Started hacking on
Class::Sealed on the tube into work.
Noticed via the CPAN upload bot (#london.pm hosts an instance of
Bot::CPAN) and the modules list that just two days ago, Ian
Brayshaw had released Class::Declare, and today
Class::Declare::Attributes, which at first look seemed very similar
He doesn't seem to have picked up on the same notion of seal/override though, so maybe I'll carry on, or send him patches.