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  26 <div class="titlepage"><div><div><h4 class="title">
  27 <a name="beast.ref.boost__beast__close_socket"></a><a class="link" href="boost__beast__close_socket.html" title="close_socket">close_socket</a>
  28 </h4></div></div></div>
  29 <p>
  30         <a class="indexterm" name="idm45873511416704"></a>
  31 Close a socket or socket-like object.
  32       </p>
  33 <h5>
  34 <a name="beast.ref.boost__beast__close_socket.h0"></a>
  35         <span class="phrase"><a name="beast.ref.boost__beast__close_socket.synopsis"></a></span><a class="link" href="boost__beast__close_socket.html#beast.ref.boost__beast__close_socket.synopsis">Synopsis</a>
  36       </h5>
  37 <p>
  38         Defined in header <code class="literal">&lt;<a href="../../../../../../boost/beast/core/stream_traits.hpp" target="_top">boost/beast/core/stream_traits.hpp</a>&gt;</code>
  39       </p>
  40 <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
  41     <span class="keyword">class</span> <span class="identifier">Socket</span><span class="special">&gt;</span>
  42 <span class="keyword">void</span>
  43 <span class="identifier">close_socket</span><span class="special">(</span>
  44     <span class="identifier">Socket</span><span class="special">&amp;</span> <span class="identifier">sock</span><span class="special">);</span>
  45 </pre>
  46 <h5>
  47 <a name="beast.ref.boost__beast__close_socket.h1"></a>
  48         <span class="phrase"><a name="beast.ref.boost__beast__close_socket.description"></a></span><a class="link" href="boost__beast__close_socket.html#beast.ref.boost__beast__close_socket.description">Description</a>
  49       </h5>
  50 <p>
  51         This function attempts to close an object representing a socket. In this
  52         context, a socket is an object for which an unqualified call to the function
  53         <code class="computeroutput"><span class="keyword">void</span> <span class="identifier">beast_close_socket</span><span class="special">(</span><span class="identifier">Socket</span><span class="special">&amp;)</span></code> is well-defined. The function <code class="computeroutput"><span class="identifier">beast_close_socket</span></code> is a <span class="emphasis"><em>customization
  54         point</em></span>, allowing user-defined types to provide an algorithm for
  55         performing the close operation by overloading this function for the type
  56         in question. Since the customization point is a function call, the normal
  57         rules for finding the correct overload are applied including the rules for
  58         argument-dependent lookup ("ADL"). This permits classes derived
  59         from a type for which a customization is provided to inherit the customization
  60         point. An overload for the networking class template <code class="computeroutput"><span class="identifier">net</span><span class="special">::</span><span class="identifier">basic_socket</span></code>
  61         is provided, which implements the close algorithm for all socket-like objects
  62         (hence the name of this customization point). When used in conjunction with
  63         <a class="link" href="boost__beast__get_lowest_layer.html" title="get_lowest_layer"><code class="computeroutput"><span class="identifier">get_lowest_layer</span></code></a>,
  64         a generic algorithm operating on a layered stream can perform a closure of
  65         the underlying socket without knowing the exact list of concrete types.
  66       </p>
  67 <h5>
  68 <a name="beast.ref.boost__beast__close_socket.h2"></a>
  69         <span class="phrase"><a name="beast.ref.boost__beast__close_socket.example_1"></a></span><a class="link" href="boost__beast__close_socket.html#beast.ref.boost__beast__close_socket.example_1">Example
  70         1</a>
  71       </h5>
  72 <p>
  73         The following generic function synchronously sends a message on the stream,
  74         then closes the socket.
  75       </p>
  76 <pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">WriteStream</span><span class="special">&gt;</span>
  77 <span class="keyword">void</span> <span class="identifier">hello_and_close</span> <span class="special">(</span><span class="identifier">WriteStream</span><span class="special">&amp;</span> <span class="identifier">stream</span><span class="special">)</span>
  78 <span class="special">{</span>
  79     <span class="identifier">net</span><span class="special">::</span><span class="identifier">write</span><span class="special">(</span><span class="identifier">stream</span><span class="special">,</span> <span class="identifier">net</span><span class="special">::</span><span class="identifier">const_buffer</span><span class="special">(</span><span class="string">"Hello, world!"</span><span class="special">,</span> <span class="number">13</span><span class="special">));</span>
  80     <span class="identifier">close_socket</span><span class="special">(</span><span class="identifier">get_lowest_layer</span><span class="special">(</span><span class="identifier">stream</span><span class="special">));</span>
  81 <span class="special">}</span>
  82 </pre>
  83 <p>
  84         To enable closure of user defined types, it is necessary to provide an overload
  85         of the function <code class="computeroutput"><span class="identifier">beast_close_socket</span></code>
  86         for the type.
  87       </p>
  88 <h5>
  89 <a name="beast.ref.boost__beast__close_socket.h3"></a>
  90         <span class="phrase"><a name="beast.ref.boost__beast__close_socket.example_2"></a></span><a class="link" href="boost__beast__close_socket.html#beast.ref.boost__beast__close_socket.example_2">Example
  91         2</a>
  92       </h5>
  93 <p>
  94         The following code declares a user-defined type which contains a private
  95         socket, and provides an overload of the customization point which closes
  96         the private socket.
  97       </p>
  98 <pre class="programlisting"><span class="keyword">class</span> <span class="identifier">my_socket</span>
  99 <span class="special">{</span>
 100     <span class="identifier">net</span><span class="special">::</span><span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">socket</span> <span class="identifier">sock_</span><span class="special">;</span>
 101
 102 <span class="keyword">public</span><span class="special">:</span>
 103     <span class="identifier">my_socket</span><span class="special">(</span><span class="identifier">net</span><span class="special">::</span><span class="identifier">io_context</span><span class="special">&amp;</span> <span class="identifier">ioc</span><span class="special">)</span>
 104         <span class="special">:</span> <span class="identifier">sock_</span><span class="special">(</span><span class="identifier">ioc</span><span class="special">)</span>
 105     <span class="special">{</span>
 106     <span class="special">}</span>
 107
 108     <span class="keyword">friend</span> <span class="keyword">void</span> <span class="identifier">beast_close_socket</span><span class="special">(</span><span class="identifier">my_socket</span><span class="special">&amp;</span> <span class="identifier">s</span><span class="special">)</span>
 109     <span class="special">{</span>
 110         <span class="identifier">error_code</span> <span class="identifier">ec</span><span class="special">;</span>
 111         <span class="identifier">s</span><span class="special">.</span><span class="identifier">sock_</span><span class="special">.</span><span class="identifier">close</span><span class="special">(</span><span class="identifier">ec</span><span class="special">);</span>
 112         <span class="comment">// ignore the error</span>
 113     <span class="special">}</span>
 114 <span class="special">};</span>
 115 </pre>
 116 <h5>
 117 <a name="beast.ref.boost__beast__close_socket.h4"></a>
 118         <span class="phrase"><a name="beast.ref.boost__beast__close_socket.parameters"></a></span><a class="link" href="boost__beast__close_socket.html#beast.ref.boost__beast__close_socket.parameters">Parameters</a>
 119       </h5>
 120 <div class="informaltable"><table class="table">
 121 <colgroup>
 122 <col>
 123 <col>
 124 </colgroup>
 125 <thead><tr>
 126 <th>
 127                 <p>
 128                   Name
 129                 </p>
 130               </th>
 131 <th>
 132                 <p>
 133                   Description
 134                 </p>
 135               </th>
 136 </tr></thead>
 137 <tbody><tr>
 138 <td>
 139                 <p>
 140                   <code class="computeroutput"><span class="identifier">sock</span></code>
 141                 </p>
 142               </td>
 143 <td>
 144                 <p>
 145                   The socket to close. If the customization point is not defined
 146                   for the type of this object, or one of its base classes, then a
 147                   compiler error results.
 148                 </p>
 149               </td>
 150 </tr></tbody>
 151 </table></div>
 152 <h5>
 153 <a name="beast.ref.boost__beast__close_socket.h5"></a>
 154         <span class="phrase"><a name="beast.ref.boost__beast__close_socket.see_also"></a></span><a class="link" href="boost__beast__close_socket.html#beast.ref.boost__beast__close_socket.see_also">See
 155         Also</a>
 156       </h5>
 157 <p>
 158         <a class="link" href="boost__beast__beast_close_socket.html" title="beast_close_socket"><code class="computeroutput"><span class="identifier">beast_close_socket</span></code></a>
 159       </p>
 160 <p>
 161         Convenience header <code class="literal">&lt;<a href="../../../../../../boost/beast/core.hpp" target="_top">boost/beast/core.hpp</a>&gt;</code>
 162       </p>
 163 </div>
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