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| <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> |
| |
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| |
| <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> |
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