title: array indexing (converting to integer) with scoped enumeration
body: <p>C++11 scoped enumerators (<code>enum class</code> syntax) do not convert to integers so they cannot be used directly as array indexes.</p>
  
  <p>What's the best way to get the benefit of scoping when using them in this fashion?</p>
  
  <p>I've provided a couple answers, but please add more ideas!</p>