How to overload the stringstream insertion operator?

Question

I would like to parse a comma-separated-value string with a stringstream without having to call stringstream::ignore() for each value.

std::string csvString = "1,2,3,4";
int i1, i2;
std::stringstream ss(csvString);
ss >> i1;
ss >> i2;
if (ss.fail())
   throw "failed!"

Most tutorials about overloading the insertion operator use a user defined type as the the right hand operand. I have seen a few other examples. I suppose the solution would look something like this:

class ParserStream
{
private:
    std::stringstream & m_ss;
public:
    ParserStream(std::stringstream & ss): m_ss(ss){} 

    template<typename T>
    ParserStream & operator>>(T val)
    {
        m_ss >> val;
        m_ss.ignore();
        return *this;
    }    
};

It doesn't work. How could it work?

Answer 1

As cigien said in the comments, the problem was that the right hand side parameter is not passed by reference. The following code works correctly:

template<typename T>
ParserStream & operator>>(T & val)
{
    m_ss >> val;
    m_ss.ignore();
    return *this;
}