In my application, I have to deal with objects (Tests) which can come in a few more-specific flavors (such as Essay and MultipleChoice).   Each of these are subclasses of Test.   When I load the descriptor record from the database and set about the process of populating the object, one of the things that I can determine from the database-row is exactly what kind (subtype...) of Test it is.

What I am considering doing, in response to this, is to do (say...) bless $self,"Test::MultipleChoice"; ... where $self is at that point always blessed as the parent-class, Test.

But my obvious concern is, “Moose Magic.”   Would it work?   The magickal things that happen in a Moose constructor would not happen when re-blessing, and so I suspect that the answer is “no.”

Another Way To Do It™ would probably be to use Moose traits.   (And, in retrospect, maybe that is the much-better way to do it?)   But once again, will it work?   And, does that preclude me from using make_immutable?

Yet Another Way To Do It™ is with a separate “factory” object (or simply, package, that knows how to read the record, figure out what kind of Test to instantiate, instantiates that object and then hands a copy of the database-row to it.

The downside, perhaps, is that I can no longer say, “object, go load() yourself...”   And what if the user is making a new Test and at some point along the way decides that it is to be a MultipleChoice test?   (That might be an argument for Traits, if the Traits list can be changed on-the-fly.)

I don’t have anyone to impress here, but I will be living with this design for a very long time.   And so, I’d gratefully receive the Wisdom of the Monks.   “Several paths diverge in the wood” here, “and this will make all the difference.”