I'd suggest that you call it "register" instead, as you proposed later. And force the user to export only the functions they need, explicitly. That way, it's easier to maintain: if you export fifteen functions, I need to check the codebase to see if any of those fifteen functions are still in use before I can remove the module from the codebase. If you only export what you actually use, then maintaining the code and removing unused modules becomes much easier. I'm lazy; I'd rather write down what I know when I know it (such as what functions I'm using from a given module), rather than waste time trying to reconstruct what I've forgotten.

Is redefining bless a bad idea? Should I just import a separate function like register instead to register the object after it's blessed using the built-in bless? E.g. register( bless $self, $class )

I don't see the need to redefine "bless"; just tell people to use "register" instead of "bless". You call the core "bless" function, so you should be able to use register exactly as you do "bless". In general, I find redefining builtin functions is always more confusing than not doing so. If I read "register", I know immediately that I don't know what's going on, and that I need to learn more. If I read "bless", I might be fooled into the wrong assumptions.

Just my $0.02
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Ytrew