forked from boostorg/preprocessor
46 lines
2.7 KiB
HTML
46 lines
2.7 KiB
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<html>
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<head>
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<title>BOOST_PP_OVERLOAD</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;"> The <b>BOOST_PP_OVERLOAD</b> variadic macro expands to the name of a non-variadic macro having a given number of parameters.<br>
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</div>
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<h4>Usage</h4>
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<div class="code"> <b>BOOST_PP_OVERLOAD</b>(<i>prefix</i>,...) <sup>(v)</sup><br>
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</div>
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<h4>Arguments</h4>
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<dl>
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<dt>prefix<br>
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</dt><dd>
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The prefix of the non-variadic macro name.
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</dd><dt>...<br>
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</dt><dd><i>
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Variadic data</i>. The number of variadic data
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elements, as determined by BOOST_PP_VARIADIC_SIZE, is appended to the
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prefix to form the output non-variadic macro name.<br>
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</dd>
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</dl>
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<h4>Remarks</h4>
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<div> This macro creates a macro name which depends on the number of elements of variadic data. It should be used in the form of <br>
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BOOST_PP_OVERLOAD(MACRO_NAME_,__VA_ARGS__)(__VA_ARGS__) in order to
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call a non-variadic macro taking a given number of variadic data
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elements as non-variadic arguments. In this way one can invoke a
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variadic macro with a variable number of parameters which calls one of
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a series of non-variadic macros doing very similar things.
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</div><b>Requirements</b>
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<div> <b>Header:</b> <a href="../headers/facilities/overload.html"><boost/preprocessor/facilities/overload.hpp></a>
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</div>
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<h4>Sample Code</h4>
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<div>
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<pre>#include <<a href="../headers/facilities/overload.html">boost/preprocessor/facilities/overload.hpp</a>><br>#include <<a href="../headers/cat.html">boost/preprocessor/cat.hpp</a>><br>#include <<a href="../headers/facilities/empty.html">boost/preprocessor/facilities/empty.hpp</a>><br>#include <<a href="../headers/arithmetic/add.html">boost/preprocessor/arithmetic/add.hpp</a>><br><br>#define MACRO_1(number) MACRO_2(number,10)<br>#define MACRO_2(number1,number2) <a href="add.html">BOOST_PP_ADD</a>(number1,number2)<br><br>#define MACRO_ADD_NUMBERS(...) <a href="overload.html">BOOST_PP_OVERLOAD</a>(MACRO_,__VA_ARGS__)(__VA_ARGS__)<br><br>// or for Visual C++<br><br>#define MACRO_ADD_NUMBERS(...) \<br> <a href="cat.html">BOOST_PP_CAT</a>(<a href="overload.html">BOOST_PP_OVERLOAD</a>(MACRO_,__VA_ARGS__)(__VA_ARGS__),<a href="empty.html">BOOST_PP_EMPTY</a>())<br><br>MACRO_ADD_NUMBERS(5) // output is 15<br>MACRO_ADD_NUMBERS(3,6) // output is 9<br></pre>
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</div>
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<hr size="1">
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<div style="margin-left: 0px;"> <i></i><i><EFBFBD> Copyright Edward Diener 2011</i> </div>
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<div style="margin-left: 0px;">
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<p><small>Distributed under the Boost Software License, Version 1.0.
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(See accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a>
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or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
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</div>
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</body>
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</html>
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