We're going to add geozones as user segments, so it's handy to have the
method in the UserSegments class.
We're also changing the `user_segment_emails` parameter name for
consistency and simplicity.
We're going to make it dynamic using the geozones. Besides, class
methods can be overwritten using custom models, while constants can't be
overwritten without getting a warning [1].
Makes the definition of segments with geozones a little cleaner. I
think it’s worth it, compared to the slight memory gain of using a
constant [2].
[1] warning: already initialized constant UserSegments::SEGMENTS
[2] https://stackoverflow.com/questions/15903835/class-method-vs-constant-in-ruby-rails#answer-15903970
Why:
Newsletter attribute `segment_recipient` is an integer to be used as
enum. There's no advantage to store a number instead of an string if the
ammount of elements in the table is not going to be huge, or we can take
advantage of using an enum.
Also maintaining both Newsletters enum paired with UserSegments::SEGMENTS
would be a maintenance burden.
How:
* Migration to change segment_recipient column from integer to string
* Removing enumeration from Newsletter model class
* Using UserSegments::SEGMENTS instead of Newsletter.segment_recipients
or integer values
