ceph/src/boost/libs/preprocessor/doc/ref/comma_if.html

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   3         <title>BOOST_PP_COMMA_IF</title>
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   8                 The <b>BOOST_PP_COMMA_IF</b> macro conditionally expands to a comma.
   9         </div>
  10         <h4>Usage</h4>
  11                 <div class="code">
  12                         <b>BOOST_PP_COMMA_IF</b>(<i>cond</i>)
  13                 </div>
  14         <h4>Arguments</h4>
  15                 <dl>
  16                         <dt>cond</dt>
  17                         <dd>
  18                                 The condition that determines if a the macro expands to a comma or nothing.&nbsp;
  19                                 Valid values range from <i>0</i> to <b>BOOST_PP_LIMIT_MAG</b>.
  20                         </dd>
  21                 </dl>
  22         <h4>Remarks</h4>
  23                 <div>
  24                         If <i>cond</i> expands to <i>0</i>, this macro expands to nothing.&nbsp;
  25                         Otherwise, it expands to a comma.
  26                 </div>
  27                 <div>
  28                         The preprocessor interprets commas as argument separators in macro invocations.&nbsp;
  29                         Because of this, commas require special handling.
  30                 </div>
  31         <h4>See Also</h4>
  32                 <ul>
  33                         <li><a href="limit_mag.html">BOOST_PP_LIMIT_MAG</a></li>
  34                 </ul>
  35         <h4>Requirements</h4>
  36                 <div>
  37                         <b>Header:</b> &nbsp;<a href="../headers/punctuation/comma_if.html">&lt;boost/preprocessor/punctuation/comma_if.hpp&gt;</a>
  38                 </div>
  39         <h4>Sample Code</h4>
  40 <div><pre>
  41 #include &lt;<a href="../headers/punctuation/comma_if.html">boost/preprocessor/punctuation/comma_if.hpp</a>&gt;
  42 #include &lt;<a href="../headers/repetition/repeat.html">boost/preprocessor/repetition/repeat.hpp</a>&gt;
  43
  44 #define MACRO(z, n, text) <a href="comma_if.html">BOOST_PP_COMMA_IF</a>(n) text
  45
  46 <a href="repeat.html">BOOST_PP_REPEAT</a>(3, MACRO, class) // expands to class, class, class
  47 </pre></div>
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  50                 <i>© Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i>
  51                 </br><i>© Copyright Paul Mensonides 2002</i>
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  53         <div style="margin-left: 0px;">
  54                 <p><small>Distributed under the Boost Software License, Version 1.0. (See
  55                 accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
  56                 copy at <a href=
  57                 "http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
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