sub column {
    my $self = shift;
    my $c = shift;
    my @column;
-   foreach my $row ($self->rows) {
+   foreach my $row (0..$#{$self->rows}) {
      push(@column, $self->cell($row, $c));
    }
    wantarray ? @column : \@column;
  }
[download]

Method rows() returns an anonymous array or list of rows (arrayrefs), but the cell method works with indices.

update: added link

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}