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| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="boost_asio.reference.connect.overload5"></a><a class="link" href="overload5.html" title="connect (5 of 8 overloads)">connect (5 |
| of 8 overloads)</a> |
| </h4></div></div></div> |
| <p> |
| Establishes a socket connection by trying each endpoint in a sequence. |
| </p> |
| <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> |
| <span class="keyword">typename</span> <a class="link" href="../Protocol.html" title="Protocol requirements">Protocol</a><span class="special">,</span> |
| <span class="keyword">typename</span> <a class="link" href="../SocketService.html" title="Socket service requirements">SocketService</a><span class="special">,</span> |
| <span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">,</span> |
| <span class="keyword">typename</span> <span class="identifier">ConnectCondition</span><span class="special">></span> |
| <span class="identifier">Iterator</span> <span class="identifier">connect</span><span class="special">(</span> |
| <span class="identifier">basic_socket</span><span class="special"><</span> <span class="identifier">Protocol</span><span class="special">,</span> <span class="identifier">SocketService</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">s</span><span class="special">,</span> |
| <span class="identifier">Iterator</span> <span class="identifier">begin</span><span class="special">,</span> |
| <span class="identifier">ConnectCondition</span> <span class="identifier">connect_condition</span><span class="special">);</span> |
| </pre> |
| <p> |
| This function attempts to connect a socket to one of a sequence of endpoints. |
| It does this by repeated calls to the socket's <code class="computeroutput"><span class="identifier">connect</span></code> |
| member function, once for each endpoint in the sequence, until a connection |
| is successfully established. |
| </p> |
| <a name="boost_asio.reference.connect.overload5.parameters"></a><h6> |
| <a name="boost_asio.reference.connect.overload5.parameters-heading"></a> |
| <a class="link" href="overload5.html#boost_asio.reference.connect.overload5.parameters">Parameters</a> |
| </h6> |
| <div class="variablelist"> |
| <p class="title"><b></b></p> |
| <dl> |
| <dt><span class="term">s</span></dt> |
| <dd><p> |
| The socket to be connected. If the socket is already open, it will |
| be closed. |
| </p></dd> |
| <dt><span class="term">begin</span></dt> |
| <dd><p> |
| An iterator pointing to the start of a sequence of endpoints. |
| </p></dd> |
| <dt><span class="term">connect_condition</span></dt> |
| <dd> |
| <p> |
| A function object that is called prior to each connection attempt. |
| The signature of the function object must be: |
| </p> |
| <pre class="programlisting"><span class="identifier">Iterator</span> <span class="identifier">connect_condition</span><span class="special">(</span> |
| <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">ec</span><span class="special">,</span> |
| <span class="identifier">Iterator</span> <span class="identifier">next</span><span class="special">);</span> |
| </pre> |
| <p> |
| The <code class="computeroutput"><span class="identifier">ec</span></code> parameter |
| contains the result from the most recent connect operation. Before |
| the first connection attempt, <code class="computeroutput"><span class="identifier">ec</span></code> |
| is always set to indicate success. The <code class="computeroutput"><span class="identifier">next</span></code> |
| parameter is an iterator pointing to the next endpoint to be tried. |
| The function object should return the next iterator, but is permitted |
| to return a different iterator so that endpoints may be skipped. |
| The implementation guarantees that the function object will never |
| be called with the end iterator. |
| </p> |
| </dd> |
| </dl> |
| </div> |
| <a name="boost_asio.reference.connect.overload5.return_value"></a><h6> |
| <a name="boost_asio.reference.connect.overload5.return_value-heading"></a> |
| <a class="link" href="overload5.html#boost_asio.reference.connect.overload5.return_value">Return |
| Value</a> |
| </h6> |
| <p> |
| On success, an iterator denoting the successfully connected endpoint. Otherwise, |
| the end iterator. |
| </p> |
| <a name="boost_asio.reference.connect.overload5.exceptions"></a><h6> |
| <a name="boost_asio.reference.connect.overload5.exceptions-heading"></a> |
| <a class="link" href="overload5.html#boost_asio.reference.connect.overload5.exceptions">Exceptions</a> |
| </h6> |
| <div class="variablelist"> |
| <p class="title"><b></b></p> |
| <dl> |
| <dt><span class="term">boost::system::system_error</span></dt> |
| <dd><p> |
| Thrown on failure. If the sequence is empty, the associated <code class="computeroutput"><span class="identifier">error_code</span></code> is <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">error</span><span class="special">::</span><span class="identifier">not_found</span></code>. |
| Otherwise, contains the error from the last connection attempt. |
| </p></dd> |
| </dl> |
| </div> |
| <a name="boost_asio.reference.connect.overload5.remarks"></a><h6> |
| <a name="boost_asio.reference.connect.overload5.remarks-heading"></a> |
| <a class="link" href="overload5.html#boost_asio.reference.connect.overload5.remarks">Remarks</a> |
| </h6> |
| <p> |
| This overload assumes that a default constructed object of type <code class="computeroutput"><span class="identifier">Iterator</span></code> represents the end of the sequence. |
| This is a valid assumption for iterator types such as <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</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">resolver</span><span class="special">::</span><span class="identifier">iterator</span></code>. |
| </p> |
| <a name="boost_asio.reference.connect.overload5.example"></a><h6> |
| <a name="boost_asio.reference.connect.overload5.example-heading"></a> |
| <a class="link" href="overload5.html#boost_asio.reference.connect.overload5.example">Example</a> |
| </h6> |
| <p> |
| The following connect condition function object can be used to output information |
| about the individual connection attempts: |
| </p> |
| <pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">my_connect_condition</span> |
| <span class="special">{</span> |
| <span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">></span> |
| <span class="identifier">Iterator</span> <span class="keyword">operator</span><span class="special">()(</span> |
| <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">ec</span><span class="special">,</span> |
| <span class="identifier">Iterator</span> <span class="identifier">next</span><span class="special">)</span> |
| <span class="special">{</span> |
| <span class="keyword">if</span> <span class="special">(</span><span class="identifier">ec</span><span class="special">)</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"Error: "</span> <span class="special"><<</span> <span class="identifier">ec</span><span class="special">.</span><span class="identifier">message</span><span class="special">()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"Trying: "</span> <span class="special"><<</span> <span class="identifier">next</span><span class="special">-></span><span class="identifier">endpoint</span><span class="special">()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="keyword">return</span> <span class="identifier">next</span><span class="special">;</span> |
| <span class="special">}</span> |
| <span class="special">};</span> |
| </pre> |
| <p> |
| It would be used with the <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">connect</span></code> |
| function as follows: |
| </p> |
| <pre class="programlisting"><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">resolver</span> <span class="identifier">r</span><span class="special">(</span><span class="identifier">io_service</span><span class="special">);</span> |
| <span class="identifier">tcp</span><span class="special">::</span><span class="identifier">resolver</span><span class="special">::</span><span class="identifier">query</span> <span class="identifier">q</span><span class="special">(</span><span class="string">"host"</span><span class="special">,</span> <span class="string">"service"</span><span class="special">);</span> |
| <span class="identifier">tcp</span><span class="special">::</span><span class="identifier">socket</span> <span class="identifier">s</span><span class="special">(</span><span class="identifier">io_service</span><span class="special">);</span> |
| <span class="identifier">tcp</span><span class="special">::</span><span class="identifier">resolver</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">i</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">connect</span><span class="special">(</span> |
| <span class="identifier">s</span><span class="special">,</span> <span class="identifier">r</span><span class="special">.</span><span class="identifier">resolve</span><span class="special">(</span><span class="identifier">q</span><span class="special">),</span> <span class="identifier">my_connect_condition</span><span class="special">());</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"Connected to: "</span> <span class="special"><<</span> <span class="identifier">i</span><span class="special">-></span><span class="identifier">endpoint</span><span class="special">()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| </pre> |
| </div> |
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| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2003-2011 Christopher |
| M. Kohlhoff<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) |
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