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1 | <html> |
2 | <head> | |
3 | <title>BOOST_PP_ENUM_TRAILING_z</title> | |
4 | <link rel="stylesheet" type="text/css" href="../styles.css"> | |
5 | </head> | |
6 | <body> | |
7 | <div style="margin-left: 0px;"> | |
8 | The <b>BOOST_PP_ENUM_TRAILING_<i>z</i></b> macro represents a reentry into the <b>BOOST_PP_ENUM_TRAILING</b> repetition construct. | |
9 | </div> | |
10 | <h4>Usage</h4> | |
11 | <div class="code"> | |
12 | <b>BOOST_PP_ENUM_TRAILING_</b> ## <i>z</i>(<i>count</i>, <i>macro</i>, <i>data</i>) | |
13 | </div> | |
14 | <h4>Arguments</h4> | |
15 | <dl> | |
16 | <dt>z</dt> | |
17 | <dd> | |
18 | The next available <b>BOOST_PP_REPEAT</b> dimension. | |
19 | </dd> | |
20 | <dt>count</dt> | |
21 | <dd> | |
22 | The number of repetitious calls to <i>macro</i>. | |
23 | Valid values range from <i>0</i> to <b>BOOST_PP_LIMIT_REPEAT</b>. | |
24 | </dd> | |
25 | <dt>macro</dt> | |
26 | <dd> | |
27 | A ternary operation of the form <i>macro</i>(<i>z</i>, <i>n</i>, <i>data</i>). | |
28 | This macro is expanded by <b>BOOST_PP_ENUM</b> with the next available repetition depth, | |
29 | the current repetition number, and the auxiliary <i>data</i> argument. | |
30 | </dd> | |
31 | <dt>data</dt> | |
32 | <dd> | |
33 | Auxiliary data passed to <i>macro</i>. | |
34 | </dd> | |
35 | </dl> | |
36 | <h4>Remarks</h4> | |
37 | <div> | |
38 | This macro expands to the sequence: | |
39 | <div> | |
40 | , <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>) | |
41 | </div> | |
42 | </div> | |
43 | <div> | |
44 | At certain times, it may be necessary to perform the concatenation with <b>BOOST_PP_CAT</b> rather than the preprocessor token-pasting operator. | |
45 | This happens when the <i>z</i> value is a macro invocation itself. | |
46 | It needs a delay to allow it to expand. | |
47 | The syntax in such a scenario becomes: | |
48 | <div> | |
49 | <b>BOOST_PP_CAT</b>(<b>BOOST_PP_ENUM_TRAILING_</b>, <i>z</i>)(<i>count</i>, <i>macro</i>, <i>data</i>) | |
50 | </div> | |
51 | </div> | |
52 | <h4>See Also</h4> | |
53 | <ul> | |
54 | <li><a href="cat.html">BOOST_PP_CAT</a></li> | |
55 | <li><a href="enum_trailing.html">BOOST_PP_ENUM_TRAILING</a></li> | |
56 | <li><a href="limit_repeat.html">BOOST_PP_LIMIT_REPEAT</a></li> | |
57 | </ul> | |
58 | <h4>Requirements</h4> | |
59 | <div> | |
60 | <b>Header:</b> <a href="../headers/repetition/enum_trailing.html"><boost/preprocessor/repetition/enum_trailing.hpp></a> | |
61 | </div> | |
62 | <h4>Sample Code</h4> | |
63 | <div><pre> | |
64 | #include <<a href="../headers/repetition/enum.html">boost/preprocessor/repetition/enum.hpp</a>> | |
65 | #include <<a href="../headers/repetition/enum_trailing.html">boost/preprocessor/repetition/enum_trailing.hpp</a>> | |
66 | ||
67 | #define TEXT(z, n, text) text | |
68 | ||
69 | #define TTP(z, n, _) \ | |
70 | template< \ | |
71 | class <a href="enum_z.html">BOOST_PP_ENUM_TRAILING_</a> ## z(n, TEXT, class) \ | |
72 | > \ | |
73 | class T ## n \ | |
74 | /**/ | |
75 | ||
76 | <a href="enum.html">BOOST_PP_ENUM</a>(3, TTP, nil) | |
77 | /* | |
78 | expands to... | |
79 | template<class> class T0, | |
80 | template<class, class> class T1, | |
81 | template<class, class, class> class T2 | |
82 | */ | |
83 | </pre></div> | |
84 | <hr size="1"> | |
85 | <div style="margin-left: 0px;"> | |
86 |