{

// ensure the env_var is all caps

std::transform(env_var.begin(), env_var.end(), env_var.begin(), ::toupper);

if (env_var == "PATH") return "path";

if (env_var == "EXAMPLE_VERBOSE") return "verbosity";

return "";

{

po::options_description config("Configuration");

config.add_options()

("path", "the execution path")

("verbosity", po::value<std::string>()->default_value("INFO"), "set verbosity: DEBUG, INFO, WARN, ERROR, FATAL")

;

po::variables_map vm;

store(po::parse_environment(config, boost::function1<std::string, std::string>(mapper)), vm);

notify(vm);

if (vm.count("path"))

{

std::cout << "First 75 chars of the system path: \n";

std::cout << vm["path"].as<std::string>().substr(0, 75) << std::endl;

}

std::cout << "Verbosity: " << vm["verbosity"].as<std::string>() << std::endl;

{

get_env_options();

return 0;