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- BoostBook element rationale"><link rel="refentry" href="Assignable.html" title="Concept Assignable"><link rel="refentry" href="InputIterator.html" title="Concept InputIterator"><link rel="refentry" href="OutputIterator.html" title="Concept OutputIterator"><link rel="refentry" href="ForwardIterator.html" title="Concept ForwardIterator"><link rel="refentry" href="BidirectionalIterator.html" title="Concept BidirectionalIterator"><link rel="refentry" href="RandomAccessIterator.html" title="Concept RandomAccessIterator"><link rel="refentry" href="DefaultConstructible.html" title="Concept DefaultConstructible"><link rel="refentry" href="CopyConstructible.html" title="Concept CopyConstructible"><link rel="refentry" href="EqualityComparable.html" title="Concept EqualityComparable"><link rel="refentry" href="LessThanComparable.html" title="Concept LessThanComparable"><link rel="refentry" href="SignedInteger.html" title="Concept SignedInteger"><link rel="section" href="ref.html#ref.intro" title="Introduction"><link rel="section" href="ref.reference.html" title="Reference"><link rel="section" href="ref.ack.html" title="Acknowledgements"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" border="1" cellpadding="2" bgcolor="#007F7F"><tr><td bgcolor="#FFFFFF"><img src="../../c++boost.gif" alt="c++boost.gif (8819 bytes)" width="277" height="86"></td><td><a href="../../index.htm"><font color="#FFFFFF" size="4" face="Arial">Home</font></a></td><td><a href="libraries.html"><font color="#FFFFFF" size="4" face="Arial">Libraries</font></a></td><td><a href="../../people/people.htm"><font color="#FFFFFF" size="4" face="Arial">People</font></a></td><td><a href="../../more/faq.htm"><font color="#FFFFFF" size="4" face="Arial">FAQ</font></a></td><td><a href="../../more/index.htm"><font color="#FFFFFF" size="4" face="Arial">More</font></a></td></tr></table><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="ref"></a>Boost.Ref</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Jaakko</span> <span class="surname">Järvi</span></h3></div></div><div><div class="author"><h3 class="author"><span class="firstname">Peter</span> <span class="surname">Dimov</span></h3></div></div><div><div class="author"><h3 class="author"><span class="firstname">Douglas</span> <span class="surname">Gregor</span></h3></div></div><div><div class="author"><h3 class="author"><span class="firstname">Dave</span> <span class="surname">Abrahams</span></h3></div></div><div><p class="copyright">Copyright © 1999, 2000 Jaakko Järvi</p></div><div><p class="copyright">Copyright © 2001, 2002 Peter Dimov</p></div><div><p class="copyright">Copyright © 2002 David Abrahams</p></div><div><div class="legalnotice"><p>Permission to copy, use, modify, sell and distribute this
- software is granted provided this copyright notice appears in
- all copies. This software is provided "as is" without express
- or implied warranty, and with no claim as to its suitability for
- any purpose.
- </p></div></div></div><div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><a href="ref.html#ref.intro">Introduction</a></dt><dt><a href="ref.reference.html">Reference</a></dt><dd><dl><dt><a href="ref.reference.html#header.boost.ref.hpp">Header <boost/ref.hpp></a></dt></dl></dd><dt><a href="ref.ack.html">Acknowledgements</a></dt></dl></div><div class="section" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="ref.intro"></a>Introduction</h3></div></div><div></div></div><p>The Ref library is a small library that is useful for passing
- references to function templates (algorithms) that would usually
- take copies of their arguments. It defines the class template
- <tt class="computeroutput"><a href="class.boost.reference_wrapper.html" title="Class template reference_wrapper">boost::reference_wrapper<T></a></tt>,
- the two functions
- <tt class="computeroutput"><a href="class.boost.reference_wrapper.html#id2471260-bb">boost::ref</a></tt> and
- <tt class="computeroutput"><a href="class.boost.reference_wrapper.html#id2435969-bb">boost::cref</a></tt> that return
- instances of <tt class="computeroutput">boost::reference_wrapper<T></tt>, and the
- two traits classes
- <tt class="computeroutput"><a href="class.boost.is_reference_wrapper.html" title="Class template is_reference_wrapper">boost::is_reference_wrapper<T></a></tt>
- and
- <tt class="computeroutput"><a href="class.boost.unwrap_reference.html" title="Class template unwrap_reference">boost::unwrap_reference<T></a></tt>.</p><p>The purpose of
- <tt class="computeroutput">boost::reference_wrapper<T></tt> is to
- contain a reference to an object of type T. It is primarily used to
- "feed" references to function templates (algorithms) that take their
- parameter by value.</p><p>To support this usage,
- <tt class="computeroutput">boost::reference_wrapper<T></tt> provides an implicit
- conversion to <tt class="computeroutput">T&</tt>. This usually allows the function
- templates to work on references unmodified.</p><p><tt class="computeroutput">boost::reference_wrapper<T></tt> is
- both CopyConstructible and Assignable (ordinary references are not
- Assignable).</p><p>The expression <tt class="computeroutput">boost::ref(x)</tt>
- returns a
- <tt class="computeroutput">boost::reference_wrapper<X>(x)</tt> where X
- is the type of x. Similarly,
- <tt class="computeroutput">boost::cref(x)</tt> returns a
- <tt class="computeroutput">boost::reference_wrapper<X const>(x)</tt>.</p><p>The expression
- <tt class="computeroutput">boost::is_reference_wrapper<T>::value</tt>
- is true if T is a <tt class="computeroutput">reference_wrapper</tt>, and
- false otherwise.</p><p>The type-expression
- <tt class="computeroutput">boost::unwrap_reference<T>::type</tt> is T::type if T
- is a <tt class="computeroutput">reference_wrapper</tt>, T otherwise.</p></div></div><table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr><td align="left"><small>Last revised: March 15, 2003 at 23:12:35 GMT</small></td><td align="right"><small></small></td></tr></table><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="function.testsuite.html"><img src="images/prev.png" alt="Prev"></a> </td><td width="20%" align="center"><a accesskey="u" href="index.html"><img src="images/up.png" alt="Up"></a></td><td width="40%" align="right"> <a accesskey="n" href="ref.reference.html"><img src="images/next.png" alt="Next"></a></td></tr><tr><td width="40%" align="left" valign="top">Testsuite </td><td width="20%" align="center"><a accesskey="h" href="index.html"><img src="images/home.png" alt="Home"></a></td><td width="40%" align="right" valign="top"> Reference</td></tr></table></div></body></html>
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