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  29 <h2><span class="refentrytitle">Macro BOOST_PROTO_BASIC_EXTENDS</span></h2>
  30 <p>BOOST_PROTO_BASIC_EXTENDS &#8212; For creating expression wrappers that add members to a Proto expression template, like
  31       <code class="computeroutput"><a class="link" href="boost/proto/extends.html" title="Struct template extends">proto::extends&lt;&gt;</a></code>,
  32       but while retaining POD-ness of the expression wrapper.</p>
  33 </div>
  34 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  35 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="proto/reference.html#header.boost.proto.extends_hpp" title="Header &lt;boost/proto/extends.hpp&gt;">boost/proto/extends.hpp</a>&gt;
  36
  37 </span>BOOST_PROTO_BASIC_EXTENDS(Expr, Derived, Domain)</pre></div>
  38 <div class="refsect1">
  39 <a name="idp463554560"></a><h2>Description</h2>
  40 <p>
  41         <code class="computeroutput">BOOST_PROTO_BASIC_EXTENDS()</code> adds the basic typedefs, member functions, and
  42         data members necessary to make a struct a valid Proto expression extension. It does <span class="emphasis"><em>not</em></span>
  43         add any constructors, virtual functions or access control blocks that would render the containing
  44         struct non-POD.
  45       </p>
  46 <p>
  47         <code class="computeroutput">Expr</code> is the Proto expression that the enclosing struct extends.
  48         <code class="computeroutput">Derived</code> is the type of the enclosing struct.
  49         <code class="computeroutput">Domain</code> is the Proto domain to which this expression extension belongs.
  50         (See <code class="computeroutput"><a class="link" href="boost/proto/domain.html" title="Struct template domain">proto::domain&lt;&gt;</a></code>.)
  51         Can be preceeded with "<code class="computeroutput">typename</code>" if the specified domain is a dependent type.
  52       </p>
  53 <p><code class="computeroutput">BOOST_PROTO_BASIC_EXTENDS()</code> adds to its enclosing struct
  54         exactly one data member of type <code class="computeroutput">Expr</code>.
  55       </p>
  56 <p>If the <code class="computeroutput">Domain</code> parameter is dependent, you can specify it as
  57         <code class="computeroutput">typename Domain</code>, as in
  58         <code class="computeroutput">BOOST_PROTO_BASIC_EXTENDS(Expr, Derived, typename Domain)</code>
  59       </p>
  60 <p>
  61         <span class="bold"><strong>Example:</strong></span></p>
  62 <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span> <span class="keyword">class</span> <span class="identifier">Expr</span> <span class="special">&gt;</span>
  63 <span class="keyword">struct</span> <span class="identifier">my_expr</span><span class="special">;</span>
  64
  65 <span class="keyword">struct</span> <span class="identifier">my_domain</span>
  66   <span class="special">:</span> <a class="link" href="boost/proto/domain.html" title="Struct template domain">proto::domain</a><span class="special">&lt;</span> <a class="link" href="boost/proto/pod_generator.html" title="Struct template pod_generator">proto::pod_generator</a><span class="special">&lt;</span> <span class="identifier">my_expr</span> <span class="special">&gt;</span> <span class="special">&gt;</span>
  67 <span class="special">{</span><span class="special">}</span><span class="special">;</span>
  68
  69 <span class="keyword">template</span><span class="special">&lt;</span> <span class="keyword">class</span> <span class="identifier">Expr</span> <span class="special">&gt;</span>
  70 <span class="keyword">struct</span> <span class="identifier">my_expr</span>
  71 <span class="special">{</span>
  72     <span class="comment">// OK, this makes my_expr&lt;&gt; a valid Proto expression extension.</span>
  73     <span class="comment">// my_expr&lt;&gt; does /not/ have overloaded assignment, subscript,</span>
  74     <span class="comment">// and function call operators that build expression templates, however.</span>
  75     <a class="link" href="BOOST_PROTO_BASIC_EXTENDS.html" title="Macro BOOST_PROTO_BASIC_EXTENDS">BOOST_PROTO_BASIC_EXTENDS</a><span class="special">(</span><span class="identifier">Expr</span><span class="special">,</span> <span class="identifier">my_expr</span><span class="special">,</span> <span class="identifier">my_domain</span><span class="special">)</span>
  76 <span class="special">}</span><span class="special">;</span>
  77
  78 <span class="comment">// OK, my_expr&lt;&gt; is POD, so this is statically initialized:</span>
  79 <span class="identifier">my_expr</span><span class="special">&lt;</span> <a class="link" href="boost/proto/terminal.html" title="Struct template terminal">proto::terminal</a><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span><span class="special">::</span><span class="identifier">type</span> <span class="special">&gt;</span> <span class="keyword">const</span> <span class="identifier">_1</span> <span class="special">=</span> <span class="special">{</span><span class="special">{</span><span class="number">1</span><span class="special">}</span><span class="special">}</span><span class="special">;</span></pre>
  80 <p>
  81       </p>
  82 <p>
  83         See also:
  84         </p>
  85 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  86 <li class="listitem"><code class="computeroutput"><a class="link" href="BOOST_PROTO_EXTENDS_ASSIGN.html" title="Macro BOOST_PROTO_EXTENDS_ASSIGN">BOOST_PROTO_EXTENDS_ASSIGN</a>()</code></li>
  87 <li class="listitem"><code class="computeroutput"><a class="link" href="BOOST_PROTO_EXTENDS_SUBSCRIPT.html" title="Macro BOOST_PROTO_EXTENDS_SUBSCRIPT">BOOST_PROTO_EXTENDS_SUBSCRIPT</a>()</code></li>
  88 <li class="listitem"><code class="computeroutput"><a class="link" href="BOOST_PROTO_EXTENDS_FUNCTION.html" title="Macro BOOST_PROTO_EXTENDS_FUNCTION">BOOST_PROTO_EXTENDS_FUNCTION</a>()</code></li>
  89 <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>
  90 </ul></div>
  91 <p>
  92       </p>
  93 </div>
  94 </div>
  95 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
  96 <td align="left"></td>
  97 <td align="right"><div class="copyright-footer">Copyright &#169; 2008 Eric Niebler<p>
  98         Distributed under the Boost Software License, Version 1.0. (See accompanying
  99         file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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