A twist on particle's solution. Instead of saving to an array, you pass in a referance to that array:

sub separate_data {
    my $array = shift;
    $array = [ split / /, $data[$a] ];
}

my (@array1, @array2, @array3);
seperate_data(\@array1);
seperate_data(\@array2);
seperate_data(\@array3);
[download]

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I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
-- Schemer

Note: All code is untested, unless otherwise stated