title: Passing partially specialized template as a template parameter
body: <p>I have a class template, expecting some other template as a parameter:</p>
  
  <pre><code>template&lt;
      class Key, 
      template &lt;typename K,template &lt;typename T&gt; class Allocator&gt; class Policy
  &gt;
  class container {
       Policy&lt;Key,Allocator&gt;* _policy;
       //some code here
  };
  </code></pre>
  
  <p>and usually i use it with the policy class like this:</p>
  
  <pre><code>template &lt;class Key,template &lt;typename T&gt; class Allocator&gt; class policy {
      //some code
  };
  </code></pre>
  
  <p>but what if i have to pass additional template parameter to policy class? Something like:</p>
  
  <pre><code>template &lt;time_t Age,class Key,template &lt;typename T&gt; class Allocator&gt; class policy_3 {
      //some code
  };
  </code></pre>
  
  <p>What can i do, to allow users of that class, pass the Age paratemeter without touching others? For example:</p>
  
  <pre><code>typedef container&lt;key_type,policy_3&lt;100500&gt; &gt; containerWithAge;
  </code></pre>