preprocessor/doc/ref/repeat_z.html

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<title>BOOST_PP_REPEAT_z</title>
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<div style="margin-left: 0px;"> The <b>BOOST_PP_REPEAT_<i>z</i></b> macro
represents a reentry into the <b>BOOST_PP_REPEAT</b> repetition
construct. </div>
<h4>Usage</h4>
<div class="code"> <b>BOOST_PP_REPEAT_</b> ## <i>z</i>(<i>count</i>, <i>macro</i>,
<i>data</i>) </div>
<h4>Arguments</h4>
<dl>
<dt>z</dt>
<dd> The next available <b>BOOST_PP_REPEAT</b> dimension. </dd>
<dt>count</dt>
<dd> The number of repetitious calls to <i>macro</i>.&nbsp; Valid values
range from <i>0</i> to <b>BOOST_PP_LIMIT_REPEAT</b>. </dd>
<dt>macro</dt>
<dd> A ternary operation of the form <i>macro</i>(<i>z</i>, <i>n</i>, <i>data</i>).&nbsp;
This macro is expanded by <b>BOOST_PP_REPEAT</b> with the next
available repetition depth, the current repetition number, and the
auxiliary <i>data</i> argument.&nbsp; </dd>
<dt>data</dt>
<dd> Auxiliary data passed to <i>macro</i>. </dd>
</dl>
<h4>Remarks</h4>
<div> This macro expands to the sequence:
<div> <i>macro</i>(<i>z</i>, <i>0</i>, <i>data</i>) <i>macro</i>(<i>z</i>,
<i>1</i>, <i>data</i>) ... <i>macro</i>(<i>z</i>, <i>count</i> - <i>1</i>,
<i>data</i>) </div>
</div>
<div> At certain times, it may be necessary to perform the concatenation
with <b>BOOST_PP_CAT</b> rather than the preprocessor token-pasting
operator.&nbsp; This happens when the <i>z</i> value is a macro
invocation itself.&nbsp; It needs a delay to allow it to expand.&nbsp; The
syntax in such a scenario becomes:
<div> <b>BOOST_PP_CAT</b>(<b>BOOST_PP_REPEAT_</b>, <i>z</i>)(<i>count</i>,
<i>macro</i>, <i>data</i>) </div>
</div>
<h4>See Also</h4>
<ul>
<li><a href="cat.html">BOOST_PP_CAT</a></li>
<li><a href="limit_repeat.html">BOOST_PP_LIMIT_REPEAT</a></li>
<li><a href="repeat.html">BOOST_PP_REPEAT</a></li>
<li><a href="repeat_z_macros.html"><span style="color: gray;">Macros with
Z re-entrancy forms</span></a></li>
</ul>
<h4>Requirements</h4>
<div> <b>Header:</b> &nbsp;<a href="../headers/repetition/repeat.html">&lt;boost/preprocessor/repetition/repeat.hpp&gt;</a>
</div>
<h4>Sample Code</h4>
<div>
<pre>#include &lt;<a href="../headers/arithmetic/inc.html">boost/preprocessor/arithmetic/inc.hpp</a>&gt;
#include &lt;<a href="../headers/punctuation/comma_if.html">boost/preprocessor/punctuation/comma_if.hpp</a>&gt;
#include &lt;<a href="../headers/repetition/repeat.html">boost/preprocessor/repetition/repeat.hpp</a>&gt;
#define TEXT(z, n, text) <a href="comma_if.html">BOOST_PP_COMMA_IF</a>(n) text
#define TEMPLATE(z, n, _) \
<a href="comma_if.html">BOOST_PP_COMMA_IF</a>(n) \
template&lt; \
<a href="repeat_z.html">BOOST_PP_REPEAT_</a> ## z( \
<a href="inc.html">BOOST_PP_INC</a>(n), \
TEXT, class \
) \
&gt; class T ## n \
/**/
<a href="repeat.html">BOOST_PP_REPEAT</a>(3, TEMPLATE, nil)
/*
expands to:
template&lt;class&gt; class T0,
template&lt;class, class&gt; class T1,
template&lt;class, class, class&gt; class T2
*/
</pre></div>
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<div style="margin-left: 0px;"> <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 2014</i><br>
</div>
<div style="margin-left: 0px;">
<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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