Michael van der Westhuizen wrote:
Vladimir Prus wrote:
Jonathan Graehl wrote:
I grepped through the program_options source and couldn't find anything about declaratively specifying required options (or even more specifically, min/max # of occurrences), except for positional options.
Does "min/max" number of occurrences makes much sense? In variables_map, an option is either present, or not, it cannot be present twice.
Yes, it does make sense. Two examples I can think of offhand are tcpdump and nmap, both of which allow you to specify the -v flag multiple times to increase verbosity.
That's multiple occurences of a value on the command line. But in variables_map, the option will be present only once -- supposedly, the number of "-v" occurences will be the value of the option. This is just like -I (include path) option. It can be specified several times, but end up as a vector of paths. I think that Jonathan was more interested in "option is required to be present in variables_map" functionality. On a related note, I don't think adding min/max number of occurences for command line is a good idea. That would make interface harder, and is only reasonable for most contrived command lines, and it's possible to enforce this restriction by manipulating parsed_options instance directly. The idea to require some option to be present in variables_map seems reasonable -- it's more common case. - Volodya