如何正确使用boost::program_options::implicit_value作为字符串的矢量
How to properly use boost::program_options::implicit_value for vector of string?
代码证明:
boost::program_options::options_description options;
Parser::Parser(): options("Allowed options")
{
options.add_options()
("help,h", "produce help message")
("type,t", po::value<std::string>()->required()->implicit_value(""), "Type")
}
这条线路可以:
("type,t", po::value<std::string>()->required()->implicit_value(""), "Type")
如何添加此行才能正常工作?:
("file,f", po::value< std::vector<std::string> >()->required()->multitoken()->implicit_value(std::vector<std::string>(0,"")), "File(s)")
这是字符串的向量。
您只需要帮助选项描述就可以知道如何向最终用户显示默认值。
也就是说,通常implicit_value
会使用lexical_cast<>
来获得文本表示,但这(显然)对vector<string>
不起作用。因此,提供您自己的文本表示:
("file,f", po::value<strings>()->required()
->implicit_value(strings { "santa", "claus" }, "santa,claus"), "File(s)");
完整演示
在Coliru上直播
#include <iostream>
#include <boost/program_options.hpp>
namespace po = boost::program_options;
int main(int argc, char** argv) {
po::options_description options/*("Allowed options")*/;
using strings = std::vector<std::string>;
options.add_options()
("help,h", "produce help message")
("file,f", po::value<strings>()->required()->implicit_value(strings { "santa", "claus" }, "santa,claus"), "File(s)");
std::cout << options << "n";
po::variables_map vm;
po::store(po::parse_command_line(argc, argv, options, po::command_line_style::default_style), vm);
po::notify(vm);
auto types = vm["file"].as<strings>();
for (auto t : types)
std::cout << "Got: " << t << "n";
}
打印:
-h [ --help ] produce help message
-f [ --file ] [=arg(=santa,claus)] File(s)
Got: santa
Got: claus