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<td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./metafunctions.html" class="navigation-link">Metafunctions</a> / <a href="./miscellaneous.html" class="navigation-link">Miscellaneous</a> / <a href="./always.html" class="navigation-link">always</a></td>
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<div class="section" id="always">
<h1><a class="toc-backref" href="./miscellaneous.html#id1565">always</a></h1>
<div class="section" id="id1155">
<h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3>
<pre class="literal-block">
template&lt;
      typename X
    &gt;
struct <a href="./always.html" class="identifier">always</a>
{
    // <em>unspecified</em>
    // <em>...</em>
};
</pre>
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<div class="section" id="id1156">
<h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
<p><tt class="literal"><span class="pre"><a href="./always.html" class="identifier">always</a>&lt;X&gt;</span></tt> specialization is a variadic <a class="reference internal" href="./metafunction-class.html">Metafunction Class</a> always returning the
same type, <tt class="literal"><span class="pre">X</span></tt>, regardless of the number and types of passed arguments.</p>
</div>
<div class="section" id="id1157">
<h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
<pre class="literal-block">
#include &lt;<a href="../../../../boost/mpl/always.hpp" class="header">boost/mpl/always.hpp</a>&gt;
</pre>
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<div class="section" id="id1158">
<h3><a class="subsection-title" href="#model-of" name="model-of">Model of</a></h3>
<p><a class="reference internal" href="./metafunction-class.html">Metafunction Class</a></p>
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<div class="section" id="id1159">
<h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
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<tr><th class="head">Parameter</th>
<th class="head">Requirement</th>
<th class="head">Description</th>
</tr>
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<tbody valign="top">
<tr><td><tt class="literal"><span class="pre">X</span></tt></td>
<td>Any type</td>
<td>A type to be returned.</td>
</tr>
</tbody>
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</div>
<div class="section" id="id1160">
<h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
<p>For an arbitrary type <tt class="literal"><span class="pre">x</span></tt>:</p>
<pre class="literal-block">
typedef <a href="./always.html" class="identifier">always</a>&lt;x&gt; f;
</pre>
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<tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first"><a class="reference internal" href="./metafunction-class.html">Metafunction Class</a>.</p>
</td>
</tr>
<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p>
<pre class="last literal-block">
struct f : <a href="./bind.html" class="identifier">bind</a>&lt; <a href="./identity.html" class="identifier">identity</a>&lt;<a href="./placeholders.html" class="identifier">_1</a>&gt;, x > {};
</pre>
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<div class="section" id="id1161">
<h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
<pre class="literal-block">
typedef <a href="./always.html" class="identifier">always</a>&lt;<a href="./bool.html" class="identifier">true_</a>&gt; always_true;

<a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./apply.html" class="identifier">apply</a>&lt; always_true,<a href="./bool.html" class="identifier">false_</a>&gt; ));
<a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./apply.html" class="identifier">apply</a>&lt; always_true,<a href="./bool.html" class="identifier">false_</a>,<a href="./bool.html" class="identifier">false_</a> &gt; ));
<a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./apply.html" class="identifier">apply</a>&lt; always_true,<a href="./bool.html" class="identifier">false_</a>,<a href="./bool.html" class="identifier">false_</a>,<a href="./bool.html" class="identifier">false_</a> > ));
</pre>
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<div class="section" id="id1162">
<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
<p><a class="reference internal" href="./metafunctions.html">Metafunctions</a>, <a class="reference internal" href="./metafunction-class.html">Metafunction Class</a>, <a class="reference internal" href="./identity.html">identity</a>, <a class="reference internal" href="./bind.html">bind</a>, <a class="reference internal" href="./apply.html">apply</a></p>
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