I've read countless posts on differences between Entities and Value objects and while I do think that at least conceptually I understand how the two differ, it appears that in some of these posts authors consider a particular domain concept to be a VO simply because it is immutable ( thus its state will never change, at least within that particular domain model ).
Do you agree that if the state of an object will never change within particular domain model, then this object should never be an entity? Why?
thank you
Do you agree that if the state of an object will never change within particular domain model, then this object should never be an entity? Why?
I'd say 90+% of entities will change at some point in their lifetime. But some entities might be unchangeable because of their nature in the domain - a PrepaidPhoneCard, a TransferOrder in a banking system for instance.
Some also like to make their Entities immutable by default because it helps shaping a design that preserves invariants and makes domain operations explicit : http://www.jefclaes.be/2013/04/designing-entities-immutability-first.html