using namespace fmt=boost::format;

   struct timeval tv;
   gettimeofday(&tv, NULL);

   // formatter with default context (no context spec)
   // this means you can't do -- fmt("%{i}",x) for i->[0,n) where x={x0..xn} (data memebers)
   fmt::formatter default_fmt;

   // (x) (y)
   std::cout
      << default_fmt("(%d) (%d)", tv.tv_sec, tv.tv_usec) 
      << std::endl;

   // (x seconds) (y microseconds)
   std::cout
      << default_fmt("(%d) (%d)", 
            fmt::unit<fmt::sec>(tv.tv_sec), 
            fmt::unit<fmt::usec>(tv.tv_usec)) 
      << std::endl;

   // (x sec) (y usec)
   std::cout
      << default_fmt("(%d) (%d)", 
            fmt::unit<fmt::sec,fmt::abbrev>(tv.tv_sec),
            fmt::unit<fmt::usec,fmt::abbrev>(tv.tv_usec)) 
      << std::endl;

   // (x s) (y usec)
   std::cout
      << default_fmt("(%d) (%d)", 
            fmt::unit<fmt::sec,fmt::abbrev_c<1> >(tv.tv_sec),
            fmt::unit<fmt::usec,fmt::abbrev>(tv.tv_usec)) 
      << std::endl;

   typedef fmt::context_adapter<
      timeval,
      fmt::context_spec<
         fmt::context_element<int timeval::*>, //timeval::*>,
         fmt::context_element<int timeval::*>
      > > timeval_context_t;

   fmt::basic_formatter<timeval_context_t> timeval_fmt(&timeval::tv_sec, &timeval::tv_usec);

   // Output the first, then the second context elements
   std::cout << timeval_fmt("%{1}:%{2}",tv) << std::endl;

   typedef fmt::context_adapter<
      timeval,
      fmt::context_spec<
         fmt::context_element<'s', int timeval::*>, //timeval::*>,
         fmt::context_element<'u', int timeval::*>
      > > custom_code_timeval_context_t;

   fmt::basic_formatter<custom_code_timeval_context_t> custom_fmt(&timeval::tv_sec, &timeval::tv_usec);

   // Output tv_sec then tv_usec
   std::cout << custom_fmt("%s:%u",tv) << std::endl;

   fmt::basic_formatter<custom_code_timeval_context_t> custom_fmt_units(
		   fmt::unit<fmt::sec>(&timeval::tv_sec),
		   fmt::unit<fmt::usec>(&timeval::tv_usec));

   // Output "(x seconds) (y microseconds)" for tv_sec=x, tv_usec=y
   std::cout << custom_fmt("(%s) (%u)",tv) << std::endl;