maybe I'm totally out of track (it's been a long and hard week :-), but I would go with something like:

$date = (ref $date =~ /ARRAY/) ? $date : [ split(/\D+/, $date) ];
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it is safe enough, I think, to treat the reference as an array if it "implements" an array (eg. if it's something like Foo::Bar=ARRAY(0xdeadbeef)) the same way it is safe enough to call $object->{property} when $object is something like Foo::Bar=HASH(0xdeadbeef).

don't know, however (I don't have time to check now), if this works for tied arrays.

someone correct me please if I'm wrong :-)