in reply to
Re^3: Autovivification with hash of hashes
in thread Autovivification with hash of hashes
Thank you, that is what I was trying to convey.
I think the most important thing to do when working with structures that may contain anonymous hash refereneces is to avoid using tests that access a possibly non existent hash reference key by name, which, as far as I know, is the only way to cause autovivification. I am not sure what, other then ref could even be used.
This link provides some extended examples on the subject.