Attached please find an implementation of two functors for John Torjo's boost::log library which I have called "file_appender" and "rolling_file_appender". Documentation is scant, so I'll try to describe them here. The "file_appender" is meant as a more-or-less drop-in replacement for John's write_to_file functor, except that it keeps the output file open instead of re-opening it for each write. "rolling_file_appender" derives from file_appender and allows the user to specify a maximum file size and a number of files to keep. After each write, it checks if the file is >= <max_size> and, if so, calls the rollover method. This method renames existing logfiles using a numbered suffix, keeping at most <num_files> backups. If <max_size> is specified as 0, rolling_file_appender behaves the same way as file_appender. If <num_files> is 0, there will be only one logfile which will be truncated every time it reaches <max_size>. Both of these objects support a "filename_factory" function which the caller can use to generate unique or date-stamped (or ...) filenames from a user-supplied filename "prototype". I've included a factory function called "strftime_filename_factory" which will take the filename prototype and run it through std::strftime. The rolling_file_appender uses boost::filesystem to handle file remove/rename operations. Feedback is welcome. -- Caleb Epstein caleb dot epstein at gmail dot com