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47 lines
1.5 KiB
HTML
47 lines
1.5 KiB
HTML
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<html>
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<head>
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<title>BOOST_PP_IDENTITY</title>
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<link rel="stylesheet" type="text/css" href="../styles.css">
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</head>
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<body>
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<div style="margin-left: 0px;">
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The <b>BOOST_PP_IDENTITY</b> macro expands to its argument when invoked.
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</div>
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<h4>Usage</h4>
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<div class="code">
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<b>BOOST_PP_IDENTITY</b>(<i>item</i>)()
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</div>
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<h4>Arguments</h4>
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<dl>
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<dt>item</dt>
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<dd>
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The result of the expansion.
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</dd>
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</dl>
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<h4>Remarks</h4>
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<div>
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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.
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</div>
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<h4>See Also</h4>
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<ul>
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<li><a href="if.html">BOOST_PP_IF</a></li>
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<li><a href="iif.html">BOOST_PP_IIF</a></li>
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</ul>
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<h4>Requirements</h4>
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<div>
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<b>Header:</b> <a href="../headers/facilities/identity.hpp.html"><boost/preprocessor/facilities/identity.hpp></a>
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</div>
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<h4>Sample Code</h4>
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<div><pre>
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#include <<a href="../headers/control/if.hpp.html">boost/preprocessor/control/if.hpp</a>>
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#include <<a href="../headers/facilities/empty.hpp.html">boost/preprocessor/facilities/empty.hpp</a>>
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#include <<a href="../headers/facilities/identity.hpp.html">boost/preprocessor/facilities/identity.hpp</a>>
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#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>)()
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MACRO(0) // expands to nothing
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MACRO(1) // expands to x
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</pre></div>
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</body>
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</html>
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