::vector::emplace_back</a></td> +<td><code>std::map::emplace()</code> is not yet available on all libstdc++ versions we support. When using emplacement for performance reasons, your type should probably be movable (since e.g. a vector of it might be resized); given a movable type, then, consider whether you really need to avoid the move done by <code>push_back()</code>. For readability concerns, treat like <code>auto</code>; sometimes the brevity over <code>push_back()</code> is a win, sometimes a loss. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/cxx/m3cblzEta7A">Discussion thread</a></td> +</tr> + +<tr> <td>Forwarding references</td> <td><code>std::forward()</code></td> <td>Perfectly forwards arguments (including rvalues)</td> @@ -835,17 +843,6 @@ the <code><complex></code> library.</td> </tr> <tr> -<td>Construct Elements in Containers</td> -<td><code>emplace()</code>,<code>emplace_back()</code>, -<code>emplace_front()</code>, <code>emplace_hint()</code></td> -<td>Constructs elements directly within a container without a copy -or a move</td> -<td>TODO: documentation link</td> -<td>Use where element construction within a container -is needed.</td> -</tr> - -<tr> <td>Container Compaction Functions</td> <td><code>std::vector::shrink_to_fit()</code>, <code>std::deque::shrink_to_fit()</code>, and |