def setters
      mods = {}
      changes.each_pair do |name, changes|
        if changes
          old, new = changes
          field = fields[name]
          key = atomic_attribute_name(name)
          if field && field.resizable?
            field.add_atomic_changes(self, name, key, mods, new, old)
          else
            mods[key] = new unless atomic_unsets.include?(key)
          end
        end
      end
      mods
    end
def setters
      mods = {}
      changes.each_pair do |name, changes|
        if changes
          old, new = changes
          field = fields[name]
          key = atomic_attribute_name(name)
          if field && field.resizable?
            field.add_atomic_changes(self, name, key, mods, new, old)
          else
            mods[key] = new unless atomic_unsets.include?(key)
          end
        end
      end
      mods
    end
Gets all the new values for each of the changed fields, to be passed to
 a MongoDB $set modifier.

 @example Get the setters for the atomic updates.
   person = Person.new(:title => "Sir")
   person.title = "Madam"
   person.setters # returns { "title" => "Madam" }

 @return [ Hash ] A +Hash+ of atomic setters.

 @since 2.0.0