sub first {
  print "This is first\n";
}
sub second {
  print "This is second\n";
}
sub dispatch {
  no strict 'refs';
  my $command = shift;
  print "In dispatch, command = $command\n";
  my %dispatch = ( 'a'=>'first', 'b'=>'second' );
  &{$dispatch{$command}}();
}

dispatch('a');
dispatch('b');