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| <h2><span class="refentrytitle">Struct template is_env</span></h2> |
| <p>boost::proto::is_env — A Boolean metafuntion for determining whether or not a type is a Proto |
| transform environment.</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.transform.env_hpp" title="Header <boost/proto/transform/env.hpp>">boost/proto/transform/env.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_env.html" title="Struct template is_env">is_env</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="idp382036288"></a><h2>Description</h2> |
| <p><code class="computeroutput">is_env<T></code> inherits from <code class="computeroutput">mpl::true_</code> under the following |
| conditions: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> |
| <li class="listitem">If <code class="computeroutput">T</code> is <a class="link" href="empty_env.html" title="Struct empty_env">proto::empty_env</a>.</li> |
| <li class="listitem">If <code class="computeroutput">T</code> is a specialization of <a class="link" href="env.html" title="Struct template env">proto::env<></a>.</li> |
| <li class="listitem">If <code class="computeroutput">T</code> is derived from any of the above.</li> |
| <li class="listitem">If <code class="computeroutput">T</code> is a cv-qualified variant of any of the above.</li> |
| <li class="listitem">If <code class="computeroutput">T</code> is a reference to any of the above.</li> |
| </ul></div> |
| <p> |
| </p> |
| <p>Otherwise, <code class="computeroutput">is_env<T></code> inherits from <code class="computeroutput">mpl::false_</code>. |
| </p> |
| </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>) |
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