Jeff Garland <jeff <at> crystalclearsoftware.com> writes:
I'm writing a program with program_options (very cool and useful library, BTW) and I found myself wanting to print out the variable_map values for debugging purposes. Is there an easy way to do this?
No, not at this moment. The first problem is that variables_map is a wrapper over std::map<string, boost::any>, and you can't print boost::any, unless you know for sure it's some specific type. So, we need some dynamic_any, and I'm not sure if that library is being pushed into Boost. Second problem is that not all option types are printable, for example std::vector<string> is not. So, some method of detecting printability is needed. A similiar problem has arisen some time ago. The variable_value::as method used to resort to lexical_cast, if the stored type was not equal to the requested one. This, however, required that all types you put in variables_map could be created from string -- which is a drastic requirement.
Also couple of documentation nits: 1) From the first example....
if (vm.count("help")) { std::cout << desc << "\n";
I had to read the code to figure out that variable_map inherits from std::map, and this is why you can call this. Documentation only says:
class variables_map : : public boost::program_options::abstract_variables_map
Noted.
2) In the 'Storage Component' section -- there's this:
Let's consider an example:
variables_map vm; store(parse_command_line(argc, argv, desc), vm); store(parse_config_file("example.cfg", desc), vm); finish(vm); .... Finally the call to notify function runs user-specified notify functions and stores values into regular variables, if needed.
I assume 'finish' is supposed to be notify? I don't see any docs for finish.
Yes, the 'notify' is the new spelling. Hmm.. I think I've fixed that doc typo before leaving on vacation. - Volodya