title: Partial specialization of a nested class
body: <p>How to partially specialize nest<strong>ed</strong> class without partially specializing the nest<strong>ing</strong> class?</p>
  <p>Implementation of <code>class C</code> is the same for all <code>N</code>.</p>
  <p>Implementation of <code>C::iterator</code> is special for <code>N=1</code>.</p>
  <pre><code>template&lt;class T, int N&gt;
  class C
  {
      class iterator;
      ...
  };
  
  template&lt;class T, int N&gt;
  class C&lt;T, N&gt;::iterator
  {
      ...
  };
  
  // Partial specialization doesn't compile:
  template&lt;class T&gt;
  class C&lt;T, 1&gt;::iterator
  {
      ...
  };
  </code></pre>
  <p>I can partially specialize <code>class C</code> for <code>N=1</code>, but that's a lot of code duplication...</p>