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  28 <h2><span class="refentrytitle">Macro BOOST_PROTO_EXTENDS_USING_ASSIGN_NON_DEPENDENT</span></h2>
  29 <p>BOOST_PROTO_EXTENDS_USING_ASSIGN_NON_DEPENDENT &#8212; For exposing in classes that inherit from
  30       <code class="computeroutput"><a class="link" href="boost/proto/extends.html" title="Struct template extends">proto::extends&lt;&gt;</a></code>
  31       the overloaded assignment operators defined therein. Unlike the
  32       <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> macro,
  33       <code class="computeroutput">BOOST_PROTO_EXTENDS_USING_ASSIGN_NON_DEPENDENT()</code> is for use in non-dependent
  34       contexts.
  35       </p>
  36 </div>
  37 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  38 <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;
  39
  40 </span>BOOST_PROTO_EXTENDS_USING_ASSIGN_NON_DEPENDENT(Derived)</pre></div>
  41 <div class="refsect1">
  42 <a name="idp371044176"></a><h2>Description</h2>
  43 <p>
  44         The standard usage of
  45         <code class="computeroutput"><a class="link" href="boost/proto/extends.html" title="Struct template extends">proto::extends&lt;&gt;</a></code>
  46         is to define a class template that inherits from it. The derived class template automatically gets a
  47         compiler-generated assignment operator that hides the ones defined in
  48         <code class="computeroutput"><a class="link" href="boost/proto/extends.html" title="Struct template extends">proto::extends&lt;&gt;</a></code>.
  49         Using <code class="computeroutput">BOOST_PROTO_EXTENDS_USING_ASSIGN()</code> in the derived class solves this problem.
  50       </p>
  51 <p>
  52         However, if the expression extension is an ordinary class and not a class template, the usage of
  53         <code class="computeroutput">BOOST_PROTO_EXTENDS_USING_ASSIGN()</code> is in a so-called non-dependent context. In plain English,
  54         it means it is illegal to use <code class="computeroutput">typename</code> in some places where it is required in a class template.
  55         In those cases, you should use <code class="computeroutput">BOOST_PROTO_EXTENDS_USING_ASSIGN_NON_DEPENDENT()</code> instead.
  56       </p>
  57 <p>
  58                 See also:
  59                 </p>
  60 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  61 <li class="listitem"><code class="computeroutput"><a class="link" href="boost/proto/extends.html" title="Struct template extends">proto::extends&lt;&gt;</a></code></li>
  62 <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>
  63 </ul></div>
  64 <p>
  65       </p>
  66 </div>
  67 </div>
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  69 <td align="left"></td>
  70 <td align="right"><div class="copyright-footer">Copyright &#169; 2008 Eric Niebler<p>
  71         Distributed under the Boost Software License, Version 1.0. (See accompanying
  72         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>)
  73       </p>
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