Hi Tony,
Can anyone tell me the precise definition or behaviour of the order of execution of the user supplied functions to handle command line options defined in boost program options library. ...
For example, my option menu was defined as follows
boost::program_options::options_description menu("Valid Options"); menu.add_options() ("help,h", "Display this menu.") ("time,t", boost::program_options::value<double>(&time_arg_value) -> notifier(&my_function1) "Description of option") ("memory,m", boost::program_options::value<double>(&memory_arg_value) -> notifier(&my_function2), "Description of option") ("file,f", boost::program_options::value<std::vector<std::string>
(&file_arg_value) -> composing() -> notifier(&file_arg_handler<std::vector<std::string> >), "Something");
boost::program_options::variables_map menu_map;
boost::program_options::store(boost::program_options:: parse_command_line(argc, argv, menu), menu_map); boost::program_options::notify(menu_map);
This example misses one important piece -- the call to "nofity" function. As mentioned in http://boost.org/doc/html/program_options/overview.html#id548990 the user-provided notifiers are called by the "program_options::notify" function. The order of invocation is independed of the order on the command line, it's just lexicographical order of the option names.
Question is: Will the following two calls to the program result in different behaviour?
./Test --time 76 --memory 97 --help ./Test --memory 97 --time 76 --help
No.
I want my two functions for time and memory be independent of each other but I would like the function be called in the same order as the options specified on the command line. Sure I can test but can someone guarantee that what I discovered will remain valid in the future release of the library.
Why do you need specific order?
Another question: What will happen if this program was called on the command line with the following options.
./Test --file myfile1 --time 87 --file myfile2
Will the file_arg_handler be called first with composed arguments and then time function (my_function1) or will the time function (my_function1) be called first and then the file_arg_handler function. Can I count on it that what happens will always happen in the future? Is there definitions for the order of execution guarantee by the library?
There's no guarantee at all. The idea is most of the time you don't need specific order. If you describe your problem, I might offer more specific help. - Volodya