问题
I can not seem to be able to read from config file multitoken options like I can from command line. What is the syntax for the config file?
This is how the option description is added:
//parser.cpp
- - -
po::options_description* generic;
generic=new po::options_description("Generic options");
generic->add_options()
("coordinate",po::value<std::vector<double> >()->multitoken(),"Coordinates (x,y)");
After which I parse command and config-files.
On command line '--coordinate 1 2' works. However, when I try in config file:
coordinate = 1,2
or
coordinate= 1 2
It fails giving a invalid_option_value exception. So what exactly is the syntax for config files in case of multitoken options?
回答1:
You can achieve the behavior you seek by writing a custom validator. This custom validator accepts :
./progname --coordinate 1 2
./progname --coordinate "1 2"
#In config file:
coordinate= 1 2
Here is the code:
struct coordinate {
double x,y;
};
void validate(boost::any& v,
const vector<string>& values,
coordinate*, int) {
coordinate c;
vector<double> dvalues;
for(vector<string>::const_iterator it = values.begin();
it != values.end();
++it) {
stringstream ss(*it);
copy(istream_iterator<double>(ss), istream_iterator<double>(),
back_inserter(dvalues));
if(!ss.eof()) {
throw po::validation_error("Invalid coordinate specification");
}
}
if(dvalues.size() != 2) {
throw po::validation_error("Invalid coordinate specification");
}
c.x = dvalues[0];
c.y = dvalues[1];
v = c;
}
...
po::options_description config("Configuration");
config.add_options()
("coordinate",po::value<coordinate>()->multitoken(),"Coordinates (x,y)")
;
References:
- http://www.boost.org/doc/libs/1_46_1/doc/html/program_options/howto.html#id2219998
- https://stackoverflow.com/tags/boost-program-options/hot
- Handle complex options with Boost's program_options
回答2:
In your configuration file, put each element of your vector on a different line.
coordinate=1
coordinate=2
回答3:
During finding myself confronted with a similar problem, I took the code above from Rob's answer (from May 4th, 2011), but had to change a few things due to changes in the boost architecture and C++11. I only cite the parts that I changed (or would have changed). The rest that is not within the validate function stays the same. For conformity reasons, I added the necessary std:: prefixes.
namespace po = boost::program_options;
void validate(boost::any& v,
const std::vector<std::string>& values,
coordinate*, int) {
coordinate c;
std::vector<double> dvalues;
for(const auto& val : values) {
std::stringstream ss(val);
std::copy(std::istream_iterator<double>(ss), std::istream_iterator<double>(),
std::back_inserter(dvalues));
if(!ss.eof()) {
throw po::invalid_option_value("Invalid coordinate specification");
}
}
if(dvalues.size() != 2) {
throw po::invalid_option_value("Invalid coordinate specification");
}
c.x = dvalues[0];
c.y = dvalues[1];
v = c;
}
The shift from po::validation_error to po::invalid_option_value was hinted in https://stackoverflow.com/a/12186109/4579106
来源:https://stackoverflow.com/questions/5884465/boostprogram-options-config-file-option-with-multiple-tokens