preprocessor/doc/ref/tuple_eat.html
2018-01-11 14:20:16 +00:00

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<title>BOOST_PP_TUPLE_EAT</title>
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The <b>BOOST_PP_TUPLE_EAT</b> macro expands to a macro that eats a <i>tuple</i>.
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<h4>Usage</h4>
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<b>BOOST_PP_TUPLE_EAT</b>(<i>size</i>)<br>
<br>
or<br>
<br>
<b>BOOST_PP_TUPLE_EAT</b>(<i>size</i>) <a href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a><b></b><br>
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<h4>Arguments</h4>
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<dt>size</dt>
<dd>
The size of the <i>tuple</i> to be eaten.&nbsp;
Valid <i>tuple</i> sizes range from <i>1</i> to <b>BOOST_PP_LIMIT_TUPLE</b>.
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<h4>Remarks</h4>
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The <i>size</i> argument must be the actual size of the <i>tuple</i> in the non-variadic version. <br>
<br>For the variadic version <a href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a>&nbsp;the
size may be left out
completely so that the macro can be invoked as BOOST_PP_TUPLE_EAT(); you may get a warning from some compilers, but the
functionality will still work. If you specify a size in the variadic
version, it will be ignored, but the warning from some compilers will
not occur.<br>
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<h4>See Also</h4>
<ul>
<li><a href="limit_tuple.html">BOOST_PP_LIMIT_TUPLE</a></li>
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<h4>Requirements</h4>
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<b>Header:</b> &nbsp;<a href="../headers/tuple/eat.html">&lt;boost/preprocessor/tuple/eat.hpp&gt;</a>
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<h4>Sample Code</h4>
<div><pre>#include &lt;<a href="../headers/control/if.html">boost/preprocessor/control/if.hpp</a>&gt;<br>#include &lt;<a href="../headers/tuple/eat.html">boost/preprocessor/tuple/eat.hpp</a>&gt;<br><br>#define OP(a, b) (a b)<br><br>#define MACRO(n) <a href="if.html">BOOST_PP_IF</a>(n, OP, <a href="tuple_eat.html">BOOST_PP_TUPLE_EAT</a>(2))(1, 2)<br><br>// or for the variadic version <a href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a><br><br>#define MACRO(n) <a href="if.html">BOOST_PP_IF</a>(n, OP, <a href="tuple_eat.html">BOOST_PP_TUPLE_EAT</a>())(1, 2)<br><br>MACRO(0) // expands to nothing<br>MACRO(1) // expands to (1, 2)<br></pre></div>
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<i><EFBFBD> Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i>
<br><i><EFBFBD> Copyright Paul Mensonides 2002<br>
</i><i><EFBFBD> Copyright Edward Diener 2011,2013</i><br>
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<p><small>Distributed under the Boost Software License, Version 1.0. (See
accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> 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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