projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | <?xml version="1.0" encoding="utf-8" ?> |
| 2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> | |
| 3 | <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> | |
| 4 | <head> | |
| 5 | <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> | |
| 6 | <meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> | |
| 7 | <title>The MPL Reference Manual: Trivial Metafunction</title> | |
| 8 | <link rel="stylesheet" href="../style.css" type="text/css" /> | |
| 9 | </head> | |
| 10 | <body class="docframe refmanual"> | |
| 11 | <table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./numeric-metafunction.html" class="navigation-link">Prev</a> <a href="./type-selection.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./numeric-metafunction.html" class="navigation-link">Back</a> Along</span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./metafunctions-concepts.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> | |
| 12 | <td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./metafunctions.html" class="navigation-link">Metafunctions</a> / <a href="./metafunctions-concepts.html" class="navigation-link">Concepts</a> / <a href="./trivial-metafunction.html" class="navigation-link">Trivial Metafunction</a></td> | |
| 13 | </tr></table><div class="header-separator"></div> | |
| 14 | <div class="section" id="trivial-metafunction"> | |
| 15 | <h1><a class="toc-backref" href="./metafunctions-concepts.html#id1518">Trivial Metafunction</a></h1> | |
| 16 | <div class="section" id="id853"> | |
| 17 | <h3><a class="subsection-title" href="#description" name="description">Description</a></h3> | |
| 18 | <p>A <a class="reference internal" href="./trivial-metafunction.html">Trivial Metafunction</a> accepts a single argument of a class type <tt class="literal"><span class="pre">x</span></tt> and | |
| 19 | returns the <tt class="literal"><span class="pre">x</span></tt>'s nested type member <tt class="literal"><span class="pre">x::name</span></tt>, where <tt class="literal"><span class="pre">name</span></tt> is | |
| 20 | a placeholder token for the actual member's name accessed by a specific | |
| 21 | metafunction's instance. By convention, all <a class="reference internal" href="./trivial-metafunctions-summary.html">trivial metafunctions</a> in MPL | |
| 22 | are named after the members they provide assess to. For instance, a <a class="reference internal" href="./trivial-metafunction.html">Trivial Metafunction</a> named <tt class="literal"><span class="pre">first</span></tt> reaches for the <tt class="literal"><span class="pre">x</span></tt>'s nested member | |
| 23 | <tt class="literal"><span class="pre">::first</span></tt>.</p> | |
| 24 | </div> | |
| 25 | <div class="section" id="id855"> | |
| 26 | <h3><a class="subsection-title" href="#expression-requirements" name="expression-requirements">Expression requirements</a></h3> | |
| 27 | <p>In the following table and subsequent specifications, <tt class="literal"><span class="pre">name</span></tt> is placeholder token for the names of | |
| 28 | the <a class="reference internal" href="./trivial-metafunction.html">Trivial Metafunction</a> itself and the accessed member, and <tt class="literal"><span class="pre">x</span></tt> is | |
| 29 | a class type such that <tt class="literal"><span class="pre">x::name</span></tt> is a valid <em>type-name</em>.</p> | |
| 30 | <table border="1" class="docutils table"> | |
| 31 | <colgroup> | |
| 32 | <col width="37%" /> | |
| 33 | <col width="26%" /> | |
| 34 | <col width="37%" /> | |
| 35 | </colgroup> | |
| 36 | <thead valign="bottom"> | |
| 37 | <tr><th class="head">Expression</th> | |
| 38 | <th class="head">Type</th> | |
| 39 | <th class="head">Complexity</th> | |
| 40 | </tr> | |
| 41 | </thead> | |
| 42 | <tbody valign="top"> | |
| 43 | <tr><td><tt class="literal"><span class="pre">name<x>::type</span></tt></td> | |
| 44 | <td>Any type</td> | |
| 45 | <td>Constant time.</td> | |
| 46 | </tr> | |
| 47 | </tbody> | |
| 48 | </table> | |
| 49 | </div> | |
| 50 | <div class="section" id="id856"> | |
| 51 | <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> | |
| 52 | <pre class="literal-block"> | |
| 53 | typedef name<x>::type r; | |
| 54 | </pre> | |
| 55 | <table class="docutils field-list" frame="void" rules="none"> | |
| 56 | <col class="field-name" /> | |
| 57 | <col class="field-body" /> | |
| 58 | <tbody valign="top"> | |
| 59 | <tr class="field"><th class="field-name">Precondition:</th><td class="field-body"><tt class="literal"><span class="pre">x::name</span></tt> is a valid <em>type-name</em>.</td> | |
| 60 | </tr> | |
| 61 | <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><tt class="literal"><span class="pre">is_same<r,x::name>::value</span> <span class="pre">==</span> <span class="pre">true</span></tt>.</td> | |
| 62 | </tr> | |
| 63 | </tbody> | |
| 64 | </table> | |
| 65 | </div> | |
| 66 | <div class="section" id="id857"> | |
| 67 | <h3><a class="subsection-title" href="#models" name="models">Models</a></h3> | |
| 68 | <ul class="simple"> | |
| 69 | <li><a class="reference internal" href="./trivial-metafunctions-summary.html#first">first</a></li> | |
| 70 | <li><a class="reference internal" href="./trivial-metafunctions-summary.html#second">second</a></li> | |
| 71 | <li><a class="reference internal" href="./trivial-metafunctions-summary.html#base">base</a></li> | |
| 72 | </ul> | |
| 73 | </div> | |
| 74 | <div class="section" id="id858"> | |
| 75 | <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> | |
| 76 | <p><a class="reference internal" href="./metafunctions.html">Metafunctions</a>, <a class="reference internal" href="./trivial.html#label-metafunctions-trivial">Trivial Metafunctions</a>, <a class="reference internal" href="./identity.html">identity</a></p> | |
| 77 | </div> | |
| 78 | </div> | |
| 79 | ||
| 80 | <div class="footer-separator"></div> | |
| 81 | <table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./numeric-metafunction.html" class="navigation-link">Prev</a> <a href="./type-selection.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./numeric-metafunction.html" class="navigation-link">Back</a> Along</span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./metafunctions-concepts.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> | |
| 82 | <td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> | |
| 83 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
| 84 | file LICENSE_1_0.txt or copy at <a class="reference external" href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</div></td></tr></table></body> | |
| 85 | </html> |