use strict;
use warnings;
use Getopt::Long;

my @current_params;
my $counter;

while ( @current_params = get_next_set() ) {
  $counter++;
  print "\nloop $counter:";

  local @ARGV = @current_params;
  my ($alpha,$beta,$gamma);

  GetOptions (
              'Alpha|a'         => \$alpha,
              'Beta|b'          => \$beta,
              'Gamma|g'         => \$gamma,
             );

  if ( $alpha ) { print "ALPHA FOUND." }
  if ( $beta )  { print "BETA FOUND."  }
  if ( $gamma ) { print "GAMMA FOUND." }

}

########################
sub get_next_set
########################
{
  my @temp_set;
  while ( @ARGV ) {
   push @temp_set,shift @ARGV;
   last if $temp_set[$#temp_set] !~ /^-/
       and defined $ARGV[0]
       and $ARGV[0] =~ /^-/;
  }
  return @temp_set;
}   ##get_next_set

##</code><code>##

E:\>232942.pl -a -b FOO BAR -a -b -g BAR FOO -a -g FOO

loop 1:ALPHA FOUND.BETA FOUND.
loop 2:ALPHA FOUND.BETA FOUND.GAMMA FOUND.
loop 3:ALPHA FOUND.GAMMA FOUND.
E:\>