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<html>
<head>
<title>BOOST_PP_APPLY</title>
<link rel="stylesheet" type="text/css" href="../styles.css">
</head>
<body>
<div style="margin-left: 0px;">
The <b>BOOST_PP_APPLY</b> macro abstracts the difference between an argument and nothing.
</div>
<h4>Usage</h4>
<div class="code">
<b>BOOST_PP_APPLY</b>(<i>x</i>)
</div>
<h4>Arguments</h4>
<dl>
<dt>x</dt>
<dd>
The abstracted argument.
This argument must be either <b>BOOST_PP_NIL</b> or a <i>tuple</i> with one element--such as <i>(arg)</i> or <i>((a, b))</i>.
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</dl>
<h4>Remarks</h4>
<div>
If <i>x</i> is <b>BOOST_PP_NIL</b>, this macro expands to nothing.
If <i>x</i> is a one element <i>tuple</i>, it expands to the contents of that <i>tuple</i>.
</div>
<h4>See Also</h4>
<ul>
<li><a href="nil.html">BOOST_PP_NIL</a></li>
</ul>
<h4>Requirements</h4>
<div>
<b>Header:</b> <a href="../headers/facilities/apply.html"><boost/preprocessor/facilities/apply.hpp></a>
</div>
<h4>Sample Code</h4>
<div><pre>
#include <<a href="../headers/facilities/apply.html">boost/preprocessor/facilities/apply.hpp</a>>
#include <<a href="../headers/tuple/elem.html">boost/preprocessor/tuple/elem.hpp</a>>
#define CV(i) \
<a href="apply.html">BOOST_PP_APPLY</a>( \
<a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>( \
4, i, \
(<a href="nil.html">BOOST_PP_NIL</a>, (const), (volatile), (const volatile)) \
) \
) \
/**/
CV(0) // expands to nothing
CV(1) // expands to const
</pre></div>
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