alt Hacker NewsMy preferred solution would be:
You have 2 types
UnvalidatedEmail
ValidatedEmail
Then ValidatedEmail is only created in the function that does the validation: a function that takes an UnvalidatedEmail and returns a ValidatedEmail or an error object.
My preferred solution would be:
You have 2 types
UnvalidatedEmail
ValidatedEmail
Then ValidatedEmail is only created in the function that does the validation: a function that takes an UnvalidatedEmail and returns a ValidatedEmail or an error object.
That can work in some situations. One thing I won't like about it in some other situations is that you now have 2 nullable fields associated with your user, or whatever that email is associated with. It's annoying or even impossible in a lot of systems to have a guaranteed validation that user.UnvalidatedEmail or user.ValidatedEmail must exist but not both.