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<div class="refentry">
<a name="boost.signalN"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2><span class="refentrytitle">Class template signalN</span></h2>
<p>boost::signalN — Set of safe multicast callback types.</p>
</div>
<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="../signals/reference.html#header.boost.signal_hpp" title="Header <boost/signal.hpp>">boost/signal.hpp</a>>
</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> R<span class="special">,</span> <span class="keyword">typename</span> T1<span class="special">,</span> <span class="keyword">typename</span> T2<span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="keyword">typename</span> TN<span class="special">,</span>
<span class="keyword">typename</span> Combiner <span class="special">=</span> <a class="link" href="last_value.html" title="Class template last_value">last_value</a><span class="special"><</span><span class="identifier">R</span><span class="special">></span><span class="special">,</span> <span class="keyword">typename</span> Group <span class="special">=</span> <span class="keyword">int</span><span class="special">,</span>
<span class="keyword">typename</span> GroupCompare <span class="special">=</span> std::less<span class="special"><</span><span class="identifier">Group</span><span class="special">></span><span class="special">,</span>
<span class="keyword">typename</span> SlotFunction <span class="special">=</span> <a class="link" href="functionN.html" title="Class template functionN">functionN</a><span class="special"><</span><span class="identifier">R</span><span class="special">,</span> <span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">TN</span><span class="special">></span> <span class="special">></span>
<span class="keyword">class</span> <a class="link" href="signalN.html" title="Class template signalN">signalN</a> <span class="special">:</span> <span class="keyword">public</span> <a class="link" href="signals/trackable.html" title="Class trackable">signals::trackable</a>,
<span class="keyword">private</span> noncopyable <span class="comment">// Exposition only</span>
<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="keyword">typename</span> <span class="identifier">Combiner</span><span class="special">::</span><span class="identifier">result_type</span> <a name="boost.signalN.result_type"></a><span class="identifier">result_type</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">Combiner</span> <a name="boost.signalN.combiner_type"></a><span class="identifier">combiner_type</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">Group</span> <a name="boost.signalN.group_type"></a><span class="identifier">group_type</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">GroupCompare</span> <a name="boost.signalN.group_compare_type"></a><span class="identifier">group_compare_type</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">SlotFunction</span> <a name="boost.signalN.slot_function_type"></a><span class="identifier">slot_function_type</span><span class="special">;</span>
<span class="keyword">typedef</span> <a class="link" href="slot.html" title="Class template slot">slot</a><span class="special"><</span><span class="identifier">SlotFunction</span><span class="special">></span> <a name="boost.signalN.slot_type"></a><span class="identifier">slot_type</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">unspecified</span></em></span> <a name="boost.signalN.slot_result_type"></a><span class="identifier">slot_result_type</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">unspecified</span></em></span> <a name="boost.signalN.slot_call_iterator"></a><span class="identifier">slot_call_iterator</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">T1</span> <a name="boost.signalN.argument_type"></a><span class="identifier">argument_type</span><span class="special">;</span> <span class="comment">// If N == 1</span>
<span class="keyword">typedef</span> <span class="identifier">T1</span> <a name="boost.signalN.first_argument_type"></a><span class="identifier">first_argument_type</span><span class="special">;</span> <span class="comment">// If N == 2</span>
<span class="keyword">typedef</span> <span class="identifier">T2</span> <a name="boost.signalN.second_argument_type"></a><span class="identifier">second_argument_type</span><span class="special">;</span> <span class="comment">// If N == 2</span>
<span class="keyword">typedef</span> <span class="identifier">T1</span> <a name="boost.signalN.arg1_type"></a><span class="identifier">arg1_type</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">T2</span> <a name="boost.signalN.arg2_type"></a><span class="identifier">arg2_type</span><span class="special">;</span>
.
.
.
<span class="keyword">typedef</span> <span class="identifier">TN</span> <a name="boost.signalN.argN_type"></a><span class="identifier">argN_type</span><span class="special">;</span>
<span class="comment">// static constants</span>
<span class="keyword">static</span> <span class="keyword">const</span> <span class="keyword">int</span> <span class="identifier">arity</span> = <span class="identifier">N</span><span class="special">;</span>
<span class="comment">// <a class="link" href="signalN.html#boost.signalNconstruct-copy-destruct">construct/copy/destruct</a></span>
<a class="link" href="signalN.html#id-1_3_36_5_1_1_2_22-bb"><span class="identifier">signalN</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">combiner_type</span><span class="special">&</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="keyword">const</span> <span class="identifier">group_compare_type</span><span class="special">&</span> <span class="special">=</span> <span class="identifier">group_compare_type</span><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span>
<a class="link" href="signalN.html#id-1_3_36_5_1_1_2_23-bb"><span class="special">~</span><span class="identifier">signalN</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
<span class="comment">// <a class="link" href="signalN.html#id-1_3_36_5_1_1_2_24-bb">connection management</a></span>
<a class="link" href="signals/connection.html" title="Class connection">signals::connection</a>
<a class="link" href="signalN.html#id-1_3_36_5_1_1_2_24_1_1-bb"><span class="identifier">connect</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">slot_type</span><span class="special">&</span><span class="special">,</span> <span class="identifier">signals</span><span class="special">::</span><span class="identifier">connect_position</span> <span class="special">=</span> <span class="identifier">signals</span><span class="special">::</span><span class="identifier">at_back</span><span class="special">)</span><span class="special">;</span>
<a class="link" href="signals/connection.html" title="Class connection">signals::connection</a>
<a class="link" href="signalN.html#id-1_3_36_5_1_1_2_24_1_2-bb"><span class="identifier">connect</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">group_type</span><span class="special">&</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">slot_type</span><span class="special">&</span><span class="special">,</span>
<span class="identifier">signals</span><span class="special">::</span><span class="identifier">connect_position</span> <span class="special">=</span> <span class="identifier">signals</span><span class="special">::</span><span class="identifier">at_back</span><span class="special">)</span><span class="special">;</span>
<span class="keyword">void</span> <a class="link" href="signalN.html#id-1_3_36_5_1_1_2_24_2_1-bb"><span class="identifier">disconnect</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">group_type</span><span class="special">&</span><span class="special">)</span><span class="special">;</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Slot<span class="special">></span> <span class="keyword">void</span> <a class="link" href="signalN.html#id-1_3_36_5_1_1_2_24_2_2-bb"><span class="identifier">disconnect</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">Slot</span><span class="special">&</span><span class="special">)</span><span class="special">;</span>
<span class="keyword">void</span> <a class="link" href="signalN.html#id-1_3_36_5_1_1_2_24_3-bb"><span class="identifier">disconnect_all_slots</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
<span class="keyword">bool</span> <a class="link" href="signalN.html#id-1_3_36_5_1_1_2_24_4-bb"><span class="identifier">empty</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <a class="link" href="signalN.html#id-1_3_36_5_1_1_2_24_5-bb"><span class="identifier">num_slots</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="comment">// <a class="link" href="signalN.html#id-1_3_36_5_1_1_2_25-bb">invocation</a></span>
<span class="identifier">result_type</span> <a class="link" href="signalN.html#id-1_3_36_5_1_1_2_25_1_1-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">arg1_type</span><span class="special">,</span> <span class="identifier">arg2_type</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">argN_type</span><span class="special">)</span><span class="special">;</span>
<span class="identifier">result_type</span> <a class="link" href="signalN.html#id-1_3_36_5_1_1_2_25_1_2-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">arg1_type</span><span class="special">,</span> <span class="identifier">arg2_type</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">argN_type</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="comment">// <a class="link" href="signalN.html#id-1_3_36_5_1_1_2_26-bb">combiner access</a></span>
<span class="identifier">combiner_type</span><span class="special">&</span> <a class="link" href="signalN.html#id-1_3_36_5_1_1_2_26_1_1-bb"><span class="identifier">combiner</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
<span class="keyword">const</span> <span class="identifier">combiner_type</span><span class="special">&</span> <a class="link" href="signalN.html#id-1_3_36_5_1_1_2_26_1_2-bb"><span class="identifier">combiner</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="special">}</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="id-1.3.36.5.2.3.4"></a><h2>Description</h2>
<p>The class template <a class="link" href="signalN.html" title="Class template signalN">signalN</a> covers
several related classes signal0, signal1, signal2, etc.,
where the number suffix describes the number of function
parameters the signal and its connected slots will
take. Instead of enumerating all classes, a single pattern
<a class="link" href="signalN.html" title="Class template signalN">signalN</a> will be described, where N
represents the number of function parameters.</p>
<div class="refsect2">
<a name="id-1.3.36.5.2.3.4.3"></a><h3>
<a name="boost.signalNconstruct-copy-destruct"></a><code class="computeroutput">signalN</code>
public
construct/copy/destruct</h3>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
<pre class="literallayout"><a name="id-1_3_36_5_1_1_2_22-bb"></a><span class="identifier">signalN</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">combiner_type</span><span class="special">&</span> combiner <span class="special">=</span> <span class="identifier">combiner_type</span><span class="special">(</span><span class="special">)</span><span class="special">,</span>
<span class="keyword">const</span> <span class="identifier">group_compare_type</span><span class="special">&</span> compare <span class="special">=</span> <span class="identifier">group_compare_type</span><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span></pre>
<div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">Effects:</span></p></td>
<td>Initializes the signal to contain no slots, copies the given combiner into internal storage, and stores the given group comparison function object to compare groups.</td>
</tr>
<tr>
<td><p><span class="term">Postconditions:</span></p></td>
<td><code class="computeroutput">this-><a class="link" href="signalN.html#id-1_3_36_5_1_1_2_24_4-bb">empty</a>()</code></td>
</tr>
</tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><a name="id-1_3_36_5_1_1_2_23-bb"></a><span class="special">~</span><span class="identifier">signalN</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
<div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term">Effects:</span></p></td>
<td>Disconnects all slots connected to <code class="computeroutput">*this</code>.</td>
</tr></tbody>
</table></div>
</li>
</ol></div>
</div>
<div class="refsect2">
<a name="id-1.3.36.5.2.3.4.4"></a><h3>
<a name="id-1_3_36_5_1_1_2_24-bb"></a><code class="computeroutput">signalN</code> connection management</h3>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
<pre class="literallayout"><a name="id-1_3_36_5_1_1_2_24_1-bb"></a><a class="link" href="signals/connection.html" title="Class connection">signals::connection</a>
<a name="id-1_3_36_5_1_1_2_24_1_1-bb"></a><span class="identifier">connect</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">slot_type</span><span class="special">&</span> slot<span class="special">,</span>
<span class="identifier">signals</span><span class="special">::</span><span class="identifier">connect_position</span> at <span class="special">=</span> <span class="identifier">signals</span><span class="special">::</span><span class="identifier">at_back</span><span class="special">)</span><span class="special">;</span>
<a class="link" href="signals/connection.html" title="Class connection">signals::connection</a>
<a name="id-1_3_36_5_1_1_2_24_1_2-bb"></a><span class="identifier">connect</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">group_type</span><span class="special">&</span> group<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">slot_type</span><span class="special">&</span> slot<span class="special">,</span>
<span class="identifier">signals</span><span class="special">::</span><span class="identifier">connect_position</span> at <span class="special">=</span> <span class="identifier">signals</span><span class="special">::</span><span class="identifier">at_back</span><span class="special">)</span><span class="special">;</span></pre>
<div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">Effects:</span></p></td>
<td>Connects the signal this to the incoming
slot. If the slot is inactive, i.e., any of the trackable
objects bound by the slot call have been destroyed, then the
call to connect is a no-op. If the second version of
<code class="computeroutput">connect</code> is invoked, the
slot is associated with the given group. The <code class="computeroutput">at</code>
parameter specifies where the slot should be connected:
<code class="computeroutput">at_front</code> indicates that the slot will be
connected at the front of the list or group of slots and
<code class="computeroutput">at_back</code> indicates that the slot will be
connected at the back of the list or group of
slots.</td>
</tr>
<tr>
<td><p><span class="term">Returns:</span></p></td>
<td>A
<code class="computeroutput"><a class="link" href="signals/connection.html" title="Class connection">signals::connection</a></code>
object that references the newly-created connection between
the signal and the slot; if the slot is inactive, returns a
disconnected connection.</td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td>This routine meets the strong exception guarantee,
where any exception thrown will cause the slot to not be
connected to the signal.</td>
</tr>
<tr>
<td><p><span class="term">Complexity:</span></p></td>
<td>Constant time when connecting a slot
without a group name or logarithmic in the number of groups
when connecting to a particular
group.</td>
</tr>
<tr>
<td><p><span class="term">Notes:</span></p></td>
<td>It is unspecified whether connecting a slot while the
signal is calling will result in the slot being called
immediately.</td>
</tr>
</tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><a name="id-1_3_36_5_1_1_2_24_2-bb"></a><span class="keyword">void</span> <a name="id-1_3_36_5_1_1_2_24_2_1-bb"></a><span class="identifier">disconnect</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">group_type</span><span class="special">&</span> group<span class="special">)</span><span class="special">;</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Slot<span class="special">></span> <span class="keyword">void</span> <a name="id-1_3_36_5_1_1_2_24_2_2-bb"></a><span class="identifier">disconnect</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">Slot</span><span class="special">&</span> slot<span class="special">)</span><span class="special">;</span></pre>
<div class="variablelist"><table border="0" class="variablelist compact">
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<td><p><span class="term">Effects:</span></p></td>
<td>If the parameter is (convertible to) a
group name, any slots in the given group are
disconnected. Otherwise, any slots equal to the given slot
are disconnected.</td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td>Will not throw unless a user destructor or
equality operator <code class="computeroutput">==</code> throws. If either throws,
not all slots may be disconnected.</td>
</tr>
<tr>
<td><p><span class="term">Complexity:</span></p></td>
<td>If a group is given, O(lg g) + k where
g is the number of groups in the signal and k is the
number of slots in the group. Otherwise, linear in the
number of slots connected to the
signal.</td>
</tr>
</tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><span class="keyword">void</span> <a name="id-1_3_36_5_1_1_2_24_3-bb"></a><span class="identifier">disconnect_all_slots</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
<div class="variablelist"><table border="0" class="variablelist compact">
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<td><p><span class="term">Effects:</span></p></td>
<td>Disconnects all slots connected to the signal.</td>
</tr>
<tr>
<td><p><span class="term">Postconditions:</span></p></td>
<td>
<code class="computeroutput">this-><a class="link" href="signalN.html#id-1_3_36_5_1_1_2_24_4-bb">empty</a>()</code>.</td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td>If disconnecting a slot causes an exception to be
thrown, not all slots may be disconnected.</td>
</tr>
<tr>
<td><p><span class="term">Complexity:</span></p></td>
<td>Linear in the number of slots known to the
signal.</td>
</tr>
<tr>
<td><p><span class="term">Notes:</span></p></td>
<td>May be called at any time within the lifetime of the
signal, including during calls to the signal's slots.</td>
</tr>
</tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><span class="keyword">bool</span> <a name="id-1_3_36_5_1_1_2_24_4-bb"></a><span class="identifier">empty</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
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<td><p><span class="term">Returns:</span></p></td>
<td>
<code class="computeroutput">true</code> if no slots
are connected to the signal, and
<code class="computeroutput">false</code> otherwise.</td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td>Will not throw.</td>
</tr>
<tr>
<td><p><span class="term">Complexity:</span></p></td>
<td>Linear in the number of slots known to the
signal.</td>
</tr>
<tr>
<td><p><span class="term">Rationale:</span></p></td>
<td>Slots can disconnect at any point in time,
including while those same slots are being invoked. It is
therefore possible that the implementation must search
through a list of disconnected slots to determine if any
slots are still connected.</td>
</tr>
</tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <a name="id-1_3_36_5_1_1_2_24_5-bb"></a><span class="identifier">num_slots</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
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<td><p><span class="term">Returns:</span></p></td>
<td>The number of slots connected to the signal</td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td>Will not throw.</td>
</tr>
<tr>
<td><p><span class="term">Complexity:</span></p></td>
<td>Linear in the number of slots known to the
signal.</td>
</tr>
<tr>
<td><p><span class="term">Rationale:</span></p></td>
<td>Slots can disconnect at any point in time,
including while those same slots are being invoked. It is
therefore possible that the implementation must search
through a list of disconnected slots to determine how many
slots are still connected.</td>
</tr>
</tbody>
</table></div>
</li>
</ol></div>
</div>
<div class="refsect2">
<a name="id-1.3.36.5.2.3.4.5"></a><h3>
<a name="id-1_3_36_5_1_1_2_25-bb"></a><code class="computeroutput">signalN</code> invocation</h3>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<pre class="literallayout"><a name="id-1_3_36_5_1_1_2_25_1-bb"></a><span class="identifier">result_type</span> <a name="id-1_3_36_5_1_1_2_25_1_1-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="identifier">arg1_type</span> a1<span class="special">,</span> <span class="identifier">arg2_type</span> a2<span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">argN_type</span> aN<span class="special">)</span><span class="special">;</span>
<span class="identifier">result_type</span> <a name="id-1_3_36_5_1_1_2_25_1_2-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="identifier">arg1_type</span> a1<span class="special">,</span> <span class="identifier">arg2_type</span> a2<span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">argN_type</span> aN<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
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<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">Effects:</span></p></td>
<td>Invokes the combiner with a
<code class="computeroutput">slot_call_iterator</code> range
[first, last) corresponding to the sequence of calls to the
slots connected to signal
<code class="computeroutput">*this</code>. Dereferencing an
iterator in this range causes a slot call with the given set
of parameters <code class="computeroutput">(a1, a2, ...,
aN)</code>, the result of which is returned from
the iterator dereference operation.</td>
</tr>
<tr>
<td><p><span class="term">Returns:</span></p></td>
<td>The result returned by the combiner.</td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td>If an exception is thrown by a slot call, or if the
combiner does not dereference any slot past some given slot,
all slots after that slot in the internal list of connected
slots will not be invoked.</td>
</tr>
<tr>
<td><p><span class="term">Notes:</span></p></td>
<td>
<p class="simpara">Only the slots associated with iterators that are
actually dereferenced will be invoked. Multiple dereferences
of the same iterator will not result in multiple slot
invocations, because the return value of the slot will be
cached.</p>
<p class="simpara">The <code class="computeroutput">const</code> version of
the function call operator will invoke the combiner as
<code class="computeroutput">const</code>, whereas the
non-<code class="computeroutput">const</code> version will
invoke the combiner as
non-<code class="computeroutput">const</code>.</p>
<p class="simpara">Calling the function call operator may invoke undefined
behavior if no slots are connected to the signal, depending
on the combiner used. The default combiner is well-defined
for zero slots when the return type is void but is undefined
when the return type is any other type (because there is no
way to synthesize a return value).</p>
</td>
</tr>
</tbody>
</table></div>
</li></ol></div>
</div>
<div class="refsect2">
<a name="id-1.3.36.5.2.3.4.6"></a><h3>
<a name="id-1_3_36_5_1_1_2_26-bb"></a><code class="computeroutput">signalN</code> combiner access</h3>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<pre class="literallayout"><a name="id-1_3_36_5_1_1_2_26_1-bb"></a><span class="identifier">combiner_type</span><span class="special">&</span> <a name="id-1_3_36_5_1_1_2_26_1_1-bb"></a><span class="identifier">combiner</span><span class="special">(</span><span class="special">)</span><span class="special">;</span>
<span class="keyword">const</span> <span class="identifier">combiner_type</span><span class="special">&</span> <a name="id-1_3_36_5_1_1_2_26_1_2-bb"></a><span class="identifier">combiner</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
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<col align="left" valign="top">
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<td><p><span class="term">Returns:</span></p></td>
<td>A reference to the stored combiner.</td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td>Will not throw.</td>
</tr>
</tbody>
</table></div>
</li></ol></div>
</div>
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2001-2004 Douglas Gregor<p>Use, modification and distribution is subject to 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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