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lib cleanup

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[SVN r15693]
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Paul Mensonides
2002-10-03 22:13:37 +00:00
parent ae584c68b2
commit 4bb690a819
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<html>
<head>
<title>BOOST_PP_DEDUCE_D</title>
<link rel="stylesheet" type="text/css" href="../styles.css">
</head>
<body>
<div style="margin-left: 0px;">
The <b>BOOST_PP_DEDUCE_D</b> macro manually deduces the state of the <b>BOOST_PP_WHILE</b> construct.
</div>
<h4>Usage</h4>
<div class="code">
<b>BOOST_PP_DEDUCE_D</b>()
</div>
<h4>Remarks</h4>
<div>
This macro is intended to avoid the use of <i>automatic-recursion</i> at deep expansion depths.&nbsp;
<i>Automatic-recursion</i> at such depths can be inefficient on some preprocessors.&nbsp;
It is not intended to be used directly with the invocation of macros with a <b>_D</b> suffix such as:
<div>
<b>BOOST_PP_ADD_D</b>(<b>BOOST_PP_DEDUCE_D</b>(), <i>x</i>, <i>y</i>)
</div>
If it is used in this context, the <b>_D</b> macro will fail.&nbsp;
The <b>_D</b> macros directly concatenate to the <i>d</i> parameter that is passed to them,
which would prevent <b>BOOST_PP_DEDUCE_D</b>() from expanding.&nbsp;
Furthermore, it is pointless to use this macro in a situation such as this
because it would already be too late to gain any efficiency.
</div>
<h4>See Also</h4>
<ul>
<li><a href="while.html">BOOST_PP_WHILE</a></li>
</ul>
<h4>Requirements</h4>
<div>
<b>Header:</b> &nbsp;<a href="../headers/control/deduce_d.hpp.html">&lt;boost/preprocessor/control/deduce_d.hpp&gt;</a>
</div>
<h4>Sample Code</h4>
<div><pre>
#include &lt;<a href="../headers/arithmetic/add.hpp.html">boost/preprocessor/arithmetic/add.hpp</a>&gt;
#include &lt;<a href="../headers/arithmetic/inc.hpp.html">boost/preprocessor/arithmetic/inc.hpp</a>&gt;
#include &lt;<a href="../headers/arithmetic/sub.hpp.html">boost/preprocessor/arithmetic/sub.hpp</a>&gt;
#include &lt;<a href="../headers/control/deduce_d.hpp.html">boost/preprocessor/control/deduce_d.hpp</a>&gt;
#include &lt;<a href="../headers/punctuation/comma_if.hpp.html">boost/preprocessor/punctuation/comma_if.hpp</a>&gt;
#include &lt;<a href="../headers/repetition/repeat.hpp.html">boost/preprocessor/repetition/repeat.hpp</a>&gt;
#include &lt;<a href="../headers/tuple/elem.hpp.html">boost/preprocessor/tuple/elem.hpp</a>&gt;
#define RANGE(first, last) \
<a href="repeat.html">BOOST_PP_REPEAT</a>( \
<a href="inc.html">BOOST_PP_INC</a>( \
<a href="sub.html">BOOST_PP_SUB</a>(last, first) \
, \
RANGE_M, \
(first, <a href="deduce_d.html">BOOST_PP_DEDUCE_D</a>()) \
) \
/**/
#define RANGE_M(z, n, data) \
RANGE_M_2( \
n, \
<a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(2, 0, data), \
<a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(2, 1, data) \
) \
/**/
#define RANGE_M_2(n, first, d) \
<a href="comma_if.html">BOOST_PP_COMMA_IF</a>(n) <a href="add_d.html">BOOST_PP_ADD_D</a>(d, n, first) \
/**/
RANGE(5, 10) // expands to 5, 6, 7, 8, 9, 10
</pre></div>
</body>
</html>