static function<bool(string&)> cfg_path(string &ref) { return [&ref](string &line) -> bool { clearpath(line); ref = move(line); return true; }; }
string makepath(string const & path1, string const & path2) { return clearpath(path1 + PATH_DIR_SEP + path2); }
static bool cfg_database(std::string &line) { clearpath(line); opt_default_db = line; return true; }