template<typename T>
class comment
{
public:
     comment(const T& _T):m_T(_T)
     {
     }
     ~comment()
     {
     }
     template<typename U>
     friend std::ostream& operator<<(std::ostream& os, const comment<U>& cmnt);
private:
     /*typename*/ const T& m_T;
};

template<typename T>
std::ostream& operator<<(std::ostream& os, const comment<T>& cmnt)
{
     return os << "// " << cmnt.m_T;
}

template<typename T>
class comment;

template<typename T>
std::ostream& operator<<(std::ostream& os, const comment<T>& cmnt);

template<typename T>
class comment
{
public:
     comment(const T& _T):m_T(_T)
     {
     }
     ~comment()
     {
     }
     friend std::ostream& operator<< <T>(std::ostream& os, const comment<T>& cmnt);
private:
     /*typename*/ const T& m_T;
};

template<typename T>
std::ostream& operator<<(std::ostream& os, const comment<T>& cmnt)
{
     return os << "// " << cmnt.m_T;
}