const std::string& name, double default_value = 1,
std::function<double(std::vector<double> const&, double)> const& lambda = [](std::vector<double> const& values,
double) { return values.front(); });
- void parse(const std::string& values);
+ void parse(const std::string& string_values);
bool is_initialized() const { return initialized_; }
// Get the default value
double operator()();