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<div class="titlepage"><div><div><h3 class="title">
<a name="boost_typetraits.reference.is_stateless"></a><a class="link" href="is_stateless.html" title="is_stateless"> is_stateless</a>
</h3></div></div></div>
<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>
<span class="keyword">struct</span> <span class="identifier">is_stateless</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>
</pre>
<p>
<span class="bold"><strong>Inherits:</strong></span> Ff T is a stateless type then
inherits from <a class="link" href="integral_constant.html" title="integral_constant">true_type</a>,
otherwise from <a class="link" href="integral_constant.html" title="integral_constant">false_type</a>.
</p>
<p>
Type T must be a complete type.
</p>
<p>
A stateless type is a type that has no storage and whose constructors and
destructors are trivial. That means that <code class="computeroutput"><span class="identifier">is_stateless</span></code>
only inherits from <a class="link" href="integral_constant.html" title="integral_constant">true_type</a>
if the following expression is <code class="computeroutput"><span class="keyword">true</span></code>:
</p>
<pre class="programlisting"><span class="special">::</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">has_trivial_constructor</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">value</span>
<span class="special">&&</span> <span class="special">::</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">has_trivial_copy</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">value</span>
<span class="special">&&</span> <span class="special">::</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">has_trivial_destructor</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">value</span>
<span class="special">&&</span> <span class="special">::</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_class</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">value</span>
<span class="special">&&</span> <span class="special">::</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_empty</span><span class="special"><</span><span class="identifier">T</span><span class="special">>::</span><span class="identifier">value</span>
</pre>
<p>
<span class="bold"><strong>C++ Standard Reference:</strong></span> 3.9p10.
</p>
<p>
<span class="bold"><strong>Header:</strong></span> <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">is_stateless</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code>
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>
</p>
<p>
<span class="bold"><strong>Compiler Compatibility:</strong></span> If the compiler
does not support partial-specialization of class templates, then this template
can not be used with function types.
</p>
<p>
Without some (as yet unspecified) help from the compiler, is_stateless will
never report that a class or struct is stateless; this is always safe, if
possibly sub-optimal. Currently (May 2005) only MWCW 9 and Visual C++ 8 have
the necessary compiler <a class="link" href="../intrinsics.html" title="Support for Compiler Intrinsics">intrinsics</a>
to make this template work automatically.
</p>
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Ramey and Jeremy Siek<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
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>)
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