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[SVN r15198]
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Paul Mensonides
2002-09-08 09:40:56 +00:00
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<html>
<head>
<title>BOOST_PP_EMPTY</title>
<link rel="stylesheet" type="text/css" href="../styles.css">
<script language="javascript" type="text/javascript" src="../scripts.js"></script>
</head>
<body onload="init('sample');">
<div style="margin-left: 0px;">
The <b>BOOST_PP_EMPTY</b> macro is a nullary utility macro that expands to nothing.
</div>
<h4>Usage</h4>
<div class="code">
<b>BOOST_PP_EMPTY</b>()
</div>
<h4>Remarks</h4>
<div>
This macro is helps avoid inefficient macro-expansion.&nbsp;
It is primarily useful as arguments to <b>BOOST_PP_IF</b> or <b>BOOST_PP_IIF</b>.
</div>
<h4>Requirements</h4>
<div>
<b>Header:</b> &nbsp;<a href="../headers/facilities/empty.hpp.html">&lt;boost/preprocessor/facilities/empty.hpp&gt;</a>
</div>
<h4><a class="local" onclick="toggle('sample');" onmouseover="change(this);" onmouseout="revert(this);">Sample Code</a></h4>
<div id="sample"><pre>
#include &lt;boost/preprocessor/control/if.hpp&gt;
#include &lt;boost/preprocessor/facilities/empty.hpp&gt;
#define X() result
#define MACRO(c) BOOST_PP_IF(c, X, BOOST_PP_EMPTY)()
MACRO(0) // expands to nothing
MACRO(1) // expands to result
<pre></div>
</body>
</html>