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<div class="refentry">
<a name="boost.proto.extends"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2><span class="refentrytitle">Struct template extends</span></h2>
<p>boost::proto::extends — For adding behaviors to a Proto expression template.</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="../../proto/reference.html#header.boost.proto.extends_hpp" title="Header <boost/proto/extends.hpp>">boost/proto/extends.hpp</a>>
</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <a class="link" href="../../Expr.html" title="Concept Expr">Expr</a><span class="special">,</span> <span class="keyword">typename</span> Derived<span class="special">,</span>
<span class="keyword">typename</span> <a class="link" href="../../Domain.html" title="Concept Domain">Domain</a> <span class="special">=</span> <a class="link" href="default_domain.html" title="Struct default_domain">proto::default_domain</a><span class="special">></span>
<span class="keyword">struct</span> <a class="link" href="extends.html" title="Struct template extends">extends</a> <span class="special">{</span>
<span class="comment">// types</span>
<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Expr</span><span class="special">::</span><span class="identifier">proto_base_expr</span> <a name="boost.proto.extends.proto_base_expr"></a><span class="identifier">proto_base_expr</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">Domain</span> <a name="boost.proto.extends.proto_domain"></a><span class="identifier">proto_domain</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">Derived</span> <a name="boost.proto.extends.proto_derived_expr"></a><span class="identifier">proto_derived_expr</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">extends</span> <a name="boost.proto.extends.proto_extends"></a><span class="identifier">proto_extends</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">proto_base_expr</span><span class="special">::</span><span class="identifier">proto_tag</span> <a name="boost.proto.extends.proto_tag"></a><span class="identifier">proto_tag</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">proto_base_expr</span><span class="special">::</span><span class="identifier">proto_args</span> <a name="boost.proto.extends.proto_args"></a><span class="identifier">proto_args</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">proto_base_expr</span><span class="special">::</span><span class="identifier">proto_arity</span> <a name="boost.proto.extends.proto_arity"></a><span class="identifier">proto_arity</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">proto_base_expr</span><span class="special">::</span><span class="identifier">proto_grammar</span> <a name="boost.proto.extends.proto_grammar"></a><span class="identifier">proto_grammar</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">proto_base_expr</span><span class="special">::</span><span class="identifier">proto_child</span><em class="replaceable"><code><span class="identifier">N</span></code></em> <a name="boost.proto.extends.proto_childN"></a><span class="identifier">proto_childN</span><span class="special">;</span> <span class="comment">// For each <em class="replaceable"><code>N</code></em> in <em class="replaceable"><code>[0,max(1,proto_arity_c))</code></em></span>
<span class="comment">// member classes/structs/unions</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Signature<span class="special">></span>
<span class="keyword">struct</span> <a class="link" href="extends/result.html" title="Struct template result">result</a> <span class="special">{</span>
<span class="comment">// types</span>
<span class="keyword">typedef</span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a class="link" href="extends/result.html#boost.proto.extends.result.type"><span class="identifier">type</span></a><span class="special">;</span>
<span class="special">}</span><span class="special">;</span>
<span class="comment">// <a class="link" href="extends.html#boost.proto.extendsconstruct-copy-destruct">construct/copy/destruct</a></span>
<a class="link" href="extends.html#idm45506996287312-bb"><span class="identifier">extends</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
<a class="link" href="extends.html#idm45506996287024-bb"><span class="identifier">extends</span></a><span class="special">(</span><a class="link" href="extends.html" title="Struct template extends">extends</a> <span class="keyword">const</span> <span class="special">&</span><span class="special">)</span><span class="special">;</span>
<a class="link" href="extends.html#idm45506996285120-bb"><span class="identifier">extends</span></a><span class="special">(</span><span class="identifier">Expr</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">)</span><span class="special">;</span>
<span class="comment">// <a class="link" href="extends.html#idm45506996283504-bb">public static functions</a></span>
<span class="keyword">static</span> <span class="identifier">Derived</span> <span class="keyword">const</span> <a class="link" href="extends.html#idm45506996282944-bb"><span class="identifier">make</span></a><span class="special">(</span><span class="identifier">Expr</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">)</span><span class="special">;</span>
<span class="comment">// <a class="link" href="extends.html#idm45506996278784-bb">public member functions</a></span>
<span class="identifier">proto_base_expr</span> <span class="special">&</span> <a class="link" href="extends.html#idm45506996277904-bb"><span class="identifier">proto_base</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
<span class="identifier">proto_base_expr</span> <span class="keyword">const</span> <span class="special">&</span> <a class="link" href="extends.html#idm45506996275616-bb"><span class="identifier">proto_base</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a class="link" href="extends.html#idm45506996272736-bb"><span class="keyword">operator</span><span class="special">=</span></a><span class="special">(</span><span class="identifier">A</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> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a class="link" href="extends.html#idm45506996267456-bb"><span class="keyword">operator</span><span class="special">=</span></a><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</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> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a class="link" href="extends.html#idm45506996262912-bb"><span class="keyword">operator</span><span class="special">=</span></a><span class="special">(</span><span class="identifier">A</span> <span class="special">&</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a class="link" href="extends.html#idm45506996258096-bb"><span class="keyword">operator</span><span class="special">=</span></a><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a class="link" href="extends.html#idm45506975961184-bb"><span class="keyword">operator</span><span class="special">[</span><span class="special">]</span></a><span class="special">(</span><span class="identifier">A</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> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a class="link" href="extends.html#idm45506975956016-bb"><span class="keyword">operator</span><span class="special">[</span><span class="special">]</span></a><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</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> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a class="link" href="extends.html#idm45506975951472-bb"><span class="keyword">operator</span><span class="special">[</span><span class="special">]</span></a><span class="special">(</span><span class="identifier">A</span> <span class="special">&</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a class="link" href="extends.html#idm45506975946656-bb"><span class="keyword">operator</span><span class="special">[</span><span class="special">]</span></a><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span><span class="special">...</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a class="link" href="extends.html#idm45506975941520-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&</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><span class="special">...</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a class="link" href="extends.html#idm45506975935664-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">...</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
<span class="comment">// public data members</span>
<span class="identifier">Expr</span> <span class="identifier">proto_expr_</span><span class="special">;</span> <span class="comment">// For exposition only.</span>
<span class="keyword">static</span> <span class="keyword">const</span> <span class="keyword">long</span> <span class="identifier">proto_arity_c</span><span class="special">;</span> <span class="comment">// <code class="computeroutput">= proto_base_expr::proto_arity_c;</code></span>
<span class="special">}</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="idm45555190978128"></a><h2>Description</h2>
<p>
Use <code class="computeroutput">proto::extends<></code> to give expressions in your
domain custom data members and member functions.
</p>
<p>
Conceptually, using <code class="computeroutput">proto::extends<></code> is akin
to inheriting from <code class="computeroutput"><a class="link" href="expr.html" title="Struct template expr">proto::expr</a><></code>
and adding your own members. Using <code class="computeroutput">proto::extends<></code> is
generally preferrable to straight inheritance because the members that would be inherited from
<code class="computeroutput"><a class="link" href="expr.html" title="Struct template expr">proto::expr</a><></code> would
be wrong; they would incorrectly slice off your additional members when building
larger expressions from smaller ones. <code class="computeroutput">proto::extends<></code>
automatically gives your expression types the appropriate operator overloads that
preserve your domain-specific members when composing expression trees.
</p>
<p>
Expression extensions are typically defined as follows:
</p>
<p>
</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">Expr</span> <span class="special">></span>
<span class="keyword">struct</span> <span class="identifier">my_expr</span>
<span class="special">:</span> <span class="identifier">proto</span><span class="special">::</span><span class="identifier">extends</span><span class="special"><</span>
<span class="identifier">Expr</span> <span class="comment">// The expression type we're extending</span>
<span class="special">,</span> <span class="identifier">my_expr</span><span class="special"><</span> <span class="identifier">Expr</span> <span class="special">></span> <span class="comment">// The type we're defining</span>
<span class="special">,</span> <span class="identifier">my_domain</span> <span class="comment">// The domain associated with this expression extension</span>
<span class="special">></span>
<span class="special">{</span>
<span class="comment">// An expression extension is constructed from the expression</span>
<span class="comment">// it is extending.</span>
<span class="identifier">my_expr</span><span class="special">(</span> <span class="identifier">Expr</span> <span class="keyword">const</span> <span class="special">&</span> <span class="identifier">e</span> <span class="special">=</span> <span class="identifier">Expr</span><span class="special">(</span><span class="special">)</span> <span class="special">)</span>
<span class="special">:</span> <span class="identifier">my_expr</span><span class="special">::</span><span class="identifier">proto_extends</span><span class="special">(</span> <span class="identifier">e</span> <span class="special">)</span>
<span class="special">{</span><span class="special">}</span>
<span class="comment">// Unhide proto::extends::operator=</span>
<span class="comment">// (This is only necessary if a lazy assignment operator</span>
<span class="comment">// makes sense for your domain-specific language.)</span>
<span class="identifier">BOOST_PROTO_EXTENDS_USING_ASSIGN</span><span class="special">(</span><span class="identifier">my_expr</span><span class="special">)</span>
<span class="comment">/*
... domain-specific members go here ...
*/</span>
<span class="special">}</span><span class="special">;</span></pre>
<p>
</p>
<p>
See also:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><code class="computeroutput"><a class="link" href="../../BOOST_PROTO_EXTENDS.html" title="Macro BOOST_PROTO_EXTENDS">BOOST_PROTO_EXTENDS</a>()</code></li>
<li class="listitem"><code class="computeroutput"><a class="link" href="../../BOOST_PROTO_EXTENDS_USING_ASSIGN.html" title="Macro BOOST_PROTO_EXTENDS_USING_ASSIGN">BOOST_PROTO_EXTENDS_USING_ASSIGN</a>()</code></li>
<li class="listitem"><code class="computeroutput"><a class="link" href="../../BOOST_PROTO_EXTENDS_USING_ASSIGN_NON_DEPENDENT.html" title="Macro BOOST_PROTO_EXTENDS_USING_ASSIGN_NON_DEPENDENT">BOOST_PROTO_EXTENDS_USING_ASSIGN_NON_DEPENDENT</a>()</code></li>
</ul></div>
<p>
</p>
<div class="refsect2">
<a name="idm45555190926368"></a><h3>
<a name="boost.proto.extendsconstruct-copy-destruct"></a><code class="computeroutput">extends</code>
public
construct/copy/destruct</h3>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem"><pre class="literallayout"><a name="idm45506996287312-bb"></a><span class="identifier">extends</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre></li>
<li class="listitem"><pre class="literallayout"><a name="idm45506996287024-bb"></a><span class="identifier">extends</span><span class="special">(</span><a class="link" href="extends.html" title="Struct template extends">extends</a> <span class="keyword">const</span> <span class="special">&</span> that<span class="special">)</span><span class="special">;</span></pre></li>
<li class="listitem"><pre class="literallayout"><a name="idm45506996285120-bb"></a><span class="identifier">extends</span><span class="special">(</span><span class="identifier">Expr</span> <span class="keyword">const</span> <span class="special">&</span> expr_<span class="special">)</span><span class="special">;</span></pre></li>
</ol></div>
</div>
<div class="refsect2">
<a name="idm45555190909056"></a><h3>
<a name="idm45506996283504-bb"></a><code class="computeroutput">extends</code> public static functions</h3>
<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
<pre class="literallayout"><span class="keyword">static</span> <span class="identifier">Derived</span> <span class="keyword">const</span> <a name="idm45506996282944-bb"></a><span class="identifier">make</span><span class="special">(</span><span class="identifier">Expr</span> <span class="keyword">const</span> <span class="special">&</span> expr<span class="special">)</span><span class="special">;</span></pre>
<p>Construct an expression extension from the base expression.</p>
</li></ol></div>
</div>
<div class="refsect2">
<a name="idm45555190898704"></a><h3>
<a name="idm45506996278784-bb"></a><code class="computeroutput">extends</code> public member functions</h3>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
<pre class="literallayout"><span class="identifier">proto_base_expr</span> <span class="special">&</span> <a name="idm45506996277904-bb"></a><span class="identifier">proto_base</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">Returns:</span></p></td>
<td><code class="computeroutput">proto_expr_.proto_base()</code></td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td>Will not throw.</td>
</tr>
</tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><span class="identifier">proto_base_expr</span> <span class="keyword">const</span> <span class="special">&</span> <a name="idm45506996275616-bb"></a><span class="identifier">proto_base</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</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">Returns:</span></p></td>
<td><code class="computeroutput">proto_expr_.proto_base()</code></td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td>Will not throw.</td>
</tr>
</tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a name="idm45506996272736-bb"></a><span class="keyword">operator</span><span class="special">=</span><span class="special">(</span><span class="identifier">A</span> <span class="special">&</span> a<span class="special">)</span><span class="special">;</span></pre>
<p>Lazy assignment expression</p>
<div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term">Returns:</span></p></td>
<td><p>A new expression node representing the assignment operation.</p></td>
</tr></tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a name="idm45506996267456-bb"></a><span class="keyword">operator</span><span class="special">=</span><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&</span> a<span class="special">)</span><span class="special">;</span></pre>
<p>
This is an overloaded member function, provided for convenience. It differs from
the above function only in what argument(s) it accepts.
</p>
</li>
<li class="listitem">
<pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a name="idm45506996262912-bb"></a><span class="keyword">operator</span><span class="special">=</span><span class="special">(</span><span class="identifier">A</span> <span class="special">&</span> a<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
<p>
This is an overloaded member function, provided for convenience. It differs from
the above function only in what argument(s) it accepts.
</p>
</li>
<li class="listitem">
<pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a name="idm45506996258096-bb"></a><span class="keyword">operator</span><span class="special">=</span><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&</span> a<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
<p>
This is an overloaded member function, provided for convenience. It differs from
the above function only in what argument(s) it accepts.
</p>
</li>
<li class="listitem">
<pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a name="idm45506975961184-bb"></a><span class="keyword">operator</span><span class="special">[</span><span class="special">]</span><span class="special">(</span><span class="identifier">A</span> <span class="special">&</span> a<span class="special">)</span><span class="special">;</span></pre>
<p>Lazy subscript expression</p>
<div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term">Returns:</span></p></td>
<td><p>A new expression node representing the subscript operation.</p></td>
</tr></tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a name="idm45506975956016-bb"></a><span class="keyword">operator</span><span class="special">[</span><span class="special">]</span><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&</span> a<span class="special">)</span><span class="special">;</span></pre>
<p>
This is an overloaded member function, provided for convenience. It differs from
the above function only in what argument(s) it accepts.
</p>
</li>
<li class="listitem">
<pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a name="idm45506975951472-bb"></a><span class="keyword">operator</span><span class="special">[</span><span class="special">]</span><span class="special">(</span><span class="identifier">A</span> <span class="special">&</span> a<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
<p>
This is an overloaded member function, provided for convenience. It differs from
the above function only in what argument(s) it accepts.
</p>
</li>
<li class="listitem">
<pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a name="idm45506975946656-bb"></a><span class="keyword">operator</span><span class="special">[</span><span class="special">]</span><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&</span> a<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
<p>
This is an overloaded member function, provided for convenience. It differs from
the above function only in what argument(s) it accepts.
</p>
</li>
<li class="listitem">
<pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span><span class="special">...</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a name="idm45506975941520-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">...</span> a<span class="special">)</span><span class="special">;</span></pre>
<p>Lazy function call</p>
<div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term">Returns:</span></p></td>
<td><p>A new expression node representing the function call operation.</p></td>
</tr></tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span><span class="special">...</span> A<span class="special">></span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em> <a name="idm45506975935664-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="identifier">A</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">...</span> a<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
<p>
This is an overloaded member function, provided for convenience. It differs from
the above function only in what argument(s) it accepts.
</p>
</li>
</ol></div>
</div>
</div>
</div>
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<td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<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>)
</p>
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</tr></table>
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