Earlier, Gennadiy Rozental wrote: AL>> No doubt there's lots of implementation details left, (like AL>> using input_iterator_adaptor), but I think that this AL>> using idea. GR> You may use iterator_facade also. I just found that GR> implementing Input iterators using input_iterator_adaptor GR> is easier. It's located in Boost.Test details derectory GR> along with some usage examples. AL>> Am I on the right track? GR> Definitely. Looking forward to see it implemented. Later, Rob Stewart wrote: AL>>>> It works, but is considerably slower than the function AL>>>> returning a list. No doubt profiling will help track AL>>>> down what I'm doing inefficiently. RS>>> No doubt. GR>> I do not see anything in iterator implementation that GR>> suggest inherent inefficiency. RS> What he described sounded like he populated a container with the RS> results and then iterated that. Using the resulting iterator to RS> populate another container would, thus, reduce efficiency. Ahhhh. Now I understand you. Actually, the glob_iterator I've implemented and have just posted here: http://www.devel.lyx.org/~leeming/glob.zip (Docs can be viewed on line at: http://www.devel.lyx.org/~leeming/libs/glob/doc/html/) doesn't store anything but remains two to three times slower than the glob function that stores its results in a std::list. $ cd libs/glob/example $ time ./glob_function '*/*/*.hpp' '/home/angus/boost/cvs/' > /dev/null count_operator 1997 count_regex_match 1997 real 0m0.095s user 0m0.080s sys 0m0.020s $ time ./glob_iterator '*/*/*.hpp' '/home/angus/boost/cvs/' > /dev/null count_operator 1997 count_regex_match 1997 real 0m0.241s user 0m0.220s sys 0m0.010s I'm pretty sure I'm not doing anything daft. The 'count' data shows how many times I call the glob_predicate::operator() that decides whether a given file matches the globbing pattern. As you can see, this function is called the same number of times in each case. The algorithm to iterate over the files '*/*/*.hpp' is basically the same in the two cases, but the iterator version obviously has more 'if' statements in the inner loop. I guess that this is the killer and I don't think that there's anything we can do about it. Soooooooooo... do we flag that one up as a valient effort and move on or can the iterator be as efficient as the function and I just haven't found the right algorithm? Angu