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| 1 | <html> |
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| 2 | <head> |
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| 3 | <title>BOOST_PP_APPLY</title> |
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| 4 | <link rel="stylesheet" type="text/css" href="../styles.css"> |
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| 5 | </head> |
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| 6 | <body> |
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| 7 | <div style="margin-left: 0px;"> |
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| 8 | The <b>BOOST_PP_APPLY</b> macro abstracts the difference between an argument and nothing. |
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| 9 | </div> |
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| 10 | <h4>Usage</h4> |
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| 11 | <div class="code"> |
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| 12 | <b>BOOST_PP_APPLY</b>(<i>x</i>) |
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| 13 | </div> |
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| 14 | <h4>Arguments</h4> |
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| 15 | <dl> |
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| 16 | <dt>x</dt> |
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| 17 | <dd> |
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| 18 | The abstracted argument. |
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| 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>. |
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| 20 | </dd> |
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| 21 | </dl> |
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| 22 | <h4>Remarks</h4> |
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| 23 | <div> |
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| 24 | If <i>x</i> is <b>BOOST_PP_NIL</b>, this macro expands to nothing. |
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| 25 | If <i>x</i> is a one element <i>tuple</i>, it expands to the contents of that <i>tuple</i>. |
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| 26 | </div> |
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| 27 | <h4>See Also</h4> |
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| 28 | <ul> |
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| 29 | <li><a href="nil.html">BOOST_PP_NIL</a></li> |
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| 30 | </ul> |
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| 31 | <h4>Requirements</h4> |
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| 32 | <div> |
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| 33 | <b>Header:</b> <a href="../headers/facilities/apply.html"><boost/preprocessor/facilities/apply.hpp></a> |
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| 34 | </div> |
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| 35 | <h4>Sample Code</h4> |
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| 36 | <div><pre> |
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| 37 | #include <<a href="../headers/facilities/apply.html">boost/preprocessor/facilities/apply.hpp</a>> |
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| 38 | #include <<a href="../headers/tuple/elem.html">boost/preprocessor/tuple/elem.hpp</a>> |
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| 39 | |
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| 40 | #define CV(i) \ |
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| 41 | <a href="apply.html">BOOST_PP_APPLY</a>( \ |
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| 42 | <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>( \ |
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| 43 | 4, i, \ |
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| 44 | (<a href="nil.html">BOOST_PP_NIL</a>, (const), (volatile), (const volatile)) \ |
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| 45 | ) \ |
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| 46 | ) \ |
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| 47 | /**/ |
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| 48 | |
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| 49 | CV(0) // expands to nothing |
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| 50 | CV(1) // expands to const |
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| 51 | </pre></div> |
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| 52 | </body> |
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| 53 | </html> |
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