Template ROOT macro that can be executed directly with command-line arguments

ROOTmacro_cmdline_args.C

//usr/bin/env root -l ${0}\(\""${0}"\",\""${*}"\"\); exit $?
/* ROOTmacro_cmdline_args.C
 *
 * template ROOT macro that can be executed (do not forget to
 * `chmod +x`) with command-line arguments
 *
 * Author: Luigi Pertoldi - pertoldi@pd.infn.it
 * Created: Sun 24 Mar 2019
 */

#include <getopt.h>

void usage() {
    std::cerr << "\n"
              << "USAGE: <progname> [options] [ROOTfile:objname]\n"
              << "\n"
              << "options:\n"
              << "  --help|-h : print this help message and exit\n"
              << "  ..."
              << "\n";
    gSystem->Exit(1);
}

void ROOTmacro_cmdline_args(std::string prog = "ROOTmacro_cmdline_args", std::string args = "") {

    // this is for getopt to work
    args = prog + " " + args;

    int argc = 0;
    char** argv = new char*[200];

    // get all arguments
    std::istringstream iss(args);
    std::string word;
    while (iss >> word) {
        char* tmp = new char[200];
        strcpy(tmp, word.c_str());
        argv[argc] = tmp;
        argc++;
    }

    const char* const short_opts = ":h";
    const option long_opts[] = {
        { "help",   no_argument,       nullptr, 'h' },
        // add other options...
        { nullptr,  no_argument,       nullptr, 0   }
    };

    // read in with getopt
    int opt = 0;
    while ((opt = getopt_long(argc, argv, short_opts, long_opts, nullptr)) != -1) {
        switch (opt) {
            // ...
            case 'h': // -h or --help
            case '?': // Unrecognized option
            default:
                usage();
        }
    }

    // get extra arguments
    std::vector<std::string> extra_args;
    for(; optind < argc; optind++){
        extra_args.emplace_back(argv[optind]);
    }

    if (!extra_args.empty()) {
        // ...
    }

    // get script location
    auto script_dir = prog.substr(0, prog.find_last_of('/'));

    return;
}

// vim: filetype=cpp