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| <h1><img src="../../../../boost.png" alt="Boost logo" align= |
| "middle" width="277" height="86">Boost.Flyweight |
| Holders reference</h1> |
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| <h2>Contents</h2> |
| |
| <ul> |
| <li><a href="#holder">Holders and holder specifiers</a></li> |
| <li><a href="#holder_tag_synopsis">Header |
| <code>"boost/flyweight/holder_tag.hpp"</code> synopsis</a> |
| <ul> |
| <li><a href="#is_holder">Class template <code>is_holder</code></a></li> |
| <li><a href="#holder_construct">Class template <code>holder</code></a></li> |
| </ul> |
| </li> |
| <li><a href="#static_holder_fwd_synopsis">Header |
| <code>"boost/flyweight/static_holder_fwd.hpp"</code> synopsis</a> |
| </li> |
| <li><a href="#static_holder_synopsis">Header |
| <code>"boost/flyweight/static_holder.hpp"</code> synopsis</a> |
| <ul> |
| <li><a href="#static_holder_class">Class template <code>static_holder_class</code></a></li> |
| <li><a href="#static_holder">Class <code>static_holder</code></a></li> |
| </ul> |
| </li> |
| <li><a href="#intermodule_holder_fwd_synopsis">Header |
| <code>"boost/flyweight/intermodule_holder_fwd.hpp"</code> synopsis</a> |
| </li> |
| <li><a href="#intermodule_holder_synopsis">Header |
| <code>"boost/flyweight/intermodule_holder.hpp"</code> synopsis</a> |
| <ul> |
| <li><a href="#intermodule_holder_class">Class template <code>intermodule_holder_class</code></a></li> |
| <li><a href="#intermodule_holder">Class <code>intermodule_holder</code></a></li> |
| </ul> |
| </li> |
| </ul> |
| |
| <h2><a name="holder">Holders and holder specifiers</a></h2> |
| |
| <p> |
| Given a type <code>C</code>, a type <code>Holder</code> is said to be a <i>holder |
| of <code>C</code></i> if the expression <code>Holder::get()</code> returns |
| a reference to a default initialized <code>C</code> object unique to |
| <code>Holder</code>. No invocation of <code>Holder::get()</code>, except possibly |
| the first one in the program, does throw. |
| <a href="flyweight.html#flyweight"><code>flyweight</code></a> |
| privately uses a holder to instantiate a <a href="factories.html#factory">factory</a> |
| and some additional data (like a <a href="locking.html#preliminary">mutex</a> for |
| internal synchronization) unique to each instantiation type of the class template. |
| </p> |
| |
| <p> |
| A type <code>S</code> is a <i>holder specifier</i> if: |
| <ol> |
| <li>One of the following conditions is satisfied: |
| <ol type="a"> |
| <li><a href="#is_holder"><code>is_holder<S>::type</code></a> is |
| <a href="../../../mpl/doc/refmanual/bool.html"><code>boost::mpl::true_</code></a>,</li> |
| <li><code>S</code> is of the form <a href="#holder_construct"><code>holder<S'></code></a>.</li> |
| </ol> |
| </li> |
| <li><code>S</code>, or <code>S'</code> if (b) applies, is an |
| <a href="../../../mpl/doc/refmanual/lambda-expression.html"><code>MPL Lambda |
| Expression</code></a> such that invoking it with type <code>C</code> resolves to |
| a holder of <code>C</code>. |
| </li> |
| </ol> |
| </p> |
| |
| <h2><a name="holder_tag_synopsis">Header |
| <a href="../../../../boost/flyweight/holder_tag.hpp"><code>"boost/flyweight/holder_tag.hpp"</code></a> synopsis</a></h2> |
| |
| <blockquote><pre> |
| <span class=keyword>namespace</span> <span class=identifier>boost</span><span class=special>{</span> |
| |
| <span class=keyword>namespace</span> <span class=identifier>flyweights</span><span class=special>{</span> |
| |
| <span class=keyword>struct</span> <span class=identifier>holder_marker</span><span class=special>;</span> |
| |
| <span class=keyword>template</span><span class=special><</span><span class=keyword>typename</span> <span class=identifier>T</span><span class=special>></span> |
| <span class=keyword>struct</span> <span class=identifier>is_holder</span><span class=special>;</span> |
| |
| <span class=keyword>template</span><span class=special><</span><span class=keyword>typename</span> <span class=identifier>T</span><span class=special>></span> |
| <span class=keyword>struct</span> <span class=identifier>holder</span><span class=special>;</span> |
| |
| <span class=special>}</span> <span class=comment>// namespace boost::flyweights</span> |
| |
| <span class=special>}</span> <span class=comment>// namespace boost</span> |
| </pre></blockquote> |
| |
| <h3><a name="is_holder">Class template <code>is_holder</code></a></h3> |
| |
| <p> |
| Unless specialized by the user, <code>is_holder<T>::type</code> is |
| <a href="../../../mpl/doc/refmanual/bool.html"><code>boost::mpl::true_</code></a> |
| if <code>T</code> is derived from <code>holder_marker</code>, and it is |
| <a href="../../../mpl/doc/refmanual/bool.html"><code>boost::mpl::false_</code></a> |
| otherwise. |
| </p> |
| |
| <h3><a name="holder_construct">Class template <code>holder</code></a></h3> |
| |
| <p> |
| <code>holder<T></code> is a syntactic construct meant to indicate |
| that <code>T</code> is a holder specifier without resorting to the |
| mechanisms provided by the <code>is_holder</code> class template. |
| </p> |
| |
| <h2><a name="static_holder_fwd_synopsis">Header |
| <a href="../../../../boost/flyweight/static_holder_fwd.hpp"><code>"boost/flyweight/static_holder_fwd.hpp"</code></a> synopsis</a></h2> |
| |
| <blockquote><pre> |
| <span class=keyword>namespace</span> <span class=identifier>boost</span><span class=special>{</span> |
| |
| <span class=keyword>namespace</span> <span class=identifier>flyweights</span><span class=special>{</span> |
| |
| <span class=keyword>template</span><span class=special><</span><span class=keyword>typename</span> <span class=identifier>C</span><span class=special>></span> |
| <span class=keyword>struct</span> <span class=identifier>static_holder_class</span><span class=special>;</span> |
| |
| <span class=keyword>struct</span> <span class=identifier>static_holder</span><span class=special>;</span> |
| |
| <span class=special>}</span> <span class=comment>// namespace boost::flyweights</span> |
| |
| <span class=special>}</span> <span class=comment>// namespace boost</span> |
| </pre></blockquote> |
| |
| <p> |
| <code>static_holder_fwd.hpp</code> forward declares |
| <a href="#static_holder_class"><code>static_holder_class</code></a> |
| and <a href="#static_holder"><code>static_holder</code></a>. |
| </p> |
| |
| <h2><a name="static_holder_synopsis">Header |
| <a href="../../../../boost/flyweight/static_holder.hpp"><code>"boost/flyweight/static_holder.hpp"</code></a> synopsis</a></h2> |
| |
| <h3><a name="static_holder_class">Class template <code>static_holder_class</code></a></h3> |
| |
| <p> |
| <code>static_holder_class<C></code> keeps its unique instance of <code>C</code> as a |
| local static object. |
| </p> |
| |
| <h3><a name="static_holder">Class <code>static_holder</code></a></h3> |
| |
| <p> |
| <a href="#holder"><code>Holder Specifier</code></a> for <a href="#static_holder_class"><code>static_holder_class</code></a>. |
| </p> |
| |
| <h2><a name="intermodule_holder_fwd_synopsis">Header |
| <a href="../../../../boost/flyweight/intermodule_holder_fwd.hpp"><code>"boost/flyweight/intermodule_holder_fwd.hpp"</code></a> synopsis</a></h2> |
| |
| <blockquote><pre> |
| <span class=keyword>namespace</span> <span class=identifier>boost</span><span class=special>{</span> |
| |
| <span class=keyword>namespace</span> <span class=identifier>flyweights</span><span class=special>{</span> |
| |
| <span class=keyword>template</span><span class=special><</span><span class=keyword>typename</span> <span class=identifier>C</span><span class=special>></span> |
| <span class=keyword>struct</span> <span class=identifier>intermodule_holder_class</span><span class=special>;</span> |
| |
| <span class=keyword>struct</span> <span class=identifier>intermodule_holder</span><span class=special>;</span> |
| |
| <span class=special>}</span> <span class=comment>// namespace boost::flyweights</span> |
| |
| <span class=special>}</span> <span class=comment>// namespace boost</span> |
| </pre></blockquote> |
| |
| <p> |
| <code>intermodule_holder_fwd.hpp</code> forward declares |
| <a href="#intermodule_holder_class"><code>intermodule_holder_class</code></a> |
| and <a href="#intermodule_holder"><code>intermodule_holder</code></a>. |
| </p> |
| |
| <h2><a name="intermodule_holder_synopsis">Header |
| <a href="../../../../boost/flyweight/intermodule_holder.hpp"><code>"boost/flyweight/intermodule_holder.hpp"</code></a> synopsis</a></h2> |
| |
| <h3><a name="intermodule_holder_class">Class template <code>intermodule_holder_class</code></a></h3> |
| |
| <p> |
| <code>intermodule_holder_class<C></code> maintains a <code>C</code> |
| instance which is unique even across different dynamically linked modules of |
| the program using this same type. In general, this guarantee is not provided by |
| <a href="#static_holder_class"><code>static_holder_class</code></a>, as most |
| C++ implementations are not able to merge duplicates of static variables stored |
| in different dynamic modules of a program. |
| </p> |
| |
| <h3><a name="intermodule_holder">Class <code>intermodule_holder</code></a></h3> |
| |
| <p> |
| <a href="#holder"><code>Holder Specifier</code></a> for <a href="#intermodule_holder_class"><code>intermodule_holder_class</code></a>. |
| </p> |
| |
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| <p>Revised August 11th 2008</p> |
| |
| <p>© Copyright 2006-2008 Joaquín M López Muñoz. |
| 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>) |
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