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26 <div class="titlepage"><div><div><h3 class="title">
27 <a name="boost_typetraits.reference.has_trivial_assign"></a><a class="link" href="has_trivial_assign.html" title="has_trivial_assign">has_trivial_assign</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_assign</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>
33 <span class="bold"><strong>Inherits:</strong></span> If T is a (possibly cv-qualified)
34 type with a trivial assignment-operator 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>.
38 If a type has a trivial assignment-operator then the operator has the same
39 effect as copying the bits of one object to the other: calls to the operator
40 can be safely replaced with a call to <code class="computeroutput"><span class="identifier">memcpy</span></code>.
43 <span class="bold"><strong>Compiler Compatibility:</strong></span> If the compiler
44 does not support partial-specialization of class templates, then this template
45 can not be used with function types.
48 Without some (as yet unspecified) help from the compiler, has_trivial_assign
49 will never report that a user-defined class or struct has a trivial constructor;
50 this is always safe, if possibly sub-optimal. Currently (May 2011) compilers
51 more recent than Visual C++ 8, GCC-4.3, Greenhills 6.0, Intel-11.0, and Codegear
52 have the necessary compiler <a class="link" href="../intrinsics.html" title="Support for Compiler Intrinsics">intrinsics</a>
53 to ensure that this trait "just works". You may also test to see
54 if the necessary <a class="link" href="../intrinsics.html" title="Support for Compiler Intrinsics">intrinsics</a>
55 are available by checking to see if the macro <code class="computeroutput"><span class="identifier">BOOST_HAS_TRIVIAL_ASSIGN</span></code>
59 <span class="bold"><strong>C++ Standard Reference:</strong></span> 12.8p11.
62 <span class="bold"><strong>Header:</strong></span> <code class="computeroutput"> <span class="preprocessor">#include</span>
63 <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_assign</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code>
64 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>
67 <span class="bold"><strong>Examples:</strong></span>
69 <div class="blockquote"><blockquote class="blockquote"><p>
70 <code class="computeroutput"><span class="identifier">has_trivial_assign</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span></code>
71 inherits from <code class="computeroutput"><a class="link" href="integral_constant.html" title="integral_constant">true_type</a></code>.
72 </p></blockquote></div>
73 <div class="blockquote"><blockquote class="blockquote"><p>
74 <code class="computeroutput"><span class="identifier">has_trivial_assign</span><span class="special"><</span><span class="keyword">char</span><span class="special">*>::</span><span class="identifier">type</span></code> is the type <code class="computeroutput"><a class="link" href="integral_constant.html" title="integral_constant">true_type</a></code>.
75 </p></blockquote></div>
76 <div class="blockquote"><blockquote class="blockquote"><p>
77 <code class="computeroutput"><span class="identifier">has_trivial_assign</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> is an integral constant expression
78 that evaluates to <span class="emphasis"><em>true</em></span>.
79 </p></blockquote></div>
80 <div class="blockquote"><blockquote class="blockquote"><p>
81 <code class="computeroutput"><span class="identifier">has_trivial_assign</span><span class="special"><</span><span class="identifier">MyClass</span><span class="special">>::</span><span class="identifier">value</span></code> is an integral constant expression
82 that evaluates to <span class="emphasis"><em>false</em></span>.
83 </p></blockquote></div>
84 <div class="blockquote"><blockquote class="blockquote"><p>
85 <code class="computeroutput"><span class="identifier">has_trivial_assign</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">value_type</span></code> is the type <code class="computeroutput"><span class="keyword">bool</span></code>.
86 </p></blockquote></div>
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