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| <a name="boost.signals2.signal_type"></a><div class="titlepage"></div> |
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| <h2><span class="refentrytitle">Class template signal_type</span></h2> |
| <p>boost::signals2::signal_type — Specify a the template type parameters of a <a class="link" href="signal.html" title="Class template signal">boost::signals2::signal</a> using named parameters.</p> |
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| <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> |
| <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../signals2/reference.html#header.boost.signals2.signal_type_hpp" title="Header <boost/signals2/signal_type.hpp>">boost/signals2/signal_type.hpp</a>> |
| |
| </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A0<span class="special">,</span> <span class="keyword">typename</span> A1 <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">parameter</span><span class="special">::</span><span class="identifier">void_</span><span class="special">,</span> |
| <span class="keyword">typename</span> A2 <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">parameter</span><span class="special">::</span><span class="identifier">void_</span><span class="special">,</span> |
| <span class="keyword">typename</span> A3 <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">parameter</span><span class="special">::</span><span class="identifier">void_</span><span class="special">,</span> |
| <span class="keyword">typename</span> A4 <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">parameter</span><span class="special">::</span><span class="identifier">void_</span><span class="special">,</span> |
| <span class="keyword">typename</span> A5 <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">parameter</span><span class="special">::</span><span class="identifier">void_</span><span class="special">,</span> |
| <span class="keyword">typename</span> A6 <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">parameter</span><span class="special">::</span><span class="identifier">void_</span><span class="special">></span> |
| <span class="keyword">class</span> <a class="link" href="signal_type.html" title="Class template signal_type">signal_type</a> <span class="special">{</span> |
| <span class="keyword">public</span><span class="special">:</span> |
| <span class="comment">// types</span> |
| <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">detail</span></em></span> <a name="boost.signals2.signal_type.signature_type"></a><span class="identifier">signature_type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">detail</span></em></span> <a name="boost.signals2.signal_type.combiner_type"></a><span class="identifier">combiner_type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">detail</span></em></span> <a name="boost.signals2.signal_type.group_type"></a><span class="identifier">group_type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">detail</span></em></span> <a name="boost.signals2.signal_type.group_compare_type"></a><span class="identifier">group_compare_type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">detail</span></em></span> <a name="boost.signals2.signal_type.slot_function_type"></a><span class="identifier">slot_function_type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">detail</span></em></span> <a name="boost.signals2.signal_type.extended_slot_function__id324622"></a><span class="identifier">extended_slot_function_type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">implementation</span><span class="special">-</span><span class="identifier">detail</span></em></span> <a name="boost.signals2.signal_type.mutex_type"></a><span class="identifier">mutex_type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">signal</span><span class="special"><</span><span class="identifier">signature_type</span><span class="special">,</span> <span class="identifier">combiner_type</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">mutex_type</span><span class="special">></span> <a name="boost.signals2.signal_type.type"></a><span class="identifier">type</span><span class="special">;</span> |
| <span class="special">}</span><span class="special">;</span></pre></div> |
| <div class="refsect1"> |
| <a name="id2558944"></a><h2>Description</h2> |
| <p>The <code class="computeroutput">signal_type</code> metafunction employs the Boost.Parameter library to |
| allow users to specify the template type parameters of a <a class="link" href="signal.html" title="Class template signal">signals2::signal</a> |
| using named parameters. The resulting signal type is provided through the |
| <code class="computeroutput">signal_type::type</code> typedef. Named template type parameters |
| can enhance readability of code, and provide convenience for specifying classes |
| which have a large number of template parameters. |
| </p> |
| <p>The template type parameters may be passed positionally, similarly to passing them |
| to the <a class="link" href="signal.html" title="Class template signal">signals2::signal</a> class directly. Or, they may be passed as named template parameters |
| by wrapping them in one of the template keyword classes provided in the |
| <code class="computeroutput">boost::signals2::keywords</code> namespace. The supported template keywords are: |
| <a class="link" href="keywords/signature_type.html" title="Class template signature_type">keywords::signature_type</a>, <a class="link" href="keywords/combiner_type.html" title="Class template combiner_type">keywords::combiner_type</a>, |
| <a class="link" href="keywords/group_type.html" title="Class template group_type">keywords::group_type</a>, <a class="link" href="keywords/group_compare_type.html" title="Class template group_compare_type">keywords::group_compare_type</a>, |
| <a class="link" href="keywords/slot_function_type.html" title="Class template slot_function_type">keywords::slot_function_type</a>, <a class="link" href="keywords/extended_slot_function__id650460.html" title="Class template extended_slot_function_type">keywords::extended_slot_function_type</a>, |
| and <a class="link" href="keywords/mutex_type.html" title="Class template mutex_type">keywords::mutex_type</a>. |
| </p> |
| <p>The default types for unspecified template type parameters are the same as those for the |
| <a class="link" href="../signal.html" title="Class template signal">signal</a> class. |
| </p> |
| <p> |
| Named template type parameters are especially convenient when you only wish to change a |
| few of a signal's template type parameters from their defaults, and the parameters |
| you wish to change are near the end of the signal's template parameter list. |
| For example, if you only wish to change the <code class="computeroutput">Mutex</code> template type |
| parameter of a signal, you might write: |
| </p> |
| <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">bs2</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">signals2</span><span class="special">;</span> |
| <span class="keyword">using</span> <span class="identifier">bs2</span><span class="special">::</span><span class="identifier">keywords</span><span class="special">;</span> |
| <span class="identifier">bs2</span><span class="special">::</span><span class="identifier">signal_type</span><span class="special"><</span><span class="keyword">void</span> <span class="special">(</span><span class="special">)</span><span class="special">,</span> <span class="identifier">mutex_type</span><span class="special"><</span><span class="identifier">bs2</span><span class="special">::</span><span class="identifier">dummy_mutex</span><span class="special">></span> <span class="special">></span><span class="special">::</span><span class="identifier">type</span> <span class="identifier">sig</span><span class="special">;</span> |
| </pre> |
| <p>For comparison, to specify the same type using the signal class directly looks like:</p> |
| <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">bs2</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">signals2</span><span class="special">;</span> |
| <span class="identifier">bs2</span><span class="special">::</span><span class="identifier">signal</span> |
| <span class="special"><</span> |
| <span class="keyword">void</span> <span class="special">(</span><span class="special">)</span><span class="special">,</span> |
| <span class="identifier">bs2</span><span class="special">::</span><span class="identifier">optional_last_value</span><span class="special"><</span><span class="keyword">void</span><span class="special">></span><span class="special">,</span> |
| <span class="keyword">int</span><span class="special">,</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">less</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span><span class="special">,</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">function</span><span class="special"><</span><span class="keyword">void</span> <span class="special">(</span><span class="special">)</span><span class="special">></span><span class="special">,</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">function</span><span class="special"><</span><span class="keyword">void</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">connection</span> <span class="special">&</span><span class="special">)</span><span class="special">></span><span class="special">,</span> |
| <span class="identifier">bs2</span><span class="special">::</span><span class="identifier">dummy_mutex</span> |
| <span class="special">></span> <span class="identifier">sig</span><span class="special">;</span> |
| </pre> |
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| <td align="right"><div class="copyright-footer">Copyright © 2001-2004 Douglas Gregor<br>Copyright © 2007-2009 Frank Mori Hess<p>Distributed under the Boost |
| Software License, Version 1.0. (See accompanying file |
| <code class="filename">LICENSE_1_0.txt</code> or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</p> |
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