class person_t
{
public:
    person_t(const std::string& name, size_t age)
        : name_(name), age_(age){}

    template<typename Visitor>
    void accept(Visitor& v) {v.visit(*this);}
    size_t age() const {return age_;}
private:
    std::string name_;
    size_t age_;
};

struct person_visitor_t
{
    person_visitor_t(size_t age_limit) : age_limit_(age_limit){}
    bool operator()(const person_t& p) {return visit(p);}
    bool visit(const person_t& p) {return p.age() < age_limit_;}
    size_t age_limit_;
};

struct person_visitor_t
{
    person_visitor_t(size_t age_limit) : age_limit_(age_limit){}
    bool operator()(const person_t& p) {return p.age() < age_limit_;}
    size_t age_limit_;
};

#include <iostream>

int main()
{
  unsigned char x = 0;
  do
  {
    std::cout << (int)x << std::endl;
    ++x;
  }
  while (x != 0);

  return 0;
}