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94 lines
2.7 KiB
HTML
94 lines
2.7 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<HTML>
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<HEAD>
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<TITLE>singleton - Singleton</TITLE>
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<LINK HREF="../pool.css" REL="stylesheet" TYPE="text/css">
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</HEAD>
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<BODY>
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<IMG SRC="../../../../c++boost.gif" WIDTH=276 HEIGHT=86 ALT="C++ Boost">
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<H1 ALIGN=CENTER>singleton - Singleton</H1>
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<P>
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<H2>Introduction</H2>
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<P>
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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.
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<P>
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<H2>Synopsis</H2>
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<PRE CLASS="code">namespace details {
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namespace pool {
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template <typename T>
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class singleton_default
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{
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private:
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singleton_default();
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public:
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typedef T object_type;
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static object_type & instance();
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};
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} // namespace pool
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} // namespace details</PRE>
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<P>
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<H2>Semantics</H2>
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<P>
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<TABLE BORDER ALIGN=CENTER>
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<CAPTION><EM>Symbol Table</EM></CAPTION>
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<TR><TH>Symbol<TH>Meaning
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<TR><TD CLASS="code">T<TD>Any class with a non-throwing default constructor and non-throwing destructor
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</TABLE>
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<P>
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<TABLE BORDER ALIGN=CENTER>
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<CAPTION><EM>Requirements satisfied by <SPAN CLASS="code">singleton_default<T></SPAN></EM></CAPTION>
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<TR><TH>Expression<TH>Return Type<TH>Assertion/Note/Pre/Post-Condition
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<TR><TD CLASS="code">singleton_default<T>::instance()<TD CLASS="code">T &<TD>Returns a reference to the singleton instance
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</TABLE>
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<P>
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<H2>Guarantees</H2>
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<P>
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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.
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<P>
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<H2>Details</H2>
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<P>
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For details on how we provide the guarantees above, see the comments in the header file.
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<P>
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<H2>Dependencies</H2>
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<P>
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None.
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<P>
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<H2>Future Directions</H2>
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<P>
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This header may be replaced by a Boost singleton library.
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<P>
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<HR>
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<P>
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Copyright © 2000, 2001 Stephen Cleary (scleary AT jerviswebb DOT com)
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<P>
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This file can be redistributed and/or modified under the terms found in <A HREF="../copyright.html">copyright.html</A>
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<P>
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This software and its documentation is provided "as is" without express or implied warranty, and with no claim as to its suitability for any purpose.
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</BODY>
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</HTML> |