projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | <html> |
| 2 | <head> | |
| 3 | <title>BOOST_PP_APPLY</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_APPLY</b> macro abstracts the difference between an argument and nothing. | |
| 9 | </div> | |
| 10 | <h4>Usage</h4> | |
| 11 | <div class="code"> | |
| 12 | <b>BOOST_PP_APPLY</b>(<i>x</i>) | |
| 13 | </div> | |
| 14 | <h4>Arguments</h4> | |
| 15 | <dl> | |
| 16 | <dt>x</dt> | |
| 17 | <dd> | |
| 18 | The abstracted argument. | |
| 19 | 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>. | |
| 20 | </dd> | |
| 21 | </dl> | |
| 22 | <h4>Remarks</h4> | |
| 23 | <div> | |
| 24 | If <i>x</i> is <b>BOOST_PP_NIL</b>, this macro expands to nothing. | |
| 25 | If <i>x</i> is a one element <i>tuple</i>, it expands to the contents of that <i>tuple</i>. | |
| 26 | </div> | |
| 27 | <h4>See Also</h4> | |
| 28 | <ul> | |
| 29 | <li><a href="nil.html">BOOST_PP_NIL</a></li> | |
| 30 | </ul> | |
| 31 | <h4>Requirements</h4> | |
| 32 | <div> | |
| 33 | <b>Header:</b> <a href="../headers/facilities/apply.html"><boost/preprocessor/facilities/apply.hpp></a> | |
| 34 | </div> | |
| 35 | <h4>Sample Code</h4> | |
| 36 | <div><pre> | |
| 37 | #include <<a href="../headers/facilities/apply.html">boost/preprocessor/facilities/apply.hpp</a>> | |
| 38 | #include <<a href="../headers/tuple/elem.html">boost/preprocessor/tuple/elem.hpp</a>> | |
| 39 | ||
| 40 | #define CV(i) \ | |
| 41 | <a href="apply.html">BOOST_PP_APPLY</a>( \ | |
| 42 | <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>( \ | |
| 43 | 4, i, \ | |
| 44 | (<a href="nil.html">BOOST_PP_NIL</a>, (const), (volatile), (const volatile)) \ | |
| 45 | ) \ | |
| 46 | ) \ | |
| 47 | /**/ | |
| 48 | ||
| 49 | CV(0) // expands to nothing | |
| 50 | CV(1) // expands to const | |
| 51 | </pre></div> | |
| 52 | <hr size="1"> | |
| 53 | <div style="margin-left: 0px;"> | |
| 54 |