Hi Reece, This just popped into my head. A lot of confusion seems to come from how you pass decorators. What I'm trying to say is that it can be very difficult to get the decorator strings right (especially for more complex things like XML) from the first time. I would suggest every formatter takes only one string which parses and finds all decorators itself. Each formatter will have one or more escape sequences which it uses to find the decorators. Something like: // in this case, '%' is used for identifying an element // '*' is to mean "leave default" (don't change) std::vector<int> v; // equivalent to your "[ ", ", ", " ]" std::cout << formatob(v, "[ %, % ]"); // eq. to "<< ", " | ", " >>" std::cout << formatob(v, "<< % | % >>"); // set only open/close decorators std::cout << formatob(v, "<< %*% >>"); // sets only the separator std::cout << formatob(v, "*% | %*"); // for pair - you have "%1" and "%2" std::vector< std::pair<int,long> > vp; // write XML std::cout << formatob(vp, containerfmt("<elem> % </elem><elem> % </elem>", pairfrt("<int>%1</int><long>%2</long>"))); How's that? Best, John -- John Torjo -- john@torjo.com Contributing editor, C/C++ Users Journal -- "Win32 GUI Generics" -- generics & GUI do mix, after all -- http://www.torjo.com/win32gui/ -- v1.4 - save_dlg - true binding of your data to UI controls! + easily add validation rules (win32gui/examples/smart_dlg)