No such pseudo-hash field ""%s""
(F) You tried to access an array as a hash, but the
field name used is not defined.  The hash at index 0
should map all valid field names to array indices for
that to work.

##</code><code>##

$a->{'blah'} cmp $b->{'blah'}

##</code><code>##

$$a->{'blah'} cmp $$b->{'blah'}