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<header name="boost/signals2/signal.hpp" last-revision="$Date: 2007-03-06 16:51:55 -0500 (Tue, 06 Mar 2007) $">
  <using-namespace name="boost::signals2"/>
  <using-namespace name="boost"/>
  <namespace name="boost">
    <namespace name="signals2">
      <enum name="connect_position">
        <enumvalue name="at_front"/>
        <enumvalue name="at_back"/>
      </enum>
      <class name="signal">
        <template>
          <template-type-parameter name="Signature">
            <purpose>Function type R (T1, T2, ..., TN)</purpose>
          </template-type-parameter>
          <template-type-parameter name="Combiner">
            <default><classname>boost::signals2::optional_last_value</classname>&lt;R&gt;</default>
          </template-type-parameter>
          <template-type-parameter name="Group">
            <default>int</default>
          </template-type-parameter>
          <template-type-parameter name="GroupCompare">
            <default><classname>std::less</classname>&lt;Group&gt;</default>
          </template-type-parameter>
          <template-type-parameter name="SlotFunction">
            <default><classname>boost::function</classname>&lt;Signature&gt;</default>
          </template-type-parameter>
          <template-type-parameter name="ExtendedSlotFunction">
            <default><classname>boost::function</classname>&lt;R (const <classname alt="signals2::connection">connection</classname> &amp;, T1, T2, ..., TN)&gt;</default>
          </template-type-parameter>
          <template-type-parameter name="Mutex">
            <default><classname>boost::signals2::mutex</classname></default>
          </template-type-parameter>
        </template>
        <inherit access="public">
          <type><classname>boost::signals2::signal_base</classname></type>
        </inherit>

        <purpose>Safe multicast callback.</purpose>

        <description>
          <para>
            See the <link linkend="signals2.tutorial">tutorial</link>
            for more information on how to use the signal class.
          </para>
        </description>

        <typedef name="signature_type"><type>Signature</type></typedef>
        <typedef name="result_type">
          <type>typename Combiner::result_type</type>
        </typedef>
        <typedef name="combiner_type"><type>Combiner</type></typedef>
        <typedef name="group_type"><type>Group</type></typedef>
        <typedef name="group_compare_type"><type>GroupCompare</type></typedef>
        <typedef name="slot_function_type"><type>SlotFunction</type></typedef>
        <typedef name="slot_type">
          <type>typename <classname>signals2::slot</classname>&lt;Signature, SlotFunction&gt;</type>
        </typedef>
        <typedef name="extended_slot_function_type"><type>ExtendedSlotFunction</type></typedef>
        <typedef name="extended_slot_type">
          <type>typename <classname>signals2::slot</classname>&lt;R (const <classname alt="signals2::connection">connection</classname> &amp;, T1, ..., TN), ExtendedSlotFunction&gt;</type>
          <description>
            <para>Slots of the <code>extended_slot_type</code> may be connected to the signal using the
              <methodname>connect_extended</methodname> methods.  The <code>extended_slot_type</code>
              has an additional <classname>signals2::connection</classname> argument in its signature,
              which gives slot functions access to their connection to the signal
              invoking them.
            </para>
          </description>
        </typedef>
        <typedef name="slot_result_type">
          <type>typename SlotFunction::result_type</type>
          <description>
            <para>
              This is the type returned when dereferencing the input iterators passed to the signal's
              combiner.
            </para>
          </description>
        </typedef>
        <typedef name="slot_call_iterator">
          <type><emphasis>unspecified</emphasis></type>
          <description>
            <para>
              The input iterator type passed to the combiner when the signal is invoked.
            </para>
          </description>
        </typedef>
        <typedef name="argument_type">
          <type>T1</type>
          <purpose>Exists iff arity == 1</purpose>
        </typedef>
        <typedef name="first_argument_type">
          <type>T1</type>
          <purpose>Exists iff arity == 2</purpose>
        </typedef>
        <typedef name="second_argument_type">
          <type>T2</type>
          <purpose>Exists iff arity == 2</purpose>
        </typedef>

        <class name="arg">
          <template>
            <template-nontype-parameter name="n">
              <type>unsigned</type>
            </template-nontype-parameter>
          </template>
          <typedef name="type">
            <type>Tn</type>
            <purpose>The type of the <classname alt="signals2::signal">signal</classname>'s (n+1)th argument</purpose>
          </typedef>
        </class>

        <static-constant name="arity">
          <type>int</type>
          <default>N</default>
          <purpose>The number of arguments taken by the signal.</purpose>
        </static-constant>

        <constructor>
          <parameter name="combiner">
            <paramtype>const combiner_type&amp;</paramtype>
            <default>combiner_type()</default>
          </parameter>
          <parameter name="compare">
            <paramtype>const group_compare_type&amp;</paramtype>
            <default>group_compare_type()</default>
          </parameter>

          <effects><para>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.</para></effects>

          <postconditions><para><computeroutput>this-&gt;<methodname>empty</methodname>()</computeroutput></para></postconditions>
        </constructor>

        <constructor>
          <parameter name="other">
            <paramtype>signal &amp;&amp;</paramtype>
          </parameter>
          <description><para>Move constructor.</para></description>
          <postconditions><para><computeroutput>other.<methodname>null</methodname>()</computeroutput></para></postconditions>

          <throws><para>Will not throw.</para></throws>
        </constructor>

        <copy-assignment>
          <parameter name="rhs">
            <paramtype>signal &amp;&amp;</paramtype>
          </parameter>
          <description><para>Move assignment.</para></description>
          <postconditions><para><computeroutput>rhs.<methodname>null</methodname>()</computeroutput></para></postconditions>

          <throws><para>Will not throw.</para></throws>
        </copy-assignment>

        <method-group name="connection management">
          <overloaded-method name="connect">
            <signature>
              <type><classname alt="signals2::connection">connection</classname></type>
              <parameter name="slot">
                <paramtype>const slot_type&amp;</paramtype>
              </parameter>
              <parameter name="at">
                <paramtype>connect_position</paramtype>
                <default>at_back</default>
              </parameter>
            </signature>

            <signature>
              <type><classname alt="signals2::connection">connection</classname></type>
              <parameter name="group">
                <paramtype>const group_type&amp;</paramtype>
              </parameter>
              <parameter name="slot">
                <paramtype>const slot_type&amp;</paramtype>
              </parameter>
              <parameter name="at">
                <paramtype>connect_position</paramtype>
                <default>at_back</default>
              </parameter>
            </signature>

            <effects><para>Connects the signal this to the incoming
            slot. If the slot is inactive, i.e., any of the slots's tracked
            objects have been destroyed, then the
            call to connect is a no-op. If the second version of
            <computeroutput>connect</computeroutput> is invoked, the
            slot is associated with the given group. The <code>at</code>
            parameter specifies where the slot should be connected:
            <code>at_front</code> indicates that the slot will be
            connected at the front of the list or group of slots and
            <code>at_back</code> indicates that the slot will be
            connected at the back of the list or group of
            slots.</para></effects>

            <returns><para>A
            <computeroutput><classname>signals2::connection</classname></computeroutput>
            object that references the newly-created connection between
            the signal and the slot; if the slot is inactive, returns a
            disconnected connection.</para></returns>

            <throws><para>This routine meets the strong exception guarantee,
            where any exception thrown will cause the slot to not be
            connected to the signal.</para></throws>

            <complexity><para>Constant time when connecting a slot
            without a group name or logarithmic in the number of groups
            when connecting to a particular
            group.</para></complexity>

            <notes><para>It is unspecified whether connecting a slot while the
            signal is calling will result in the slot being called
            immediately.</para></notes>
          </overloaded-method>
          <overloaded-method name="connect_extended">
            <signature>
              <type><classname alt="signals2::connection">connection</classname></type>
              <parameter name="slot">
                <paramtype>const extended_slot_type&amp;</paramtype>
              </parameter>
              <parameter name="at">
                <paramtype>connect_position</paramtype>
                <default>at_back</default>
              </parameter>
            </signature>

            <signature>
              <type><classname alt="signals2::connection">connection</classname></type>
              <parameter name="group">
                <paramtype>const group_type&amp;</paramtype>
              </parameter>
              <parameter name="slot">
                <paramtype>const extended_slot_type&amp;</paramtype>
              </parameter>
              <parameter name="at">
                <paramtype>connect_position</paramtype>
                <default>at_back</default>
              </parameter>
            </signature>
            <description>
              <para>
                The <code>connect_extended</code> methods work the same as the <methodname>connect</methodname>
                methods, except they take slots of type <classname>extended_slot_type</classname>.
                This is useful if a slot needs to access the connection between it and the
                signal invoking it, for example if it wishes to disconnect or block its own connection.
              </para>
            </description>
          </overloaded-method>

          <overloaded-method name="disconnect">
            <signature>
              <type>void</type>
              <parameter name="group">
                <paramtype>const group_type&amp;</paramtype>
              </parameter>
            </signature>
            <signature>
              <template>
                <template-type-parameter name="S"/>
              </template>
              <type>void</type>
              <parameter name="slot_func">
                <paramtype>const S&amp;</paramtype>
              </parameter>
            </signature>

            <effects><para>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 function
            are disconnected.
            </para>
            <para>Note, the <code>slot_func</code>
            argument should not be an actual <classname>signals2::slot</classname>
            object (which does not even support <code>operator==</code>), but rather
            the functor you wrapped inside a <classname>signals2::slot</classname>
            when you initially made the connection.
            </para></effects>

            <throws><para>Will not throw unless a user destructor or
            equality operator <code>==</code> throws. If either throws,
            not all slots may be disconnected.</para></throws>

            <complexity><para>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.</para></complexity>
          </overloaded-method>

          <method name="disconnect_all_slots">
            <type>void</type>
            <effects><para>Disconnects all slots connected to the signal.</para></effects>

            <postconditions><para><computeroutput>this-&gt;<methodname>empty</methodname>()</computeroutput>.</para></postconditions>

            <throws><para>If disconnecting a slot causes an exception to be
            thrown, not all slots may be disconnected.</para></throws>

            <complexity><para>Linear in the number of slots known to the
            signal.</para></complexity>

            <notes><para>May be called at any time within the lifetime of the
            signal, including during calls to the signal's slots.</para></notes>
          </method>

          <method name="empty" cv="const">
            <type>bool</type>
            <returns><para><computeroutput>true</computeroutput> if no slots
            are connected to the signal, and
            <computeroutput>false</computeroutput> otherwise.</para></returns>

            <throws><para>Will not throw.</para></throws>

            <complexity><para>Linear in the number of slots known to the
            signal.</para></complexity>

            <rationale><para>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.</para></rationale>
          </method>

          <method name="num_slots" cv="const">
            <type>std::size_t</type>
            <returns><para>The number of slots connected to the signal</para></returns>

            <throws><para>Will not throw.</para></throws>

            <complexity><para>Linear in the number of slots known to the
            signal.</para></complexity>

            <rationale><para>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.</para></rationale>
          </method>
        </method-group>

        <method-group name="invocation">
          <overloaded-method name="operator()">
            <signature>
              <type>result_type</type>
              <parameter name="a1"><paramtype>arg&lt;0&gt;::type</paramtype></parameter>
              <parameter name="a2"><paramtype>arg&lt;1&gt;::type</paramtype></parameter>
              <parameter><paramtype>...</paramtype></parameter>
              <parameter name="aN"><paramtype>arg&lt;N-1&gt;::type</paramtype></parameter>
            </signature>

            <signature cv="const">
              <type>result_type</type>
              <parameter name="a1"><paramtype>arg&lt;0&gt;::type</paramtype></parameter>
              <parameter name="a2"><paramtype>arg&lt;1&gt;::type</paramtype></parameter>
              <parameter><paramtype>...</paramtype></parameter>
              <parameter name="aN"><paramtype>arg&lt;N-1&gt;::type</paramtype></parameter>
            </signature>

            <effects><para>Invokes the combiner with a
            <computeroutput>slot_call_iterator</computeroutput> range
            [first, last) corresponding to the sequence of calls to the
            slots connected to signal
            <computeroutput>*this</computeroutput>. Dereferencing an
            iterator in this range causes a slot call with the given set
            of parameters <computeroutput>(a1, a2, ...,
            aN)</computeroutput>, the result of which is returned from
            the iterator dereference operation.</para></effects>

            <returns><para>The result returned by the combiner.</para></returns>

            <throws><para>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.</para></throws>

            <notes><para>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.</para>

            <para>The <computeroutput>const</computeroutput> version of
            the function call operator will invoke the combiner as
            <computeroutput>const</computeroutput>, whereas the
            non-<computeroutput>const</computeroutput> version will
            invoke the combiner as
            non-<computeroutput>const</computeroutput>.</para>
            </notes>
          </overloaded-method>
        </method-group>

        <method-group name="combiner access">
          <method name="combiner" cv="const">
            <type>combiner_type</type>

            <returns><para>A copy of the stored combiner.</para></returns>
            <throws><para>Will not throw.</para></throws>
          </method>
          <method name="set_combiner">
            <type>void</type>
            <parameter name="combiner"><paramtype>const combiner_type&amp;</paramtype></parameter>

            <effects><para>Copies a new combiner into the signal for use with
            future signal invocations.</para></effects>
            <throws><para>Will not throw.</para></throws>
          </method>
        </method-group>

        <method-group name="modifiers">
          <method name="swap">
            <type>void</type>
            <parameter name="other">
              <paramtype><classname alt="signals2::signal">signal</classname>&amp;</paramtype>
            </parameter>
            <effects><para>Swaps the signal referenced in
            <computeroutput>this</computeroutput> and
            <computeroutput>other</computeroutput>.</para></effects>

            <throws><para>Will not throw.</para></throws>
          </method>
        </method-group>
    
        <method-group name="misc">
          <method name="null" cv="const">
            <type>bool</type>
            <returns><para><computeroutput>false</computeroutput> for a normal signal,
                <computeroutput>true</computeroutput> after a signal
                has been moved from.  Null signals are nonfunctional husks left
                behind after a signal is moved.  They may not be invoked or have
                slots connected to them.</para>
            </returns>

            <throws><para>Will not throw.</para></throws>

            <notes>
                <para>A null signal may be destroyed, swapped, or move assigned.  Also,
                    the following methods may be called on a null signal:
                </para>
                <variablelist>
                    <varlistentry><term><methodname>disconnect</methodname> and <methodname>disconnect_all_slots</methodname></term>
                        <listitem>no effect</listitem>
                    </varlistentry>
                    <varlistentry><term><methodname>empty</methodname></term>
                        <listitem>returns <computeroutput>true</computeroutput></listitem>
                    </varlistentry>
                    <varlistentry><term><methodname>null</methodname></term>
                        <listitem>returns <computeroutput>true</computeroutput></listitem>
                    </varlistentry>
                    <varlistentry><term><methodname>num_slots</methodname></term>
                        <listitem>returns <computeroutput>0</computeroutput></listitem>
                    </varlistentry>
                </variablelist>
                <para>Any other operation on a null signal is invalid.</para>
            </notes>
          </method>
        </method-group>

        <free-function-group name="specialized algorithms">
          <function name="swap">
            <template>
              <template-type-parameter name="Signature"/>
              <template-type-parameter name="Combiner"/>
              <template-type-parameter name="Group"/>
              <template-type-parameter name="GroupCompare"/>
              <template-type-parameter name="SlotFunction"/>
              <template-type-parameter name="ExtendedSlotFunction"/>
              <template-type-parameter name="Mutex"/>
            </template>
            <type>void</type>
            <parameter name="x">
              <paramtype><classname alt="signals2::signal">signal</classname>&lt;Signature, Combiner, Group, GroupCompare, SlotFunction, ExtendedSlotFunction, Mutex&gt;&amp;</paramtype>
            </parameter>
            <parameter name="y">
              <paramtype><classname alt="signals2::signal">signal</classname>&lt;Signature, Combiner, Group, GroupCompare, SlotFunction, ExtendedSlotFunction, Mutex&gt;&amp;</paramtype>
            </parameter>

            <effects><para><computeroutput>x.swap(y)</computeroutput></para></effects>
            <throws><para>Will not throw.</para></throws>
          </function>
        </free-function-group>
      </class>
    </namespace>
  </namespace>
</header>
