libs/preprocessor/doc/ref/apply.html


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64

<html>
<head>
	<title>BOOST_PP_APPLY</title>
	<link rel="stylesheet" type="text/css" href="../styles.css">
</head>
<body>
	<div style="margin-left:  0px;">
		The <b>BOOST_PP_APPLY</b> macro abstracts the difference between an argument and nothing.
	</div>
	<h4>Usage</h4>
		<div class="code">
			<b>BOOST_PP_APPLY</b>(<i>x</i>)
		</div>
	<h4>Arguments</h4>
		<dl>
			<dt>x</dt>
			<dd>
				The abstracted argument.&nbsp;
				This argument must be either <b>BOOST_PP_NIL</b> or a <i>tuple</i> with one element--such as <i>(arg)</i> or <i>((a, b))</i>.
			</dd>
		</dl>
	<h4>Remarks</h4>
		<div>
			If <i>x</i> is <b>BOOST_PP_NIL</b>, this macro expands to nothing.&nbsp;
			If <i>x</i> is a one element <i>tuple</i>, it expands to the contents of that <i>tuple</i>.
		</div>
	<h4>See Also</h4>
		<ul>
			<li><a href="nil.html">BOOST_PP_NIL</a></li>
		</ul>
	<h4>Requirements</h4>
		<div>
			<b>Header:</b> &nbsp;<a href="../headers/facilities/apply.html">&lt;boost/preprocessor/facilities/apply.hpp&gt;</a>
		</div>
	<h4>Sample Code</h4>
<div><pre>
#include &lt;<a href="../headers/facilities/apply.html">boost/preprocessor/facilities/apply.hpp</a>&gt;
#include &lt;<a href="../headers/tuple/elem.html">boost/preprocessor/tuple/elem.hpp</a>&gt;

#define CV(i) \
   <a href="apply.html">BOOST_PP_APPLY</a>( \
      <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>( \
         4, i, \
         (<a href="nil.html">BOOST_PP_NIL</a>, (const), (volatile), (const volatile)) \
      ) \
   ) \
   /**/

CV(0) // expands to nothing
CV(1) // expands to const
</pre></div>
	<hr size="1">
	<div style="margin-left: 0px;">
		<i>© Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i>
		</br><i>© Copyright Paul Mensonides 2002</i>
	</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>
	</div>
</body>
</html>