1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0.1 Transitional//EN"> 2 3<html> 4<head> 5<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 6<title>Boost.Flyweight Documentation - Future work</title> 7<link rel="stylesheet" href="style.css" type="text/css"> 8<link rel="start" href="examples.html"> 9<link rel="prev" href="tests.html"> 10<link rel="up" href="index.html"> 11<link rel="next" href="release_notes.html"> 12</head> 13 14<body> 15<h1><img src="../../../boost.png" alt="Boost logo" align= 16"middle" width="277" height="86">Boost.Flyweight Future work</h1> 17 18<div class="prev_link"><a href="tests.html"><img src="prev.gif" alt="examples" border="0"><br> 19Tests 20</a></div> 21<div class="up_link"><a href="index.html"><img src="up.gif" alt="index" border="0"><br> 22Index 23</a></div> 24<div class="next_link"><a href="release_notes.html"><img src="next.gif" alt="release notes" border="0"><br> 25Release notes 26</a></div><br clear="all" style="clear: all;"> 27<br clear="all" style="clear: all;"> 28 29<hr> 30 31<p> 32New functionalities can be included into future releases of Boost.Flyweight 33to meet the demands of users and to leverage upcoming C++ features 34and new Boost libraries. The following is a list of candidate additions. 35</p> 36 37<h2>Contents</h2> 38 39<ul> 40 <li><a href="#instrospection">Introspection API</a></li> 41 <li><a href="#rw_lock">Read/write locking policy</a></li> 42 <li><a href="#new_boost_libs">Integration with new Boost libraries</a></li> 43</ul> 44 45<h2><a name="instrospection">Introspection API</a></h2> 46 47<p> 48Currently there is no way to access the internal components of a 49<code>flyweight</code> instantiation (factory, holder, etc.) or even 50to know the types of these components. With such an API it would be 51possible to instrument and monitor the usage of Boost.Flyweight like in 52the following example: 53</p> 54 55<blockquote><pre> 56<span class=keyword>typedef</span> <span class=identifier>flyweight</span><span class=special><</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span><span class=special>></span> <span class=identifier>fw_type</span><span class=special>;</span> 57<span class=special>...</span> 58<span class=identifier>std</span><span class=special>::</span><span class=identifier>cout</span><span class=special><<</span><span class=string>"factory used: "</span><span class=special><<</span><span class=keyword>typeid</span><span class=special>(</span><span class=identifier>fw_type</span><span class=special>::</span><span class=identifier>factory_type</span><span class=special>).</span><span class=identifier>name</span><span class=special>()<<</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>endl</span><span class=special>;</span> 59<span class=identifier>std</span><span class=special>::</span><span class=identifier>cout</span><span class=special><<</span><span class=string>"values stored: "</span><span class=special><<</span><span class=identifier>fw_type</span><span class=special>::</span><span class=identifier>factory</span><span class=special>().</span><span class=identifier>size</span><span class=special>()<<</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>endl</span><span class=special>;</span> 60</pre></blockquote> 61 62<h2><a name="rw_lock">Read/write locking policy</a></h2> 63 64<p> 65The nature of the flyweight pattern implies that most accesses 66to the internal flyweight factory do not cause new insertions and can 67thus be considered read-only. This hints at the convenience of using 68a locking policy based on read/write locks such as those provided by 69<a href="../../../doc/html/thread/synchronization.html#thread.synchronization.mutex_concepts.shared_lockable">Boost.Thread</a>. 70Implementing a locking policy will also require extending the 71<a href="reference/factories.html#factory"><code>Factory</code></a> concept 72to allow for pure lookup operations. Tim Blechmann has provided a 73preliminary <a href="http://lists.boost.org/Archives/boost/2008/07/139414.php">implementation</a> 74of this idea. Before committing to this library extension it is 75necessary to do a profiling study to determine whether read/write 76locking actually improves performance. 77</p> 78 79<h2><a name="new_boost_libs">Integration with new Boost libraries</a></h2> 80 81<p> 82Recently accepted Boost libraries like 83<a href="http://lists.boost.org/boost-announce/2007/12/0149.php">Boost.Functional/Forward</a> 84and <a href="http://lists.boost.org/boost-announce/2007/12/0157.php">Boost.Functional/Factory</a> 85might be used in the future to replace some internal machinery of 86Boost.Flyweight. 87</p> 88 89<hr> 90 91<div class="prev_link"><a href="tests.html"><img src="prev.gif" alt="examples" border="0"><br> 92Tests 93</a></div> 94<div class="up_link"><a href="index.html"><img src="up.gif" alt="index" border="0"><br> 95Index 96</a></div> 97<div class="next_link"><a href="release_notes.html"><img src="next.gif" alt="release notes" border="0"><br> 98Release notes 99</a></div><br clear="all" style="clear: all;"> 100<br clear="all" style="clear: all;"> 101 102<br> 103 104<p>Revised April 24th 2019</p> 105 106<p>© Copyright 2006-2019 Joaquín M López Muñoz. 107Distributed under the Boost Software 108License, Version 1.0. (See accompanying file <a href="../../../LICENSE_1_0.txt"> 109LICENSE_1_0.txt</a> or copy at <a href="http://www.boost.org/LICENSE_1_0.txt"> 110http://www.boost.org/LICENSE_1_0.txt</a>) 111</p> 112 113</body> 114</html> 115
