title: Constexpr member variables with setters?
body: <p>So on my C++ homework assignment the instructions say.. </p>
  
  <blockquote>
    <p>Create a constexpr member for kUnboundLower and kUnboundUpper.  </p>
    
    <p>...</p>
    
    <p>Create lower bound and upper bound setters and getters.</p>
  </blockquote>
  
  <p>How is this possible? If something is <code>constexpr</code> you can't set it again. What am I missing here?</p>