Max,

was there a reason why you choosen CString over std::string? *curious*

Btw, maybe you want to add a "parachute" to your TString::format() code: if there is '%n' in the format string (fmt) better don't evaluate the expression. Since you can't verify the argument types feeded on runtime, this could be exploited (by accident). Nobody really needs unsafe %n. Hope it helps.