title: can we do deep tie with a c++1y std::tie() -like function?
body: <p>Is there a way to write a variant of <code>std::tie</code> in c++11/1y that ties deeply into a tuple. That is, one in which  <code>tie((x,y),z) = make_tuple(make_tuple(1,2),3)</code> binds <code>x, y, z</code> to <code>1, 2 and 3</code>, respectively as in the following example. It would be nice. Thanks.</p>
  
  <pre><code>#include &lt;tuple&gt;
  #include &lt;iostream&gt;
  using namespace std;
  
  int main() {
    int x, y ,z;
    auto t = make_tuple(1,2);
    std::tie(y,x)= t;
    //std::tie((x,y),z) = make_tuple(t,3); //not working
    cout &lt;&lt; x &lt;&lt; y &lt;&lt; z &lt;&lt; endl;
    return 0;
  }
  </code></pre>