<?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> <title>The MPL Reference Manual: inherit</title> <link rel="stylesheet" href="../style.css" type="text/css" /> </head> <body class="docframe refmanual"> <table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./always.html" class="navigation-link">Prev</a> <a href="./inherit-linearly.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./always.html" class="navigation-link">Back</a> <a href="./inherit-linearly.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./miscellaneous.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> <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="./miscellaneous.html" class="navigation-link">Miscellaneous</a> / <a href="./inherit.html" class="navigation-link">inherit</a></td> </tr></table><div class="header-separator"></div> <div class="section" id="inherit"> <h1><a class="toc-backref" href="./miscellaneous.html#id1566">inherit</a></h1> <div class="section" id="id1163"> <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> <pre class="literal-block"> template< typename T1, typename T2 > struct <a href="./inherit.html" class="identifier">inherit</a><tt class="literal"><span class="pre">2</span></tt> { typedef <em>unspecified</em> type; }; <em>...</em> template< typename T1, typename T2,<em>...</em> typename T<em>n</em> > struct <a href="./inherit.html" class="identifier">inherit</a><em>n</em> { typedef <em>unspecified</em> type; }; template< typename T1 , typename T2 <em>...</em> , typename T<em>n</em> = <em>unspecified</em> > struct <a href="./inherit.html" class="identifier">inherit</a> { typedef <em>unspecified</em> type; }; </pre> </div> <div class="section" id="id1164"> <h3><a class="subsection-title" href="#description" name="description">Description</a></h3> <p>Returns an unspecified class type publically derived from <tt class="literal"><span class="pre">T1</span></tt>, <tt class="literal"><span class="pre">T2</span></tt>,... <tt class="literal"><span class="pre">Tn</span></tt>. Guarantees that derivation from <a class="reference internal" href="./empty-base.html">empty_base</a> is always a no-op, regardless of the position and number of <a class="reference internal" href="./empty-base.html">empty_base</a> classes in <tt class="literal"><span class="pre">T1</span></tt>, <tt class="literal"><span class="pre">T2</span></tt>,... <tt class="literal"><span class="pre">Tn</span></tt>.</p> </div> <div class="section" id="id1165"> <h3><a class="subsection-title" href="#header" name="header">Header</a></h3> <pre class="literal-block"> #include <<a href="../../../../boost/mpl/inherit.hpp" class="header">boost/mpl/inherit.hpp</a>> </pre> </div> <div class="section" id="id1166"> <h3><a class="subsection-title" href="#model-of" name="model-of">Model of</a></h3> <p><a class="reference internal" href="./metafunction.html">Metafunction</a></p> </div> <div class="section" id="id1167"> <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3> <table border="1" class="docutils table"> <colgroup> <col width="22%" /> <col width="28%" /> <col width="51%" /> </colgroup> <thead valign="bottom"> <tr><th class="head">Parameter</th> <th class="head">Requirement</th> <th class="head">Description</th> </tr> </thead> <tbody valign="top"> <tr><td><tt class="literal"><span class="pre">T1</span></tt>, <tt class="literal"><span class="pre">T2</span></tt>,... <tt class="literal"><span class="pre">Tn</span></tt></td> <td>A class type</td> <td>Classes to derived from.</td> </tr> </tbody> </table> </div> <div class="section" id="id1168"> <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> <p>For artibrary class types <em>t</em><sub>1</sub>,<em>t</em><sub>2</sub>,... <em>t</em><sub>n</sub>:</p> <pre class="literal-block"> typedef inherit2<t1,t2>::type r; </pre> <table class="docutils field-list" frame="void" rules="none"> <col class="field-name" /> <col class="field-body" /> <tbody valign="top"> <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">A class type.</p> </td> </tr> <tr class="field"><th class="field-name">Precondition:</th><td class="field-body"><p class="first"><tt class="literal"><span class="pre">t1</span></tt> and <tt class="literal"><span class="pre">t2</span></tt> are complete types.</p> </td> </tr> <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">If both <tt class="literal"><span class="pre">t1</span></tt> and <tt class="literal"><span class="pre">t2</span></tt> are identical to <tt class="literal"><span class="pre"><a href="./empty-base.html" class="identifier">empty_base</a></span></tt>, equivalent to</p> <pre class="literal-block"> typedef <a href="./empty-base.html" class="identifier">empty_base</a> r; </pre> <p>otherwise, if <tt class="literal"><span class="pre">t1</span></tt> is identical to <tt class="literal"><span class="pre"><a href="./empty-base.html" class="identifier">empty_base</a></span></tt>, equivalent to</p> <pre class="literal-block"> typedef t2 r; </pre> <p>otherwise, if <tt class="literal"><span class="pre">t2</span></tt> is identical to <tt class="literal"><span class="pre"><a href="./empty-base.html" class="identifier">empty_base</a></span></tt>, equivalent to</p> <pre class="literal-block"> typedef t1 r; </pre> <p>otherwise equivalent to</p> <pre class="last literal-block"> struct r : t1, t2 {}; </pre> </td> </tr> </tbody> </table> <!-- ........................................................................... --> <pre class="literal-block"> typedef <a href="./inherit.html" class="identifier">inherit</a><em>n</em><t1,t2,<em>...</em>t<em>n</em>>::type r; </pre> <table class="docutils field-list" frame="void" rules="none"> <col class="field-name" /> <col class="field-body" /> <tbody valign="top"> <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">A class type.</p> </td> </tr> <tr class="field"><th class="field-name">Precondition:</th><td class="field-body"><p class="first"><em>t</em><sub>1</sub>,<em>t</em><sub>2</sub>,... <em>t</em><sub>n</sub> are complete types.</p> </td> </tr> <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p> <pre class="last literal-block"> struct r : <a href="./inherit.html" class="identifier">inherit</a><tt class="literal"><span class="pre">2</span></tt>< <a href="./inherit.html" class="identifier">inherit</a><em>n-1</em><t1,t2,<em>...</em>t<em>n-1</em>>::type , t<em>n</em> > { }; </pre> </td> </tr> </tbody> </table> <!-- ........................................................................... --> <pre class="literal-block"> typedef <a href="./inherit.html" class="identifier">inherit</a><t1,t2,<em>...</em>t<em>n</em>>::type r; </pre> <table class="docutils field-list" frame="void" rules="none"> <col class="field-name" /> <col class="field-body" /> <tbody valign="top"> <tr class="field"><th class="field-name">Precondition:</th><td class="field-body"><p class="first"><em>t</em><sub>1</sub>,<em>t</em><sub>2</sub>,... <em>t</em><sub>n</sub> are complete types.</p> </td> </tr> <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">A class type.</p> </td> </tr> <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p> <pre class="last literal-block"> typedef <a href="./inherit.html" class="identifier">inherit</a><em>n</em><t1,t2,<em>...</em>t<em>n</em>>::type r; </pre> </td> </tr> </tbody> </table> </div> <div class="section" id="id1169"> <h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3> <p>Amortized constant time.</p> </div> <div class="section" id="id1170"> <h3><a class="subsection-title" href="#example" name="example">Example</a></h3> <pre class="literal-block"> struct udt1 { int n; }; struct udt2 {}; typedef <a href="./inherit.html" class="identifier">inherit</a><udt1,udt2>::type r1; typedef <a href="./inherit.html" class="identifier">inherit</a><<a href="./empty-base.html" class="identifier">empty_base</a>,udt1>::type r2; typedef <a href="./inherit.html" class="identifier">inherit</a><<a href="./empty-base.html" class="identifier">empty_base</a>,udt1,<a href="./empty-base.html" class="identifier">empty_base</a>,<a href="./empty-base.html" class="identifier">empty_base</a>>::type r3; typedef <a href="./inherit.html" class="identifier">inherit</a><udt1,<a href="./empty-base.html" class="identifier">empty_base</a>,udt2>::type r4; typedef <a href="./inherit.html" class="identifier">inherit</a><<a href="./empty-base.html" class="identifier">empty_base</a>,<a href="./empty-base.html" class="identifier">empty_base</a>>::type r5; <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_base_and_derived< udt1, r1> )); <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_base_and_derived< udt2, r1> )); <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same< r2, udt1> )); <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same< r3, udt1 > )); <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_base_and_derived< udt1, r4 > )); <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_base_and_derived< udt2, r4 > )); <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same< r5, <a href="./empty-base.html" class="identifier">empty_base</a> > )); </pre> </div> <div class="section" id="id1171"> <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> <p><a class="reference internal" href="./metafunctions.html">Metafunctions</a>, <a class="reference internal" href="./empty-base.html">empty_base</a>, <a class="reference internal" href="./inherit-linearly.html">inherit_linearly</a>, <a class="reference internal" href="./identity.html">identity</a></p> <!-- Metafunctions/Miscellaneous//inherit_linearly |40 --> </div> </div> <div class="footer-separator"></div> <table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./always.html" class="navigation-link">Prev</a> <a href="./inherit-linearly.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./always.html" class="navigation-link">Back</a> <a href="./inherit-linearly.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./miscellaneous.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> <td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> Distributed under the Boost Software License, Version 1.0. 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