Careful with that ||=, Eugene!
Did you really want to prohibit a cereal number of zero?

That's why I generally avoid using ||= to specify defaults.
Unless I'm very sure my incoming data won't ever be 0, "0", or "".

Besides, there are ways to tell if she is a witch:

    $name  = '' unless defined $name;
    $rank  = '' unless defined $rank;
    $c_num = '' unless defined $c_num;
[download]

or:

    foreach ($name, $rank, $c_num) { defined or $_ = '' }
[download]

or the strange-but-lovely:

    $_ = '' for grep !defined => ($name, $rank, $c_num);
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or the tried and true:

    $name  = '' if weight($name)  == weight($duck);
    $rank  = '' if weight($rank)  == weight($duck);
    $c_num = '' if weight($c_num) == weight($duck);
[download]

Err...

Oh, yes, I should also mention that next week, when Apocalypse III and Exegesis III appear, you'll find that Perl 6 is going to have a much nicer way to solve this problem.

Damian