use Getopt::Long qw( );

Getopt::Long::Configure(qw( posix_default bundling ));
Getopt::Long::GetOptions(
   'help|h|?' => \&help,
   foo        => \$opt_foo,
   bar        => \$opt_bar,
)
   or usage();

# -vs-

while (@ARGV && $ARGV[0] =~ /^-/) {
   for (shift(@ARGV)) {
      $_ eq '--' and last;
      /^(?:--help|-?h|-\?)\z/ and help();
      $_ eq '--foo' and $opt_foo = 1, next;
      $_ eq '--bar' and $opt_bar = 1, next;
      usage("Unrecognized option \"$_\"");
   }
}