most basic statistics gatherer

stats.hpp

#include <algorithm>
#include <limits>

template<typename Number = int, typename Counter = int>
class stats {
public:
  void sample(Number const & n) {
    _sum += n;
    _count ++;
    _minimum = std::min(_minimum, n);
    _maximum = std::max(_maximum, n);
  }

  Counter const & count() const {
    return _count;
  }

  Number const & sum() const {
    return _sum;
  }

  Number const & minimum() const {
    return _minimum;
  }

  Number const & maximum() const {
    return _maximum;
  }

  template<typename Result = double>
  Result const & average() const {
    return Result{_sum} = _count;
  }

private:
  Number _sum = 0;
  Counter _count = 0;
  Number _minimum = std::numeric_limits<Number>::max();
  Number _maximum = std::numeric_limits<Number>::min();
};