1<html> 2<head> 3 <title>BOOST_PP_IDENTITY</title> 4 <link rel="stylesheet" type="text/css" href="../styles.css"> 5</head> 6<body> 7 <div style="margin-left: 0px;"> 8 The <b>BOOST_PP_IDENTITY</b> macro expands to its argument when invoked. 9 </div> 10 <h4>Usage</h4> 11 <div class="code"> 12 <b>BOOST_PP_IDENTITY</b>(<i>item</i>)() 13 </div> 14 <h4>Arguments</h4> 15 <dl> 16 <dt>item</dt> 17 <dd> 18 The result of the expansion. 19 </dd> 20 </dl> 21 <h4>Remarks</h4> 22 <div> 23 This macro is designed to be used with <b>BOOST_PP_IF</b> and <b>BOOST_PP_IIF</b> when only one of the clauses needs to be invoked. 24 </div> 25 <h4>See Also</h4> 26 <ul> 27 <li><a href="if.html">BOOST_PP_IF</a></li> 28 <li><a href="iif.html">BOOST_PP_IIF</a></li> 29 </ul> 30 <h4>Requirements</h4> 31 <div> 32 <b>Header:</b> <a href="../headers/facilities/identity.html"><boost/preprocessor/facilities/identity.hpp></a> 33 </div> 34 <h4>Sample Code</h4> 35<div><pre> 36#include <<a href="../headers/control/if.html">boost/preprocessor/control/if.hpp</a>> 37#include <<a href="../headers/facilities/empty.html">boost/preprocessor/facilities/empty.hpp</a>> 38#include <<a href="../headers/facilities/identity.html">boost/preprocessor/facilities/identity.hpp</a>> 39 40#define MACRO(n) <a href="if.html">BOOST_PP_IF</a>(n, <a href="identity.html">BOOST_PP_IDENTITY</a>(x), <a href="empty.html">BOOST_PP_EMPTY</a>)() 41 42MACRO(0) // expands to nothing 43MACRO(1) // expands to x 44</pre></div> 45 <hr size="1"> 46 <div style="margin-left: 0px;"> 47 <i>� Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i> 48 </br><i>� Copyright Paul Mensonides 2002</i> 49 </div> 50 <div style="margin-left: 0px;"> 51 <p><small>Distributed under the Boost Software License, Version 1.0. (See 52 accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or 53 copy at <a href= 54 "http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p> 55 </div> 56</body> 57</html> 58