title: Count of parameters in a parameter pack? Is there a C++0x std lib function for this?
body: <p>I was just wondering if there was anything in the C++0x std lib already available to count the number of parameters in a parameter pack?  I'd like to get rid of the field_count in the code below.  I know I can build my own counter, but it just seems like this would be an obvious thing to include in the C++0x std lib, and I wanted to be sure it wasn't already there :)  Home-grown counter implementations are most welcome too.</p>
  
  <pre><code>template&lt;const int field_count, typename... Args&gt; struct Entity {
      const tuple&lt;Args...&gt; data;
      const array&lt;const char*, field_count&gt; source_names;
  
      Entity() : data() {
      }
  };
  </code></pre>