1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<HTML>
<HEAD>
<TITLE>singleton - Singleton</TITLE>
<LINK HREF="../pool.css" REL="stylesheet" TYPE="text/css">
</HEAD>
<BODY>
<IMG SRC="../../../../c++boost.gif" WIDTH=276 HEIGHT=86 ALT="C++ Boost">
<H1 ALIGN=CENTER>singleton - Singleton</H1>
<P>
<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>
<P>
<H2>Semantics</H2>
<P>
<TABLE BORDER ALIGN=CENTER>
<CAPTION><EM>Symbol Table</EM></CAPTION>
<TR><TH>Symbol<TH>Meaning
<TR><TD CLASS="code">T<TD>Any class with a non-throwing default constructor and non-throwing destructor
</TABLE>
<P>
<TABLE BORDER ALIGN=CENTER>
<CAPTION><EM>Requirements satisfied by <SPAN CLASS="code">singleton_default<T></SPAN></EM></CAPTION>
<TR><TH>Expression<TH>Return Type<TH>Assertion/Note/Pre/Post-Condition
<TR><TD CLASS="code">singleton_default<T>::instance()<TD CLASS="code">T &<TD>Returns a reference to the singleton instance
</TABLE>
<P>
<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>
Copyright © 2000, 2001 Stephen Cleary (<A HREF="mailto:shammah@voyager.net">shammah@voyager.net</A>)
<P>
This file can be redistributed and/or modified under the terms found in <A HREF="../copyright.html">copyright.html</A>
<P>
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.
</BODY>
</HTML>
|
