[boost] boost::exception questions

1) Why cant I just throw an boost::exception object? throw boost::exception() << boost::error_info<tag_errno>(100) << boost::error_info<tag_file_name>("hello"); 2) It might be nice to support "std::cerr << e", instead of requiring the use of e.what(). std::cerr << e; 3) Support for linking multiple error tags in a single expression might be useful and help in standarizing errors throughout an application. throw boost:::exception() << boost::error_info<tag_errorno,tag_filename,tag_size,tag_width>( (1,"output.txt",100,200);