2002-10-03 22:13:37 +00:00
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<html>
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<head>
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<title>BOOST_PP_EMPTY</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_EMPTY</b> macro is a nullary utility macro that expands to nothing.
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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_EMPTY</b>()
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</div>
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<h4>Remarks</h4>
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<div>
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This macro is helps avoid inefficient macro-expansion.
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It is primarily useful as arguments to <b>BOOST_PP_IF</b> or <b>BOOST_PP_IIF</b>.
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</div>
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<h4>Requirements</h4>
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<div>
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2004-10-11 06:58:45 +00:00
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<b>Header:</b> <a href="../headers/facilities/empty.html"><boost/preprocessor/facilities/empty.hpp></a>
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2002-10-03 22:13:37 +00:00
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</div>
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<h4>Sample Code</h4>
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<div><pre>
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2004-10-11 06:58:45 +00:00
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#include <<a href="../headers/control/if.html">boost/preprocessor/control/if.hpp</a>>
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#include <<a href="../headers/facilities/empty.html">boost/preprocessor/facilities/empty.hpp</a>>
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2002-10-03 22:13:37 +00:00
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#define X() result
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#define MACRO(c) <a href="if.html">BOOST_PP_IF</a>(c, 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 result
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</pre></div>
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</body>
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</html>
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