Very close. Parameters are passed as a list. When you assign something to a list, there's no way for Perl to know how long the list is supposed to be, so it slurps up everything available. It's kinda like the greedy * operator that's come under fire recently (Death to Dot Star).

If you need to get more than one list (whether list, array, or hash) to or from a subroutine, you need to use a reference, otherwise they'll blend together like a creamy fruit smoothie.

Codewise, sometimes I explicitly dereference-and-copy my arguments like you do, and sometimes I just act on them directly:

my $arr_ref = shift;
foreach my $item (@$arr_ref) {
    $item .= "foo";
}
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