`no underscore`

        package underscore;
        use Carp;

        sub TIESCALAR {        
            my $class = shift;
            my $dummy;
            return bless \$dummy => $class;
        }

        sub FETCH { croak "Read access to \$_ forbidden"  } 
        sub STORE { croak "Write access to \$_ forbidden" }

        sub unimport { tie $_ => __PACKAGE__ }
        sub import { untie $_ }

1;