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: clear</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="./begin.html" class="navigation-link">Prev</a> <a href="./empty.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./begin.html" class="navigation-link">Back</a> <a href="./empty.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./intrinsic-metafunctions.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="./sequences.html" class="navigation-link">Sequences</a> / <a href="./intrinsic-metafunctions.html" class="navigation-link">Intrinsic Metafunctions</a> / <a href="./clear.html" class="navigation-link">clear</a></td> 13</tr></table><div class="header-separator"></div> 14<div class="section" id="clear"> 15<h1><a class="toc-backref" href="./intrinsic-metafunctions.html#id1429">clear</a></h1> 16<div class="section" id="id211"> 17<h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> 18<pre class="literal-block"> 19template< 20 typename Sequence 21 > 22struct <a href="./clear.html" class="identifier">clear</a> 23{ 24 typedef <em>unspecified</em> type; 25}; 26</pre> 27</div> 28<div class="section" id="id212"> 29<h3><a class="subsection-title" href="#description" name="description">Description</a></h3> 30<p>Returns an empty sequence <a class="reference internal" href="./terminology.html#concept-identical">concept-identical</a> to <tt class="literal"><span class="pre">Sequence</span></tt>.</p> 31</div> 32<div class="section" id="id213"> 33<h3><a class="subsection-title" href="#header" name="header">Header</a></h3> 34<pre class="literal-block"> 35#include <<a href="../../../../boost/mpl/clear.hpp" class="header">boost/mpl/clear.hpp</a>> 36</pre> 37</div> 38<div class="section" id="id214"> 39<h3><a class="subsection-title" href="#model-of" name="model-of">Model of</a></h3> 40<p><a class="reference internal" href="./tag-dispatched-metafunction.html">Tag Dispatched Metafunction</a></p> 41</div> 42<div class="section" id="id215"> 43<h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3> 44<table border="1" class="docutils table"> 45<colgroup> 46<col width="17%" /> 47<col width="39%" /> 48<col width="44%" /> 49</colgroup> 50<thead valign="bottom"> 51<tr><th class="head">Parameter</th> 52<th class="head">Requirement</th> 53<th class="head">Description</th> 54</tr> 55</thead> 56<tbody valign="top"> 57<tr><td><tt class="literal"><span class="pre">Sequence</span></tt></td> 58<td><a class="reference internal" href="./extensible-sequence.html">Extensible Sequence</a> or 59<a class="reference internal" href="./extensible-associative-sequence.html">Extensible Associative Sequence</a></td> 60<td>A sequence to get an empty "copy" of.</td> 61</tr> 62</tbody> 63</table> 64</div> 65<div class="section" id="id216"> 66<h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> 67<p>For any <a class="reference internal" href="./extensible-sequence.html">Extensible Sequence</a> or <a class="reference internal" href="./extensible-associative-sequence.html">Extensible Associative Sequence</a> <tt class="literal"><span class="pre">s</span></tt>:</p> 68<pre class="literal-block"> 69typedef <a href="./clear.html" class="identifier">clear</a><s>::type t; 70</pre> 71<table class="docutils field-list" frame="void" rules="none"> 72<col class="field-name" /> 73<col class="field-body" /> 74<tbody valign="top"> 75<tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first"><a class="reference internal" href="./extensible-sequence.html">Extensible Sequence</a> or <a class="reference internal" href="./extensible-associative-sequence.html">Extensible Associative Sequence</a>.</p> 76</td> 77</tr> 78<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p> 79<pre class="literal-block"> 80typedef <a href="./erase.html" class="identifier">erase</a>< s, <a href="./begin.html" class="identifier">begin</a><s>::type, <a href="./end.html" class="identifier">end</a><s>::type >::type t; 81</pre> 82</td> 83</tr> 84<tr class="field"><th class="field-name">Postcondition:</th><td class="field-body"><p class="first last"><tt class="literal"><span class="pre"><a href="./empty.html" class="identifier">empty</a><s>::value</span> <span class="pre">==</span> <span class="pre">true</span></tt>.</p> 85</td> 86</tr> 87</tbody> 88</table> 89</div> 90<div class="section" id="id217"> 91<h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3> 92<p>Amortized constant time.</p> 93</div> 94<div class="section" id="id218"> 95<h3><a class="subsection-title" href="#example" name="example">Example</a></h3> 96<pre class="literal-block"> 97typedef <a href="./vector-c.html" class="identifier">vector_c</a><int,1,3,5,7,9,11> odds; 98typedef <a href="./clear.html" class="identifier">clear</a><odds>::type nothing; 99 100<a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./empty.html" class="identifier">empty</a><nothing> )); 101</pre> 102</div> 103<div class="section" id="id219"> 104<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> 105<p><a class="reference internal" href="./extensible-sequence.html">Extensible Sequence</a>, <a class="reference internal" href="./extensible-associative-sequence.html">Extensible Associative Sequence</a>, <a class="reference internal" href="./erase.html">erase</a>, <a class="reference internal" href="./empty.html">empty</a>, <a class="reference internal" href="./begin.html">begin</a>, <a class="reference internal" href="./end.html">end</a></p> 106<!-- Sequences/Intrinsic Metafunctions//empty --> 107</div> 108</div> 109 110<div class="footer-separator"></div> 111<table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./begin.html" class="navigation-link">Prev</a> <a href="./empty.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./begin.html" class="navigation-link">Back</a> <a href="./empty.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./intrinsic-metafunctions.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> 112<td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> 113Distributed under the Boost Software License, Version 1.0. (See accompanying 114file 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> 115</html> 116