projects / ceph.git / blame
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1 | <html> |
| 2 | <head> | |
| 3 | <title>BOOST_PP_TUPLE_ELEM</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_TUPLE_ELEM</b> macro extracts an element from a <i>tuple</i>. | |
| 9 | </div> | |
| 10 | <h4>Usage</h4> | |
| 11 | <div class="code"> | |
| 12 | <b>BOOST_PP_TUPLE_ELEM</b>(<i>size</i>, <i>i</i>, <i>tuple</i>)<sup></sup><br> | |
| 13 | <br> | |
| 14 | or<br> | |
| 15 | <br> | |
| 16 | <b>BOOST_PP_TUPLE_ELEM</b>(<i>...</i>) <a href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a><b></b><br> | |
| 17 | </div> | |
| 18 | <h4>Arguments</h4> | |
| 19 | <dl> | |
| 20 | <dt>size</dt> | |
| 21 | <dd> | |
| 22 | The size of the <i>tuple</i>. | |
| 23 | Valid <i>tuple</i> sizes range from <i>1</i> to <b>BOOST_PP_LIMIT_TUPLE</b>. | |
| 24 | </dd> | |
| 25 | <dt>i</dt> | |
| 26 | <dd> | |
| 27 | The zero-based index into the <i>tuple</i> of the element to be extracted. | |
| 28 | Valid values range from <i>0</i> to <i>size</i> - <i>1</i>. | |
| 29 | </dd> | |
| 30 | <dt>tuple</dt> | |
| 31 | <dd> | |
| 32 | The <i>tuple</i> from which an element is to be extracted. | |
| 33 | </dd> | |
| 34 | </dl> | |
| 35 | <h4>Remarks</h4> | |
| 36 | <div> | |
| 37 | The <i>size</i> argument must be the actual size of the <i>tuple</i>, | |
| 38 | and <i>i</i> must be less than the size of the <i>tuple</i>. <br> | |
| 39 | <br>You can | |
| 40 | invoke the variadic version as BOOST_PP_TUPLE_ELEM(<i>i</i>,<i>tuple</i>) or | |
| 41 | BOOST_PP_TUPLE_ELEM(<i>size</i>,<i>i</i>,<i>tuple</i>). | |
| 42 | </div> | |
| 43 | <h4>See Also</h4> | |
| 44 | <ul> | |
| 45 | <li><a href="limit_tuple.html">BOOST_PP_LIMIT_TUPLE</a></li> | |
| 46 | </ul> | |
| 47 | <h4>Requirements</h4> | |
| 48 | <div> | |
| 49 | <b>Header:</b> <a href="../headers/tuple/elem.html"><boost/preprocessor/tuple/elem.hpp></a> | |
| 50 | </div> | |
| 51 | <h4>Sample Code</h4> | |
| 52 | <div><pre>#include <<a href="../headers/tuple/elem.html">boost/preprocessor/tuple/elem.hpp</a>><br><br>#define TUPLE (a, b, c, d)<br><br><a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 0, TUPLE) // expands to a<br><a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 3, TUPLE) // expands to d<br><br>// or for the variadic version <a href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a><br><br><a href="file:///C:/Programming/VersionControl/sandbox/variadics/libs/preprocessor/doc/ref/tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(0, TUPLE) // expands to a in the variadic version<br><a href="file:///C:/Programming/VersionControl/sandbox/variadics/libs/preprocessor/doc/ref/tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(3, TUPLE) // expands to d in the variadic version<br></pre></div> | |
| 53 | <hr size="1"> | |
| 54 | <div style="margin-left: 0px;"> | |
| 55 |