Of this abstraction. The values for getRadius() or getCircumference() in the above mentioned example could be saved specifically, or they could be calculated, it will not matter to the caller; the setters could possibly or may not have Unwanted effects; it will not matter to the caller. See @michael-puckett-ii 's https://propertyingurugram.in/real-estate-a-surge-in-demand-for-independent-floors/