title: Template class methods definition with enable_if as template parameter
body: <p>I asked <a href="https://stackoverflow.com/q/9652531/368599">this question</a> earlier where <a href="https://stackoverflow.com/a/9652733/368599">a solution</a> was presented. The solution is great as far as the question is concerned, but now I am confused on how I would define the methods <em>outside</em> of the class i.e. I would like to define the methods in an <code>.inl</code> file. What would be the syntax in this case?</p>
  
  <p>Just to be clear, for a template class, the method definition will be:</p>
  
  <pre><code>template &lt;typename T&gt;
  struct Foo
  {
    Foo();
  };
  
  // C-tor definition
  template &lt;typename T&gt;
  Foo&lt;T&gt;::Foo()
  {
  }
  </code></pre>
  
  <p>How would I define methods for the template class with <code>enable_if</code> as one of the parameters?</p>
  
  <pre><code>template &lt;typename Policy, enable_if&lt; is_base&lt;BasePolicy, Policy&gt;::value &gt;::type &gt;
  struct Foo
  {
    Foo();
  };
  
  // C-tor definition -- ???
  </code></pre>