<span class="keyword">struct</span> <a class="link" href="extract_or_throw.html" title="Struct template extract_or_throw">extract_or_throw</a> <span class="special">{</span>
<span class="special">}</span><span class="special">;</span></pre></div>
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-<a name="idm46436917522592"></a><h2>Description</h2>
+<a name="idm45554749014800"></a><h2>Description</h2>
<p>The metafunction results in a type that is in form of <code class="computeroutput">T const&</code>, if <code class="computeroutput">T</code> is not an MPL type sequence, or <code class="computeroutput">value_ref< T, TagT ></code> otherwise. In the latter case the value reference shall never be empty. </p>
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