[boost program options] missing value validation
If I have a parameter which needs a value, but the value is not specified in the command line, I get an unknown exception in VisualStudio 2005. Meaning, if I declare a --compression=something, but then call the program with just --compression, the exception is thrown at the po::store() method. How do I intercept this and validate? I am just using the code from the example program: po::options_description desc("Allowed options"); desc.add_options() ("help", "produce help message") ("compression", po::value<std::string>(), "set compression level") ; po::variables_map vm; po::store(po::parse_command_line(ac, av, desc), vm); po::notify(vm); if (vm.count("help")) { std::cout << desc << "\n"; return 1; } if (vm.count("compression")) { std::cout << "Compression level was set to " << vm["compression"].as<std::string>() << ".\n"; } else { std::cout << "Compression level was not set.\n"; }
Andy F wrote:
If I have a parameter which needs a value, but the value is not specified in the command line, I get an unknown exception in VisualStudio 2005. Meaning, if I declare a --compression=something, but then call the program with just --compression, the exception is thrown at the po::store() method. How do I intercept this and validate?
I am just using the code from the example program:
po::options_description desc("Allowed options"); desc.add_options() ("help", "produce help message") ("compression", po::value<std::string>(), "set compression level") ;
po::variables_map vm; po::store(po::parse_command_line(ac, av, desc), vm); po::notify(vm);
if (vm.count("help")) { std::cout << desc << "\n"; return 1; }
if (vm.count("compression")) { std::cout << "Compression level was set to " << vm["compression"].as<std::string>() << ".\n"; } else { std::cout << "Compression level was not set.\n"; }
What is 'unknown exception'? You should have a try/catch block around use of po::store, and the what() method of the caught exception should contain something useful. - Volodya
Vladimir Prus <vladimir <at> codesourcery.com> writes:
What is 'unknown exception'? You should have a try/catch block around use of po::store, and the what() method of the caught exception should contain something useful.
- Volodya
Volodya, I get boost::program_options::invalid_command_line_syntax. I guess my question is this: If I want to make it so that if the user does not provide a value for the option, do I need to basically handle that in the catch block of the exception handling, or is there some other way of doing it upfront? Thanks, -Andy
Andy F wrote:
Vladimir Prus <vladimir <at> codesourcery.com> writes:
What is 'unknown exception'? You should have a try/catch block around use of po::store, and the what() method of the caught exception should contain something useful.
- Volodya
Volodya,
I get boost::program_options::invalid_command_line_syntax. I guess my question is this:
If I want to make it so that if the user does not provide a value for the option,
Seems like some part is left out of our question "if the user does not provide a value", then what?
do I need to basically handle that in the catch block of the exception handling, or is there some other way of doing it upfront?
- Volodya
Vladimir Prus <vladimir <at> codesourcery.com> writes:
Seems like some part is left out of our question "if the user does not provide a value", then what?
do I need to basically handle that in the catch block of the exception handling, or is there some other way of doing it upfront?
- Volodya
Sorry, I seem to be asleep at the wheel today. What I am saying is if the user does not provide a value for the option, and the value is required, is my only option to handle this in the catch block or is there a way to do this some other way? E.g. I define an option --env which much have a value. If the user just runs a.out --env, and not a.out --env=PROD, then it seems that the exception is thrown. Is there some way of checking it without doing the exception handling? Thanks, -Andy
Andy F wrote:
Vladimir Prus <vladimir <at> codesourcery.com> writes:
Seems like some part is left out of our question "if the user does not provide a value", then what?
do I need to basically handle that in the catch block of the exception handling, or is there some other way of doing it upfront?
- Volodya
Sorry, I seem to be asleep at the wheel today. What I am saying is if the user does not provide a value for the option, and the value is required, is my only option to handle this in the catch block or is there a way to do this some other way?
E.g. I define an option --env which much have a value. If the user just runs a.out --env, and not a.out --env=PROD, then it seems that the exception is thrown. Is there some way of checking it without doing the exception handling?
No, I don't think it's possible. - Volodya
participants (2)
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Andy F -
Vladimir Prus