I forgot to mention - I'm using PostgreSQL for object persistance so it'd be nice to think of implementations that wouldn't be alien to it. But then this is a more general question so however it makes sense for you.

__SIG__
use B;
printf "You are here %08x\n", unpack "L!", unpack "P4", pack
  "L!", B::svref_2object(sub{})->OUTSIDE;
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