The design appears to be appears to be adequate at first, but the more time I spent with working through the examples, the less I liked it.
Please could you state specific things you didn't like.
I think the implementation is pretty good. Overall, the author(s) have utilized modern c++ and established boost's "best-practices", including using boost::spirit for the "xml" parser. I'm not sure why he didn't use boost::spirit or boost::xpressive for the other parsers though.
Here's the current implementation status of various parsers: XML - Spirit JSON - Spirit INI - not using Spirit INFO - not using Spirit Registry - irrelevant Cmdline - irrelevant The reason I didn't use Spirit to parse INI file is its simplicty. If you look in ini_parser.hpp, read function fits on one screen. This will not be considerably simpler with Spirit, it might even be longer if you consider that you'll need to define grammar, function objects for actions. I agree it would be more maintainable with Spirit. INFO file is another story, I implemented first parsers for it long time ago, even before I started using boost. I once rewrote in it Spirit, but that - for some reason (maybe my incompetence at that time) - made parser significantly slower. So I returned to original version. Because it works fine as it is now, I see little reason to rewrite it. For those who may be interested, in examples dir there is an example which implements INFO with Spirit. It is intended to be a grammar specification (a nice side effect of Spirit is that it is a compilable and runnable grammar specification :-)
* What is your evaluation of the documentation?
Inadequate, at least compared to the better documented boost libraries. More work is need here.
Please specify what would you like expanded/added. I'm already aware that there is precious little docs on customization/traits part of the library. Best regards, Marcin