separation.rb

class Person
  attr_reader :attributes, :original_attributes
  
  def initialize(original = {})
    @original_attributes = original
    @attributes = original.clone
  end

  def sandwich=(value)
    attributes[:sandwich] = value
  end
  
  def destroy
    PersonPersistence.destroy(person)
  end
  
  def save
    PersonPersistence.save(self)
  end
  
  def self.find(identifier)
    self.new(PersonPersistence.find_attributes(identifier))
  end
end

class PersonPersistence
  def initialize(person)
    @person = person
  end

  def find_attributes(identifier)
    attributes = {}
    attributes.merge! GigyaPersonPeristence.find_attributes(identifier)
    attributes.merge! DatabasePersonPeristence.find_attributes(identifier)
  end
  
  def save
    transaction do
      GigyaPersonPeristence.save(person)
      DatabasePersonPeristence.save(person)
    end
  end

  def changes
    person.original_attributes.diff(person.attributes)
  end

  def self.save(*args)
    self.new(*args).save
  end
end

class GigyaPersonPeristence < PersonPersistence
  def save
    # calls to gigya
  end

  def changes
    super.slice(:attrs, :i, :care, :about)
  end
end

class DatabasePersonPeristence < PersonPersistence
  def save
    record.update(changes)
  end

  def changes
    super.slice(:attrs, :i, :care, :about)
  end

  private

  def record
    PersonRecord.find(person.id)
  end
end