title: Enable template only for some std::vector<T2> type
body: <p>I would to make a template match only for <code>T=std::vector&lt;T2&gt;</code> arguments (<code>T2</code> is an arbitrary type). I can use <code>boost::enable_if</code> in template arguments. How do I test whether a type <code>T</code> is a <code>std::vector</code>?</p>
  
  <p>I could include <code>T::iterator</code> in my template so that non-container types would lead to substitution failure and would not be considered (SFINAE). This way though, any containers which define <code>T::iterator</code> would match, not only <code>std::vector&lt;T2&gt;</code>.</p>