Enables to have programs with modular configuration structs.

Different parts define modules that are then gathered and configured together in the main executable(s) of the project.

Example

Somewhere in the database module

struct database_settings : public conf::configuration {
  database_settings() : configuration("Database Options", "db") {
    param(url_, "url", "the Database URL");
    param(timeout_, "timeout", "connection timeout (in seconds)");
    param(retry_, "retry", "retry on connection loss");
    param(isolation_lvl_, "isolation_lvl",
          "default isolation level for transactions");
    param(flags_, "flags", "forwarded flags");
  }

  std::string url_{"localhost:5432"};
  int timeout_{30};
  bool retry_{false};
  isolation_level_t isolation_lvl_{isolation_level_t::SERIALIZABLE};
  std::vector<std::string> flags_;
};

Somewhere totally different

struct doomsday_settings : public conf::configuration {
  doomsday_settings() : configuration("Doomsday Options", "doom") {
    param(apocalypse_, "apocalypse", "THE END IS NEAR!");
  }

  conf::holder<std::time_t> apocalypse_{conf::parse_date_time("2012-12-21")};
};

Main

int main(int argc, char const** argv) {
  database_settings database_opt;
  doomsday_settings doomsday_opt;
  conf::options_parser parser({&listener_opt, &database_opt, &doomsday_opt});
  parser.read_command_line_args(argc, argv);

  if (parser.help()) {
    parser.print_help(std::cout);
    return 0;
  } else if (parser.version()) {
    return 0;
  }

  parser.read_configuration_file();

  parser.print_unrecognized(std::cout);
  parser.print_used(std::cout);

  // Initialize application and so on
}