No. That wouldn't make any sense at all!

Perhaps I should have gone with my second instinct and written that line as:

for my $cell (@$row) {
    if (! defined $cell) {
        $cell = ' ';
    }
}
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I didn't because the fairly trivial task of setting undefined cells to a space becomes the dominant code in the sample. I'd hoped that the line would be pretty much ignored, but in retrospect that was pretty silly really.