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| <a name="boost.proto.is_transform"></a><div class="titlepage"></div> |
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| <h2><span class="refentrytitle">Struct template is_transform</span></h2> |
| <p>boost::proto::is_transform — Boolean metafunction which tells whether a type is a |
| <a class="link" href="../../PrimitiveTransform.html" title="Concept PrimitiveTransform">PrimitiveTransform</a> or not.</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.traits_hpp" title="Header <boost/proto/traits.hpp>">boost/proto/traits.hpp</a>> |
| |
| </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> |
| <span class="keyword">struct</span> <a class="link" href="is_transform.html" title="Struct template is_transform">is_transform</a> <span class="special">:</span> <span class="keyword"></span> mpl::bool_<<em class="replaceable"><code>true-or-false</code></em>> <span class="special">{</span> |
| <span class="special">}</span><span class="special">;</span></pre></div> |
| <div class="refsect1"> |
| <a name="idp375488272"></a><h2>Description</h2> |
| <p> |
| <code class="computeroutput">proto::is_transform<></code> is used by the |
| <code class="computeroutput"><a class="link" href="make.html" title="Struct template make">proto::make<></a></code> |
| transform to determine whether a type <code class="computeroutput">R</code> represents a |
| <a class="link" href="../../PrimitiveTransform.html" title="Concept PrimitiveTransform">PrimitiveTransform</a> to apply, or whether it merely represents itself. |
| </p> |
| <p> |
| It is also used by the |
| <code class="computeroutput"><a class="link" href="call.html" title="Struct template call">proto::call<></a></code> |
| transform to determine whether the function types <code class="computeroutput">R()</code>, |
| <code class="computeroutput">R(A1)</code>, and <code class="computeroutput">R(A1, A2)</code> should |
| be passed the expression, state and data parameters (as needed). |
| </p> |
| <p> |
| Unless specialized for a type |
| <code class="computeroutput">T</code>, <code class="computeroutput">proto::is_transform<T>::value</code> |
| is computed as follows: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> |
| <li class="listitem"><p> |
| If <code class="computeroutput">T</code> is a class type that inherits directly or indirectly from |
| an instantiation of |
| <code class="computeroutput"><a class="link" href="transform.html" title="Struct template transform">proto::transform<></a></code>, |
| <code class="computeroutput">proto::is_transform<T>::value</code> is <code class="computeroutput">true</code>. |
| </p></li> |
| <li class="listitem"><p> |
| Otherwise, <code class="computeroutput">proto::is_transform<T>::value</code> |
| is <code class="computeroutput">false</code>. |
| </p></li> |
| </ul></div> |
| <p> |
| </p> |
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| <td align="left"></td> |
| <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>) |
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