title: std::mem_fun vs std::mem_fn
body: <p>What is the difference between <strong><code>std::mem_fun</code></strong> and <strong><code>std::mem_fn</code></strong>? Why is the naming so confusing?</p>
  
  <p>Boost's <a href="http://www.boost.org/doc/libs/1_50_0/libs/bind/mem_fn.html" rel="noreferrer">documentation</a> says that <code>std::mem_fn</code> can replace <code>std::mem_fun</code> in most cases. So in what situation would you still use <code>std::mem_fun</code>?</p>