使用 Boost 库程序选项的必需参数和可选参数
我正在使用 Boost 程序选项库来解析命令行参数.
I'm using Boost Program Options Library to parse the command line arguments.
我有以下要求:
- 一旦提供了帮助",所有其他选项都是可选的;
- 如果未提供帮助",则需要所有其他选项.
我该如何处理?这是我处理这个的代码,我发现它很多余,我认为一定有一个容易做到的,对吧?
How I can deal with this? Here is the my code handling this, and I found it's very redundant, and I think there must be an easy to do, right?
#include <boost/program_options.hpp>
#include <iostream>
#include <sstream>
namespace po = boost::program_options;
bool process_command_line(int argc, char** argv,
std::string& host,
std::string& port,
std::string& configDir)
{
int iport;
try
{
po::options_description desc("Program Usage", 1024, 512);
desc.add_options()
("help", "produce help message")
("host,h", po::value<std::string>(&host), "set the host server")
("port,p", po::value<int>(&iport), "set the server port")
("config,c", po::value<std::string>(&configDir), "set the config path")
;
po::variables_map vm;
po::store(po::parse_command_line(argc, argv, desc), vm);
po::notify(vm);
if (vm.count("help"))
{
std::cout << desc << "
";
return false;
}
// There must be an easy way to handle the relationship between the
// option "help" and "host"-"port"-"config"
if (vm.count("host"))
{
std::cout << "host: " << vm["host"].as<std::string>() << "
";
}
else
{
std::cout << ""host" is required!" << "
";
return false;
}
if (vm.count("port"))
{
std::cout << "port: " << vm["port"].as<int>() << "
";
}
else
{
std::cout << ""port" is required!" << "
";
return false;
}
if (vm.count("config"))
{
std::cout << "config: " << vm["config"].as<std::string>() << "
";
}
else
{
std::cout << ""config" is required!" << "
";
return false;
}
}
catch(std::exception& e)
{
std::cerr << "Error: " << e.what() << "
";
return false;
}
catch(...)
{
std::cerr << "Unknown error!" << "
";
return false;
}
std::stringstream ss;
ss << iport;
port = ss.str();
return true;
}
int main(int argc, char** argv)
{
std::string host;
std::string port;
std::string configDir;
bool result = process_command_line(argc, argv, host, port, configDir);
if (!result)
return 1;
// Do the main routine here
}
推荐答案
我自己也遇到过这个问题.解决方案的关键是函数 po::store
填充 variables_map
而 po::notify
会引发遇到的任何错误,所以 vm
可以在发送任何通知之前使用.
I've run into this issue myself. The key to a solution is that the function po::store
populates the variables_map
while po::notify
raises any errors encountered, so vm
can be used prior to any notifications being sent.
因此,根据 蒂姆,根据需要将每个选项设置为必需,但在处理了帮助选项后运行 po::notify(vm)
.这样它就会退出而不会抛出任何异常.现在,将选项设置为必需,缺少选项将导致 required_option
异常被抛出并使用它的 get_option_name
方法你可以将你的错误代码减少到一个相对简单的 catch
堵塞.
So, as per Tim, set each option to required, as desired, but run po::notify(vm)
after you've dealt with the help option. This way it will exit without any exceptions thrown. Now, with the options set to required, a missing option will cause a required_option
exception to be thrown and using its get_option_name
method you can reduce your error code to a relatively simple catch
block.
作为附加说明,您的选项变量是直接通过 po::value< 设置的.-type- >( &var_name )
机制,因此您不必通过 vm["opt_name"].as< 访问它们.-type- >()
.
As an additional note, your option variables are set directly via the po::value< -type- >( &var_name )
mechanism, so you don't have to access them through vm["opt_name"].as< -type- >()
.
Peters 的回答
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