projects / ceph.git / blame
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1 | <!doctype HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| 2 | <html> | |
| 3 | <!-- | |
| 4 | (C) Copyright 2002-4 Robert Ramey - http://www.rrsd.com . | |
| 5 | Use, modification and distribution is subject to the Boost Software | |
| 6 | License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at | |
| 7 | http://www.boost.org/LICENSE_1_0.txt) | |
| 8 | --> | |
| 9 | <head> | |
| 10 | <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> | |
| 11 | <link rel="stylesheet" type="text/css" href="../../../boost.css"> | |
| 12 | <link rel="stylesheet" type="text/css" href="style.css"> | |
| 13 | <title>Serialization - <code style="white-space: normal">state_saver</code></title> | |
| 14 | </head> | |
| 15 | <body link="#0000ff" vlink="#800080"> | |
| 16 | <table border="0" cellpadding="7" cellspacing="0" width="100%" summary="header"> | |
| 17 | <tr> | |
| 18 | <td valign="top" width="300"> | |
| 19 | <h3><a href="../../../index.htm"><img height="86" width="277" alt="C++ Boost" src="../../../boost.png" border="0"></a></h3> | |
| 20 | </td> | |
| 21 | <td valign="top"> | |
| 22 | <h1 align="center">Serialization</h1> | |
| 23 | <h2 align="center"><code style="white-space: normal">state_saver</code</h2> | |
| 24 | </td> | |
| 25 | </tr> | |
| 26 | </table> | |
| 27 | <hr> | |
| 28 | <p> | |
| 29 | Sometimes a certain value has to change only for a limited scope. | |
| 30 | This class wrapper saves a copy of the current state of some object, | |
| 31 | and resets the object's state at destruction time, undoing any change the object | |
| 32 | may have gone through. Here is the interface: | |
| 33 | ||
| 34 | <pre><code> | |
| 35 | template<class T> | |
| 36 | // T requirements: | |
| 37 | // - POD or object semantic (cannot be reference, function, ...) | |
| 38 | // - copy constructor | |
| 39 | // - operator = (no-throw one preferred) | |
| 40 | class state_saver : private boost::noncopyable | |
| 41 | { | |
| 42 | private: | |
| 43 | ... // implementation | |
| 44 | ||
| 45 | public: | |
| 46 | state_saver(T & object); | |
| 47 | ~state_saver(); | |
| 48 | }; | |
| 49 | </code></pre> | |
| 50 | ||
| 51 | The complete implementation can be found | |
| 52 | <a target="state_saver" href="../../../boost/serialization/state_saver.hpp">here</a> | |
| 53 | ||
| 54 | The following illustrates how this is expected to be used. | |
| 55 | ||
| 56 | <pre><code> | |
| 57 | #include <boost/state_saver.hpp> | |
| 58 | ||
| 59 | void func(A & a) | |
| 60 | boost::state_saver<A> s(a); | |
| 61 | ... // alter state of a by calling non-const functions | |
| 62 | ... // call other functions | |
| 63 | // original state of a automatically restored on exit | |
| 64 | } | |
| 65 | </pre></code> | |
| 66 | ||
| 67 | <h3>History</h3> | |
| 68 | This is a generalization of Daryle Walker's | |
| 69 | <a href="../../../libs/io/doc/ios_state.html">io_state_saver</a> library. | |
| 70 | <p> | |
| 71 | Robert Ramey made an initial version for the serialization library. | |
| 72 | <p> | |
| 73 | Pavel Vozenilek made several non-obvious refinements to make it more | |
| 74 | secure and boost friendly | |
| 75 | ||
| 76 | <hr> | |
| 77 | <p><i>© Copyright <a href="http://www.rrsd.com">Robert Ramey</a> 2002-2004. | |
| 78 | Distributed under the Boost Software License, Version 1.0. (See | |
| 79 | accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
| 80 | </i></p> | |
| 81 | </body> | |
| 82 | </html> |