Christoph Borgolte wrote: [...]
typedef boost::function<bool(const double& ,const double& )> CMP_FNC_DBL_DBL; typedef boost::function<bool(const double& )> CMP_FNC_DBL; typedef std::map<std::string, CMP_FNC_DBL_DBL> FUNCTION_MAP;
int main() { FUNCTION_MAP fm; fm["=="] = (boost::lambda::_1 == boost::lambda::_2); fm["!="] = (boost::lambda::_1 != boost::lambda::_2); //...
CMP_FNC_DBL_DBL fdd = fm["=="]; std::cout << fdd(11., 10.) << std::endl; //works
//Getting a function object via bind CMP_FNC_DBL_DBL fdd2 = boost::bind(&FUNCTION_MAP::operator[] , fm, std::string("=="));
This gives you a fdd2 that returns fm["=="]. It works because fm["=="] is convertible to bool, but doesn't really make much sense.
//that is what I really need: a CMP_FNC_DBL_DBL bound to a constant value
CMP_FNC_DBL fdd3 = bind( fdd, _1, 4.0 ); // ?