gistfile1.cpp

template <typename T>
class print_binary_helper
{
public:
  static_assert(std::is_integral<T>::value,
		"Cannot print non-integer in binary.");

	//template <typename U>
	friend print_binary_helper<T> print_binary(T value);

	// <typename U>
	friend std::ostream& operator<<(std::ostream& sink,
		const print_binary_helper<T> source);

	//template <typename U>
	friend std::wostream& operator<<(std::wostream& sink,
		const print_binary_helper<T> source);

private:
	explicit print_binary_helper(T value) :
	mValue(value)
	{}

	template <typename Sink, typename Char>
	Sink& do_print(Sink& sink, Char on, Char off) const
	{
		for (auto mask = T(1) << (std::numeric_limits<T>::digits - 1);
			mask != 0; mask >>= 1)
		{
			const auto isOn = (mValue & mask) != 0;
			sink << (isOn ? on : off);
		}

		return sink;
	}

	T mValue;
};