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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>
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<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>
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<a name="idp382199632"></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>
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<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>
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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>)
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