title: Template parameter constraints
body: <p>I've been reading through <a href="http://www2.research.att.com/~bs/bs_faq2.html#constraints" rel="nofollow noreferrer">this advice about template parameter constraints</a> and was confused by this line:</p>
  
  <pre><code>template&lt;class T&gt; class Container : Derived_from&lt;T,Mybase&gt; {
      // ...
  };
  </code></pre>
  
  <p>What's going on here?  Is this just plain old inheritance being used to make the compiler examine <code>Derived_from</code> to perform the desired check?  Why does this not lead to code being generated for <code>Derived_from</code>?</p>
  
  <p>Thanks.</p>