Attribute flopping

attr_flop.rb

def attr_flop(obj, attribute)
  old_value = obj.send(attribute)
  yield obj, old_value
  new_value = obj.send(attribute)
  obj.send("#{attribute}=", old_value)
  new_value
end


class Camera
  attr_accessor :position
end

cam = Camera.new
new_position = attr_flop(cam, :position) { cam.position += [1, 2, 0] }
# camera retains its original position, and you are still able to retrieve its new position

attr_flop(cam, :position) { frame_update(delta) } # camera is modified heavily during the frame update