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utility/noncopyable : fix #6578.

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[SVN r83869]
This commit is contained in:
Vicente J. Botet Escriba 2013-04-13 13:49:52 +00:00
parent 2eda3f5299
commit 4080fe22e3
2 changed files with 22 additions and 6 deletions
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18
include/boost/noncopyable.hpp
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@ -9,6 +9,8 @@
#ifndef BOOST_NONCOPYABLE_HPP_INCLUDED
#define BOOST_NONCOPYABLE_HPP_INCLUDED
#include <boost/config.hpp>
namespace boost {
// Private copy constructor and copy assignment ensure classes derived from
@ -21,11 +23,21 @@ namespace noncopyable_ // protection from unintended ADL
class noncopyable
{
protected:
noncopyable() {}
#ifndef BOOST_NO_DEFAULTED_FUNCTIONS
BOOST_CONSTEXPR noncopyable() = default;
~noncopyable() = default;
#else
noncopyable() {}
~noncopyable() {}
private: // emphasize the following members are private
#endif
#ifndef BOOST_NO_DELETED_FUNCTIONS
noncopyable( const noncopyable& ) = delete;
noncopyable& operator=( const noncopyable& ) = delete;
#else
private: // emphasize the following members are private
noncopyable( const noncopyable& );
const noncopyable& operator=( const noncopyable& );
noncopyable& operator=( const noncopyable& );
#endif
};
}

10
utility.htm
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@ -84,8 +84,10 @@ const std::list&lt;T&gt;::iterator next = boost::next(prev, 2);</pre>
will prevent the otherwise implicitly-generated functions (which don't have the
proper semantics) from becoming a trap for other programmers.</p>
<p>The traditional way to deal with these is to declare a private copy constructor
and copy assignment, and then document why this is done.&nbsp; But deriving
from <b>noncopyable</b> is simpler and clearer, and doesn't require additional
and copy assignment, and then document why this is done.&nbsp; A new alternative
was introduced in C++2011, declaring a copy constructor and a copy assignment
operator, but marking both as <code>delete</code>d.&nbsp; Deriving
from <b>noncopyable</b> is simpler and clearer, and doesn't require additional
documentation.</p>
<p>The program <a href="noncopyable_test.cpp">noncopyable_test.cpp</a> can be used
to verify class <b>noncopyable</b> works as expected. It has have been run
@ -106,7 +108,9 @@ class ResourceLadenFileSystem : boost::noncopyable {
about the effect on compiler optimization of adding (even trivial inline)
destructor declarations. He says &quot;Probably this concern is misplaced,
because noncopyable will be used mostly for classes which own resources and
thus have non-trivial destruction semantics.&quot;</p>
thus have non-trivial destruction semantics.&quot;&nbsp; With C++2011, using an
optimized and trivial constructor and similar destructor can be enforced by
declaring both and marking them <code>default</code>.</p>
<h2><a name="addressof">Function template addressof()</a></h2>
<p>Function <strong>addressof()</strong> returns the address of an object.</p>
<blockquote>