strongtypedef.cc

#include <iosfwd>
#include <utility>	// std::forward

template<typename T, class TAG>
class StrongTypedef{
private:
	using ST = StrongTypedef;

	T	v;

public:
	StrongTypedef() = default;

	template<typename UT>
	explicit StrongTypedef(UT &&v) : v(std::forward<UT>(v)){}

public:
	// we want this to be ugly

	const T &getValue() const{
		return v;
	}

	T &getValue(){
		return v;
	}

public:
	bool operator  == (const ST& other) const { return v == other.v; }
	bool operator  != (const ST& other) const { return v != other.v; }

	bool operator  <= (const ST& other) const { return v <= other.v; }
	bool operator  >= (const ST& other) const { return v >= other.v; }
	bool operator  >  (const ST& other) const { return v >  other.v; }
	bool operator  <  (const ST& other) const { return v <  other.v; }

public:
	ST operator     + (const ST& other) const { return ST{ v +  other.v }; }
	ST operator     - (const ST& other) const { return ST{ v -  other.v }; }
	ST operator     * (const ST& other) const { return ST{ v *  other.v }; }
	ST operator     / (const ST& other) const { return ST{ v /  other.v }; }

public:
	ST& operator   *= (const ST& other){ v *= other.v; return *this; }
	ST& operator   /= (const ST& other){ v /= other.v; return *this; }
	ST& operator   += (const ST& other){ v += other.v; return *this; }
	ST& operator   -= (const ST& other){ v -= other.v; return *this; }

public:
	ST  operator   ++ () const { ST other = &this; ++other; return other; }
	ST  operator   -- () const { ST other = &this; ++other; return other; }

	ST& operator   ++ (){ ++v; return *this; }
	ST& operator   -- (){ --v; return *this; }

public:
	ST operator     + () const { return +v; }
	ST operator     - () const { return -v; }

public:
	friend std::ostream& operator << (std::ostream& os, const ST &st){
		os << st.v;
		return os;
	}
};




#include <iostream>

int main(){
	struct LevelTag{};
	using  Level = StrongTypedef<int, LevelTag>;

	Level a{  4 };
	Level b{ 12 };


	// error
	// auto x = a + 5;

	++a;

	Level c = a * b;

	std::cout << a << '\n';

	return c.getValue();
}