[Boost-users] boost::program options - why no allow_unregistered() for environmental variable parser?

The environment seems to be the one place that is guaranteed to have unregistered options, because it is full of things (like $LD_LIBRARY_PATH) of no interest to the program doing the parsing. A call on parse_environment always throws on these. As far as I can see in the code, the way to avoid the throw is to pass parse_enviroment a function that checks for each of the options that are actually wanted and returns the null string for the rest. Of course, this duplicates what the parser just did. Is there a better way? Ivan