<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Language" content="en-us"> <meta http-equiv="Content-Type" content="text/html; charset=us-ascii"> <link href="../pool.css" rel="stylesheet" type="text/css"> <title>singleton - Singleton</title> </head> <body> <img src="../../../../boost.png" width="276" height="86" alt="C++ Boost"> <h1 align="center">singleton - Singleton</h1> <h2>Introduction</h2> <p>detail/singleton.hpp provides a way to access a Singleton of a class type. This is <strong>not</strong> a general Singleton solution! It is restricted in that the class type must have a default constructor.</p> <h2>Synopsis</h2> <pre class="code"> namespace details { namespace pool { template <typename T> class singleton_default { private: singleton_default(); public: typedef T object_type; static object_type & instance(); }; } // namespace pool } // namespace details </pre> <h2>Semantics</h2> <table border align="center" summary=""> <caption> <em>Symbol Table</em> </caption> <tr> <th>Symbol</th> <th>Meaning</th> </tr> <tr> <td class="code">T</td> <td>Any class with a non-throwing default constructor and non-throwing destructor</td> </tr> </table><br> <table border align="center" summary=""> <caption> <em>Requirements satisfied by <span class= "code">singleton_default<T></span></em> </caption> <tr> <th>Expression</th> <th>Return Type</th> <th>Assertion/Note/Pre/Post-Condition</th> </tr> <tr> <td class="code">singleton_default<T>::instance()</td> <td class="code">T &</td> <td>Returns a reference to the singleton instance</td> </tr> </table> <h2>Guarantees</h2> <p>The singleton instance is guaranteed to be constructed before <span class="code">main()</span> begins, and destructed after <span class= "code">main()</span> ends. Furthermore, it is guaranteed to be constructed before the first call to <span class= "code">singleton_default<T>::instance()</span> is complete (even if called before <span class="code">main()</span> begins). Thus, if there are not multiple threads running except within <span class= "code">main()</span>, and if all access to the singleton is restricted by mutexes, then this guarantee allows a thread-safe singleton.</p> <h2>Details</h2> <p>For details on how we provide the guarantees above, see the comments in the header file.</p> <h2>Dependencies</h2> <p>None.</p> <h2>Future Directions</h2> <p>This header may be replaced by a Boost singleton library.</p> <hr> <p><a href="http://validator.w3.org/check?uri=referer"><img border="0" src= "../../../../doc/images/valid-html401.png" alt="Valid HTML 4.01 Transitional" height="31" width="88"></a></p> <p>Revised <!--webbot bot="Timestamp" s-type="EDITED" s-format="%d %B, %Y" startspan -->05 December, 2006<!--webbot bot="Timestamp" endspan i-checksum="38516" --></p> <p><i>Copyright © 2000, 2001 Stephen Cleary (scleary AT jerviswebb DOT com)</i></p> <p><i>Distributed under the Boost Software License, Version 1.0. (See accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or copy at <a href= "http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</a>)</i></p> </body> </html>