Of this abstraction. The values for getRadius() or getCircumference() in the above case in point could be saved straight, or they could be calculated, it isn't going to issue for the caller; the setters may or may not have Unintended effects; it doesn't make any difference into the caller. See https://propertyingurugram.in/property-rates-in-gurugram-may-increase-by-70-per-cent-here-is-why/