// In header: <boost/accumulators/statistics/weighted_sum.hpp>

template<typename Sample, typename Weight, typename Tag> 
struct weighted_sum_impl {
  // types
  typedef numeric::functional::multiplies< Sample, Weight >::result_type weighted_sample;
  typedef weighted_sample                                                result_type;    

  // construct/copy/destruct
  template<typename Args> weighted_sum_impl(Args const &);

  // public member functions
  template<typename Args> void operator()(Args const &);
  result_type result(dont_care) const;
};