forked from boostorg/bind
Make this a forwarding header to the BoostBook-generated documentation
[SVN r17738]
This commit is contained in:
Douglas Gregor
200
ref.html
200
ref.html
@@ -1,195 +1,9 @@
|
||||
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
|
||||
<html>
|
||||
<head>
|
||||
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
|
||||
<title>Boost: ref.hpp documentation</title>
|
||||
</head>
|
||||
<body bgcolor="White">
|
||||
<table border="0" width="100%">
|
||||
<tr>
|
||||
<td width="277">
|
||||
<img src="../../c++boost.gif" alt="c++boost.gif (8819 bytes)" width="277" height="86">
|
||||
</td>
|
||||
<td align="center">
|
||||
<table border="0">
|
||||
<tr>
|
||||
<td nowrap><h1>ref.hpp</h1>
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td align="right" nowrap><small> 1.00.0004 (2002-01-27)</small></td>
|
||||
</tr>
|
||||
</table>
|
||||
</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td colspan="2" height="64"> </td>
|
||||
</tr>
|
||||
</table>
|
||||
<h2>Files</h2>
|
||||
<ul>
|
||||
<li>
|
||||
<a href="../../boost/ref.hpp">ref.hpp</a>
|
||||
</ul>
|
||||
<h2>Purpose</h2>
|
||||
<p>
|
||||
The header <a href="../../boost/ref.hpp">boost/ref.hpp</a> defines the class
|
||||
template <b>boost::reference_wrapper<T></b>, the two functions <b>boost::ref</b>
|
||||
and <b>boost::cref</b> that return instances of <b>boost::reference_wrapper<T></b>,
|
||||
and the two traits classes <b>boost::is_reference_wrapper<T></b> and <b>boost::unwrap_reference<T></b>.
|
||||
</p>
|
||||
<p>
|
||||
The purpose of <b>boost::reference_wrapper<T></b> is to contain a
|
||||
reference to an object of type <b>T</b>. It is primarily used to "feed"
|
||||
references to function templates (algorithms) that take their parameter by
|
||||
value.
|
||||
</p>
|
||||
<p>
|
||||
To support this usage, <b>boost::reference_wrapper<T></b> provides an
|
||||
implicit conversion to <b>T &</b>. This usually allows the function
|
||||
templates to work on references unmodified.
|
||||
</p>
|
||||
<p>
|
||||
<b>boost::reference_wrapper<T></b> is both <b>CopyConstructible</b> and <b>Assignable</b>
|
||||
(ordinary references are not <b>Assignable</b>).
|
||||
</p>
|
||||
<p>
|
||||
The expression <b>boost::ref(x)</b> returns a <b>boost::reference_wrapper<X>(x)</b>
|
||||
where <b>X</b> is the type of <b>x</b>. Similarly, <b>boost::cref(x)</b> returns
|
||||
a <b>boost::reference_wrapper<X const>(x)</b>.
|
||||
</p>
|
||||
<p>
|
||||
The expression <b>boost::is_reference_wrapper<T>::value</b> is <b>true</b>
|
||||
if <b>T</b> is a <b>reference_wrapper</b>, and <b>false</b>
|
||||
otherwise.
|
||||
</p>
|
||||
<p>
|
||||
The type-expression <b>boost::unwrap_reference<T>::type</b> is <b>T::type</b>
|
||||
if <b>T</b> is a <b>reference_wrapper</b>, <b>T</b> otherwise.
|
||||
</p>
|
||||
<h2>Interface</h2>
|
||||
<h3>Synopsis</h3>
|
||||
<pre>
|
||||
namespace boost
|
||||
{
|
||||
template<class T> class <a href="#reference_wrapper">reference_wrapper</a>;
|
||||
template<class T> reference_wrapper<T> <a href="#ref">ref</a>(T & t);
|
||||
template<class T> reference_wrapper<T const> <a href="#cref">cref</a>(T const & t);
|
||||
template<class T> class is_reference_wrapper<T const>;
|
||||
template<class T> class unwrap_reference<T const>;
|
||||
}
|
||||
</pre>
|
||||
<h3><a name="reference_wrapper">reference_wrapper</a></h3>
|
||||
<pre>
|
||||
template<class T> class reference_wrapper
|
||||
{
|
||||
public:
|
||||
typedef T type;
|
||||
|
||||
explicit <a href="#rt_construct">reference_wrapper</a>(T & t);
|
||||
|
||||
<a href="#rt_operator">operator T &</a> () const;
|
||||
|
||||
T & <a href="#rt_get">get</a>() const;
|
||||
T* <a href="#rt_get_pointer">get_pointer</a>() const;
|
||||
};
|
||||
</pre>
|
||||
<h4><a name="rt_construct">explicit reference_wrapper(T & t)</a></h4>
|
||||
<blockquote>
|
||||
<p>
|
||||
<b>Effects:</b> Constructs a <b>reference_wrapper</b> object that stores a
|
||||
reference to <b>t</b>.
|
||||
</p>
|
||||
<p>
|
||||
<b>Throws:</b> Nothing.
|
||||
</p>
|
||||
</blockquote>
|
||||
<h4><a name="rt_operator">operator T & () const</a></h4>
|
||||
<blockquote>
|
||||
<p>
|
||||
<b>Returns:</b> the stored reference.
|
||||
</p>
|
||||
<p>
|
||||
<b>Throws:</b> Nothing.
|
||||
</p>
|
||||
</blockquote>
|
||||
<h4><a name="rt_get">T & get() const</a></h4>
|
||||
<blockquote>
|
||||
<p>
|
||||
<b>Returns:</b> the stored reference.
|
||||
</p>
|
||||
<p>
|
||||
<b>Throws:</b> Nothing.
|
||||
</p>
|
||||
</blockquote>
|
||||
<h4><a name="rt_get_pointer">T* get_pointer() const</a></h4>
|
||||
<blockquote>
|
||||
<p>
|
||||
<b>Returns:</b> a pointer to the stored object.
|
||||
</p>
|
||||
<p>
|
||||
<b>Throws:</b> Nothing.
|
||||
</p>
|
||||
</blockquote>
|
||||
<h3><a name="ref">ref</a></h3>
|
||||
<pre>
|
||||
template<class T> reference_wrapper<T> ref(T & t);
|
||||
</pre>
|
||||
<blockquote>
|
||||
<p>
|
||||
<b>Returns:</b> <tt>reference_wrapper<T>(t)</tt>.
|
||||
</p>
|
||||
<p>
|
||||
<b>Throws:</b> Nothing.
|
||||
</p>
|
||||
</blockquote>
|
||||
<h3><a name="cref">cref</a></h3>
|
||||
<pre>
|
||||
template<class T> reference_wrapper<T const> cref(T const & t);
|
||||
</pre>
|
||||
<blockquote>
|
||||
<p>
|
||||
<b>Returns:</b> <tt>reference_wrapper<T const>(t)</tt>.
|
||||
</p>
|
||||
<p>
|
||||
<b>Throws:</b> Nothing.
|
||||
</p>
|
||||
</blockquote>
|
||||
<h3><a name="is_reference_wrapper">is_reference_wrapper</a></h3>
|
||||
<pre>
|
||||
template<class T> class is_reference_wrapper<T const>
|
||||
{
|
||||
public:
|
||||
static bool value = <i>unspecified</i>;
|
||||
};
|
||||
</pre>
|
||||
Value is <b>true</b> iff <tt>T</tt> is a specialization of <tt>reference_wrapper</tt>.
|
||||
<h3><a name="unwrap_reference">unwrap_reference</a></h3>
|
||||
<pre>
|
||||
template<class T> class unwrap_reference<T const>
|
||||
{
|
||||
public:
|
||||
typedef <i>unspecified</i> type;
|
||||
};
|
||||
</pre>
|
||||
<tt>type</tt> is equivalent to <tt>T::type</tt> if <tt>T</tt> is a
|
||||
specialization of <tt>reference_wrapper</tt>. Otherwise <tt>type</tt> is
|
||||
equivalent to <tt>T</tt>.
|
||||
<h2>Acknowledgements</h2>
|
||||
<p>
|
||||
<b>ref</b> and <b>cref</b> were originally part of the Boost.Tuple library by <a href="../../people/jaakko_jarvi.htm">
|
||||
Jaakko Järvi</a>. They were "promoted to <b>boost::</b> status" by <a href="../../people/peter_dimov.htm">
|
||||
Peter Dimov</a> because they are generally useful. <a href="../../people/doug_gregor.html">
|
||||
Douglas Gregor</a> and <a href="../../people/dave_abrahams.htm">Dave Abrahams</a>
|
||||
contributed <tt>is_reference_wrapper</tt> and <tt>unwrap_reference</tt>.
|
||||
</p>
|
||||
<p><br>
|
||||
<br>
|
||||
<br>
|
||||
<small>Copyright © 2001 by Peter Dimov and Multi Media Ltd. Permission to
|
||||
copy, use, modify, sell and distribute this document is granted provided this
|
||||
copyright notice appears in all copies. This document is provided "as
|
||||
is" without express or implied warranty, and with no claim as to its
|
||||
suitability for any purpose.</small></p>
|
||||
</body>
|
||||
<head>
|
||||
<meta http-equiv="refresh" content="0; URL=../../doc/html/ref.html">
|
||||
</head>
|
||||
<body>
|
||||
Automatic redirection failed, please go to
|
||||
<a href="../../doc/html/ref.html">../../doc/html/ref.html</a>
|
||||
</body>
|
||||
</html>
|
||||
|
||||
Reference in New Issue
Block a user