Re: [Boost-users] simple serialization of boost::variant

28 May 2010

      Archie14  writes:
...
I use std::istream and std::ostream for binary serialization ( can't use 
boost::serialization) and can't find a way to serialize boost::variant. I'll appreciate a code sample or link to the 
documentation. Thanks.
This is a hack I came up with:
for ostream - using visitor pattern:

class outptype : public boost::static_visitor<>
{
public:
	outptype(std::ostream& stream) : _stream(stream){}
	void operator()(const int & i)
	{
		_oftype = 1;
		writevalue<byte>(_stream, _oftype);
		writevalue<int32>(_stream, i);
	}
	void operator()(const std::string & str)
	{
		_oftype = 2;
		writevalue<byte>(_stream, _oftype);
		writevaluestd::string(_stream, str);
	}
	void operator()(const double & val)
	{
		_oftype = 3;
		writevalue<byte>(_stream, _oftype);
		writevalue<double>(_stream, val);
	}
private:
	std::ostream& _stream;
	byte _oftype;
};

and for istream:
	byte oftype = readvalue<byte>(stream);
	switch (oftype)
	{
	case 1: 
		{
			int temp = readvalue<int32>(stream); 
			break;
		}
	case 2: 
		{
			std::string temp = readvaluestd::string(stream); 
			break;
		}
	case 3: 
		{
			double temp = readvalue<double>(stream); 
			break;
		}
	default:
		break;
	}
	return stream;
}

Is that directionally correct?