$param_ref = \@_;    $param_ref = [ @_ ];

Note that in your "5.6" version, you have a reference to an array of aliases, while in your "5.005_03" version, all elements are copied. This matters when you try to mutate $param_ref->[$n]. See the source of Attribute::Property for evil stuff involving referencing @_ :) (Don't worry, it's very well tested).

Juerd # { site => 'juerd.nl', plp_site => 'plp.juerd.nl', do_not_use => 'spamtrap' }