Chromium Code Reviews Chromium Code Reviews
Issue 1499293002:
Move Rvalue references to the allowed section of the C++11 styleguide. (Closed)
Base URL: https://chromium.googlesource.com/chromium/src.git@master| OLD | NEW |
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| 1 <!DOCTYPE html> | 1 <!DOCTYPE html> |
| 2 <!-- | 2 <!-- |
| 3 Copyright 2014 The Chromium Authors. All rights reserved. | 3 Copyright 2014 The Chromium Authors. All rights reserved. |
| 4 Use of this source code is governed by a BSD-style license that can be | 4 Use of this source code is governed by a BSD-style license that can be |
| 5 found in the LICENSE file. | 5 found in the LICENSE file. |
| 6 --> | 6 --> |
| 7 <html> | 7 <html> |
| 8 <head> | 8 <head> |
| 9 <meta charset="utf-8"> | 9 <meta charset="utf-8"> |
| 10 <title>C++11 use in Chromium</title> | 10 <title>C++11 use in Chromium</title> |
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| 238 <td>Range-Based For Loops</td> | 238 <td>Range-Based For Loops</td> |
| 239 <td><code>for (<i>type</i> <i>var</i> : <i>range</i>)</code></td> | 239 <td><code>for (<i>type</i> <i>var</i> : <i>range</i>)</code></td> |
| 240 <td>Facilitates a more concise syntax for iterating over the elements | 240 <td>Facilitates a more concise syntax for iterating over the elements |
| 241 of a container (or a range of iterators) in a <code>for</code> loop</td> | 241 of a container (or a range of iterators) in a <code>for</code> loop</td> |
| 242 <td><a href="http://en.cppreference.com/w/cpp/language/range-for"> | 242 <td><a href="http://en.cppreference.com/w/cpp/language/range-for"> |
| 243 Range-based for loop</a></td> | 243 Range-based for loop</a></td> |
| 244 <td>As a rule of thumb, use <code>for (const auto& ...)</code>, <code>for (auto& ...)</code>, or <code>for (<i>concrete type</i> ...)</code>. For pointers, use <code>for (auto* ...)</code> to make clear that the copy of the loop variable is intended, and only a pointer is copied. <a href="https://groups.google.com/a/ch romium.org/forum/#!topic/chromium-dev/hpzz4EqbVmc">Discussion thread</a></td> | 244 <td>As a rule of thumb, use <code>for (const auto& ...)</code>, <code>for (auto& ...)</code>, or <code>for (<i>concrete type</i> ...)</code>. For pointers, use <code>for (auto* ...)</code> to make clear that the copy of the loop variable is intended, and only a pointer is copied. <a href="https://groups.google.com/a/ch romium.org/forum/#!topic/chromium-dev/hpzz4EqbVmc">Discussion thread</a></td> |
| 245 </tr> | 245 </tr> |
| 246 | 246 |
| 247 <tr> | 247 <tr> |
| 248 <td>Rvalue References</td> | |
| 249 <td><code>T(T&& t)</code> and <code>T& operator=(T&& t)</cod e><br/> | |
| 250 <code>template <typename T>void Function(T&& t) { ... }</code></td> | |
| 251 <td>Reference that only binds to a temporary object</td> | |
| 252 <td><a href="http://en.cppreference.com/w/cpp/language/references#Rvalue_referen ces"> | |
| 253 Rvalue references</a></td> | |
| 254 <td>As per the <a href="https://google.github.io/styleguide/cppguide.html#Rvalue _references">Google style guide</a>: Only use these to define move constructors and move assignment operators, and for perfect forwarding.<br/>Most classes shou ld not be copyable, even if movable. Continue to use DISALLOW_COPY_AND_ASSIGN (o r DISALLOW_COPY_AND_ASSIGN_WITH_MOVE_FOR_BIND if needed) in most cases. <a href= "https://groups.google.com/a/chromium.org/d/topic/chromium-dev/UnRaORb4TSw">Disc ussion thread</a> and <a href="https://groups.google.com/a/chromium.org/d/topic/ cxx/Q526tkruXpM">discussion thread</a>.</td> | |
|
Nico
2015/12/07 19:00:35
Should we list the MSVC bugs we know about here to
danakj
2015/12/07 19:08:27
Done! (I only remember 2, do you remember more?)
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| 255 </tr> | |
| 256 | |
| 257 <tr> | |
| 248 <td>Standard Integers</td> | 258 <td>Standard Integers</td> |
| 249 <td>Typedefs within <code><stdint.h></code> | 259 <td>Typedefs within <code><stdint.h></code> |
| 250 and <code><inttypes></code></td> | 260 and <code><inttypes></code></td> |
| 251 <td>Provides fixed-size integers independent of platforms</td> | 261 <td>Provides fixed-size integers independent of platforms</td> |
| 252 <td><a href="http://www.cplusplus.com/reference/cstdint/"> | 262 <td><a href="http://www.cplusplus.com/reference/cstdint/"> |
| 253 <stdint.h> (cstdint)</a></td> | 263 <stdint.h> (cstdint)</a></td> |
| 254 <td>Already in common use in the codebase. Approved without discussion.</td> | 264 <td>Already in common use in the codebase. Approved without discussion.</td> |
| 255 </tr> | 265 </tr> |
| 256 | 266 |
| 257 <tr> | 267 <tr> |
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| 333 <td><a href="http://en.cppreference.com/w/cpp/utility/tuple/tie">std::tie</a></t d> | 343 <td><a href="http://en.cppreference.com/w/cpp/utility/tuple/tie">std::tie</a></t d> |
| 334 <td>General use of <code>std::tuple</code>, and <code>std::tie</code> for unpack ing or multiple assignments is still not allowed. <a href="https://groups.google .com/a/chromium.org/d/topic/cxx/3DZ64dIMRTY/discussion">Discussion thread</a></t d> | 344 <td>General use of <code>std::tuple</code>, and <code>std::tie</code> for unpack ing or multiple assignments is still not allowed. <a href="https://groups.google .com/a/chromium.org/d/topic/cxx/3DZ64dIMRTY/discussion">Discussion thread</a></t d> |
| 335 </tr> | 345 </tr> |
| 336 | 346 |
| 337 <tr> | 347 <tr> |
| 338 <td>Move Semantics</td> | 348 <td>Move Semantics</td> |
| 339 <td><code>std::move()</code></td> | 349 <td><code>std::move()</code></td> |
| 340 <td>Facilitates efficient move operations</td> | 350 <td>Facilitates efficient move operations</td> |
| 341 <td><a href="http://en.cppreference.com/w/cpp/utility/move"> | 351 <td><a href="http://en.cppreference.com/w/cpp/utility/move"> |
| 342 <code>std::move</code> reference</a></td> | 352 <code>std::move</code> reference</a></td> |
| 343 <td>Note: std::move() is allowed but writing your own move constructors is still only allowed in exceptional cases for now, see 'Rvalue References (and Move Sem antics)'. <a href='https://groups.google.com/a/chromium.org/forum/#!topic/cxx/x_ dWFxJFdbM'>Discussion thread</a></td> | 353 <td><a href='https://groups.google.com/a/chromium.org/forum/#!topic/cxx/x_dWFxJF dbM'>Discussion thread</a></td> |
| 344 </tr> | 354 </tr> |
| 345 | 355 |
| 346 <tr> | 356 <tr> |
| 347 <td>Conditional Type Selection</td> | 357 <td>Conditional Type Selection</td> |
| 348 <td><code>std::enable_if</code> and <code>std::conditional</code></td> | 358 <td><code>std::enable_if</code> and <code>std::conditional</code></td> |
| 349 <td>Enables compile-time conditional type selection</td> | 359 <td>Enables compile-time conditional type selection</td> |
| 350 <td><a href="http://en.cppreference.com/w/cpp/types/enable_if"> | 360 <td><a href="http://en.cppreference.com/w/cpp/types/enable_if"> |
| 351 std::enable_if</a> and | 361 std::enable_if</a> and |
| 352 <a href="http://en.cppreference.com/w/cpp/types/conditional"> | 362 <a href="http://en.cppreference.com/w/cpp/types/conditional"> |
| 353 conditional</a></td> | 363 conditional</a></td> |
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| 451 <td>Raw String Literals</td> | 461 <td>Raw String Literals</td> |
| 452 <td><code>string <i>var</i>=R"(<i>raw_string</i>)";</code></td> | 462 <td><code>string <i>var</i>=R"(<i>raw_string</i>)";</code></td> |
| 453 <td>Allows a string to be encoded without any escape | 463 <td>Allows a string to be encoded without any escape |
| 454 sequences, easing parsing in regex expressions, for example</td> | 464 sequences, easing parsing in regex expressions, for example</td> |
| 455 <td><a href="http://en.cppreference.com/w/cpp/language/string_literal"> | 465 <td><a href="http://en.cppreference.com/w/cpp/language/string_literal"> |
| 456 string literal</a></td> | 466 string literal</a></td> |
| 457 <td>Causes incorrect line numbers in MSVS2013 and gcc. Reevaluate once that work s. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/ 2kWQHbbuMHI">Discussion thread</a></td> | 467 <td>Causes incorrect line numbers in MSVS2013 and gcc. Reevaluate once that work s. <a href="https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/ 2kWQHbbuMHI">Discussion thread</a></td> |
| 458 </tr> | 468 </tr> |
| 459 | 469 |
| 460 <tr> | 470 <tr> |
| 461 <td>Rvalue References (and Move Semantics)</td> | |
| 462 <td><code>T(T&& t)</code> and <code>T& operator=(T&& t)</cod e></td> | |
| 463 <td>Reference that only binds to a temporary object</td> | |
| 464 <td><a href="http://en.cppreference.com/w/cpp/language/references#Rvalue_referen ces"> | |
| 465 Rvalue references</a></td> | |
| 466 <td>To be revisited in the future. Allowed in exceptional cases where approved by the OWNERS of src/styleguide/c++/. <a href="https://groups.google.com/a/chrom ium.org/d/topic/chromium-dev/UnRaORb4TSw">Discussion thread</a></td> | |
| 467 </tr> | |
| 468 | |
| 469 <tr> | |
| 470 <td>(Uniform) Initialization Syntax</td> | 471 <td>(Uniform) Initialization Syntax</td> |
| 471 <td><code><i>type</i> <i>name</i> { [<i>value</i> ..., <i>value</i>]};</code></t d> | 472 <td><code><i>type</i> <i>name</i> { [<i>value</i> ..., <i>value</i>]};</code></t d> |
| 472 <td>Allows any object of primitive, aggregate or class | 473 <td>Allows any object of primitive, aggregate or class |
| 473 type to be initialized using brace syntax</td> | 474 type to be initialized using brace syntax</td> |
| 474 <td>TODO: documentation link</td> | 475 <td>TODO: documentation link</td> |
| 475 <td>Dangerous without library support, see thread. Reevaulate once we have C++11 library support. <a href="https://groups.google.com/a/chromium.org/forum/#!topi c/chromium-dev/GF96FshwHLw">Discussion thread</a></td> | 476 <td>Dangerous without library support, see thread. Reevaulate once we have C++11 library support. <a href="https://groups.google.com/a/chromium.org/forum/#!topi c/chromium-dev/GF96FshwHLw">Discussion thread</a></td> |
| 476 </tr> | 477 </tr> |
| 477 | 478 |
| 478 <tr> | 479 <tr> |
| 479 <td>UTF-16 and UTF-32 Support (16-Bit and 32-Bit Character Types)</td> | 480 <td>UTF-16 and UTF-32 Support (16-Bit and 32-Bit Character Types)</td> |
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| 1068 C++ Style Guide</a>. However, may be useful for | 1069 C++ Style Guide</a>. However, may be useful for |
| 1069 consuming non-ASCII data.</td> | 1070 consuming non-ASCII data.</td> |
| 1070 </tr> | 1071 </tr> |
| 1071 | 1072 |
| 1072 </tbody> | 1073 </tbody> |
| 1073 </table> | 1074 </table> |
| 1074 | 1075 |
| 1075 </div> | 1076 </div> |
| 1076 </body> | 1077 </body> |
| 1077 </html> | 1078 </html> |
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