Hello, with boost log I have: using namespace boost::log; add_file_log ( "sample.log", keywords::format = ( expressions::stream << expressions::format_date_timeboost::posix_time::ptime("TimeStamp", "%H:%M:%S") << " [Rank: "<< expressions::attr<int>("Rank") << "]" << ": " << expressions::message ) ); which works fine. Now that may be a maximum stupid questions. But when I want to reuse the format expressions for other uses, e.g. another sink, how can I do that? i.e. how to declare and use a variable that holds that expressions? :-/ Thanks, Florian