Create interpret_date_assignment_for class method

[geshafer]

Our usage of the interpret_date gem has created a pattern of defining
several assignment methods with the same logic inside of them which is
not helpful in the model and can clutter them with enough dates defined.
This commit introduces a class method that is included with
InterpretDate that allows you to define the attributes which need
their assignment interpreted by interpret date so we can clean up the
models.

Old example:

class Payment < ApplicationRecord
  include InterpretDate

  def issued_date=(value)
    super(interpret_date(value) || value)
  end

  def paid_date=(value)
    super(interpret_date(value) || value)
  end

  def sent_date=(value)
    super(interpret_date(value) || value)
  end

  def voided_date=(value)
    super(interpret_date(value) || value)
  end
end

New example:

class Payment < ApplicationRecord
  include InterpretDate

  interpret_date_assignment_for :issued_date,
    :paid_date,
    :sent_date,
    :voided_date,
end

[nspielman]

What do you think about shortening this method name? Some possible alternatives:

interpret_date_for
attr_interpret_date
interpret_date_attr
attr_writer_interpret_date
attr_interpret_date_writer

I like the first one in the list, the others are just thoughts.

[keiththomps]

Did you consider defining an ActiveRecord::Type for Dates? Moving forward that will be the more "rails-y" way to achieve this.

[keiththomps]

Class methods are annotated with a . instead of the # used for instance methods.