1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>has_trivial_move_constructor</title> 5<link rel="stylesheet" href="../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../index.html" title="Chapter 1. Boost.TypeTraits"> 8<link rel="up" href="../reference.html" title="Alphabetical Reference"> 9<link rel="prev" href="has_trivial_move_assign.html" title="has_trivial_move_assign"> 10<link rel="next" href="has_unary_minus.html" title="has_unary_minus"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="has_trivial_move_assign.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="has_unary_minus.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h3 class="title"> 27<a name="boost_typetraits.reference.has_trivial_move_constructor"></a><a class="link" href="has_trivial_move_constructor.html" title="has_trivial_move_constructor">has_trivial_move_constructor</a> 28</h3></div></div></div> 29<pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> 30<span class="keyword">struct</span> <span class="identifier">has_trivial_move_constructor</span> <span class="special">:</span> <span class="keyword">public</span> <em class="replaceable"><code><a class="link" href="integral_constant.html" title="integral_constant">true_type</a>-or-<a class="link" href="integral_constant.html" title="integral_constant">false_type</a></code></em> <span class="special">{};</span> 31</pre> 32<p> 33 <span class="bold"><strong>Inherits:</strong></span> If T is a (possibly cv-qualified) 34 type with a trivial move-constructor then inherits from <a class="link" href="integral_constant.html" title="integral_constant">true_type</a>, 35 otherwise inherits from <a class="link" href="integral_constant.html" title="integral_constant">false_type</a>. 36 </p> 37<p> 38 If a type has a trivial move-constructor then the constructor has the same 39 effect as copying the bits of one object to the other: calls to the constructor 40 can be safely replaced with a call to <code class="computeroutput"><span class="identifier">memcpy</span></code>. 41 </p> 42<p> 43 <span class="bold"><strong>Compiler Compatibility:</strong></span> Without some (as 44 yet unspecified) help from the compiler, has_trivial_move_constructor will 45 never report that a user-defined class or struct has a trivial constructor; 46 this is always safe, if possibly sub-optimal. In addition C++11's <code class="computeroutput"><span class="keyword">decltype</span></code> is required to correctly support 47 deleted or private move constructors. Currently (June 2015) compilers that 48 have the necessary <a class="link" href="../intrinsics.html" title="Support for Compiler Intrinsics">intrinsics</a> 49 to ensure that this trait "just works" include Clang, GCC-5.1, 50 and MSVC-12.0. You may also test to see if the necessary <a class="link" href="../intrinsics.html" title="Support for Compiler Intrinsics">intrinsics</a> 51 are available by checking to see if the macro <code class="computeroutput"><span class="identifier">BOOST_HAS_TRIVIAL_MOVE_CONSTRUCTOR</span></code> 52 is defined. 53 </p> 54<p> 55 <span class="bold"><strong>Header:</strong></span> <code class="computeroutput"> <span class="preprocessor">#include</span> 56 <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_traits</span><span class="special">/</span><span class="identifier">has_trivial_move_constructor</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code> 57 or <code class="computeroutput"> <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_traits</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code> 58 </p> 59<p> 60 <span class="bold"><strong>Examples:</strong></span> 61 </p> 62<div class="blockquote"><blockquote class="blockquote"><p> 63 <code class="computeroutput"><span class="identifier">has_trivial_move_constructor</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span></code> inherits from <code class="computeroutput"><a class="link" href="integral_constant.html" title="integral_constant">true_type</a></code>. 64 </p></blockquote></div> 65<div class="blockquote"><blockquote class="blockquote"><p> 66 <code class="computeroutput"><span class="identifier">has_trivial_move_constructor</span><span class="special"><</span><span class="keyword">char</span><span class="special">*>::</span><span class="identifier">type</span></code> 67 is the type <code class="computeroutput"><a class="link" href="integral_constant.html" title="integral_constant">true_type</a></code>. 68 </p></blockquote></div> 69<div class="blockquote"><blockquote class="blockquote"><p> 70 <code class="computeroutput"><span class="identifier">has_trivial_move_constructor</span><span class="special"><</span><span class="keyword">int</span> <span class="special">(*)(</span><span class="keyword">long</span><span class="special">)>::</span><span class="identifier">value</span></code> 71 is an integral constant expression that evaluates to <span class="emphasis"><em>true</em></span>. 72 </p></blockquote></div> 73<div class="blockquote"><blockquote class="blockquote"><p> 74 <code class="computeroutput"><span class="identifier">has_trivial_move_constructor</span><span class="special"><</span><span class="identifier">MyClass</span><span class="special">>::</span><span class="identifier">value</span></code> 75 is an integral constant expression that evaluates to <span class="emphasis"><em>false</em></span>. 76 </p></blockquote></div> 77<div class="blockquote"><blockquote class="blockquote"><p> 78 <code class="computeroutput"><span class="identifier">has_trivial_move_constructor</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">value_type</span></code> 79 is the type <code class="computeroutput"><span class="keyword">bool</span></code>. 80 </p></blockquote></div> 81</div> 82<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 83<td align="left"></td> 84<td align="right"><div class="copyright-footer">Copyright © 2000, 2011 Adobe Systems Inc, David Abrahams, 85 Frederic Bron, Steve Cleary, Beman Dawes, Glen Fernandes, Aleksey Gurtovoy, 86 Howard Hinnant, Jesse Jones, Mat Marcus, Itay Maman, John Maddock, Alexander 87 Nasonov, Thorsten Ottosen, Roman Perepelitsa, Robert Ramey, Jeremy Siek, Robert 88 Stewart and Steven Watanabe<p> 89 Distributed under the Boost Software License, Version 1.0. (See accompanying 90 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 91 </p> 92</div></td> 93</tr></table> 94<hr> 95<div class="spirit-nav"> 96<a accesskey="p" href="has_trivial_move_assign.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="has_unary_minus.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 97</div> 98</body> 99</html> 100
