projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
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 | ||
| 42 | MACRO(0) // expands to nothing | |
| 43 | MACRO(1) // expands to x | |
| 44 | </pre></div> | |
| 45 | <hr size="1"> | |
| 46 | <div style="margin-left: 0px;"> | |
| 47 |