n header: &lt;<a class="link" href="../../attributes.html#header.boost.log.attributes.value_extraction_hpp" title="Header &lt;boost/log/attributes/value_extraction.hpp&gt;">boost/log/attributes/value_extraction.hpp</a>&gt;

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<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> DescriptorT<span class="special">,</span> <span class="keyword">template</span><span class="special">&lt;</span> <span class="keyword">typename</span> <span class="special"