void read_formula_line(esi::string_t const& line, table_fluid_data & data) { namespace sp = boost::spirit::classic; using namespace sp; unsigned int index = 0; parse_info<wchar_t const*> info = sp::parse(line.c_str(), // begin grammar ( L'P' >> uint_p[assign_a(index)] //>> uint_p[assign_a(data.formulas[index-1].formula_id)] >> uint_p[boost::bind(&assign_i, _1, boost::ref(data.formulas [index-1].formula_id))] >> real_p[boost::bind(&assign_dbl, _1, boost::ref(data.formulas [index-1].coefficients[0]))] //>> real_p[assign_a(data.formulas[index-1].coefficients[0])] >> real_p[assign_a(data.formulas[index-1].coefficients[1])] >> real_p[assign_a(data.formulas[index-1].coefficients[2])] >> real_p[assign_a(data.formulas[index-1].coefficients[3])] >> real_p[assign_a(data.formulas[index-1].coefficients[4])] >> lexeme_d[*space_p] // necessary to clip off the last bit. ) , space_p); if (!info.full) throw std::runtime_error("Parse fail in formula line."); } The line is being parsed by the above code but the values are not being assigned by the assign_a nor by the boost::bind call to my own val = x setters. The setters are being called correctly, but the data is not getting through for some reason. It's like the data structure is being copied instead of referenced but I'm explicitely using references. Any idea what gives?