title: using comparison function in stl container
body: <p>Why can I do this:</p>
  
  <pre><code>stable_sort(it1, it2, binary_function);
  </code></pre>
  
  <p>but not this:</p>
  
  <pre><code>priority_queue&lt;type, vector&lt;type&gt;, binary_function&gt; pq;
  </code></pre>
  
  <p>Why can I use a function in the first case, but need an object in the second?</p>