These are known issues. For persistance, Object::InsideOut and Class::Std::Storable both offer Storable hooks. (Also see my digression today: Hooks like Storable for Dumper?).

I plan on covering a lot of this at my Inside-Out Tutorial at the January Perl Seminar NY. Here's a snippet from my presentation -- you've really got four options for how to implement the storage/index of inside-out objects:

• Array-based storage, with sequential object ID's stored in blessed scalar

• Hash-based storage, with a generated unique object ID cached in a blessed scalar

• Hash-based storage, with memory address of a blessed scalar cached in the scalar

• Hash-based storage, with memory address of the blessed reference used directly

Each has pros and cons. There's some discussion on using memory addresses versus a UUID in Threads and fork and CLONE, oh my!. The latter is probably the way to go if you want to check if the object thawed is the same as an existing object.

For another good summary of inside-out issues, read Anti-inside-out-object-ism