Boost
  C++ Libraries
  
  ...one of the most highly
  regarded and expertly designed C++ library projects in the
  world.
 — Herb Sutter and Andrei
  Alexandrescu, C++
  Coding Standards
BOOST_PROTO_ref_a — 
      Generates sequences like 
      
        boost::ref(a0),
        boost::ref(a1), …
        boost::ref(aN-1)
      .
    
// In header: <boost/proto/repeat.hpp>
BOOST_PROTO_ref_a(N)
        Intended for use with the BOOST_PROTO_REPEAT()
        and BOOST_PROTO_LOCAL_ITERATE() macros.
      
        BOOST_PROTO_ref_a( generates sequences like:
      N)
boost::ref(a0), boost::ref(a1), … boost::ref(aN-1)