Of this abstraction. The values for getRadius() or getCircumference() in the above mentioned instance might be stored directly, or they might be calculated, it doesn't make any difference towards the caller; the setters may well or may not have Uncomfortable side effects; it doesn't subject into the caller. See @michael-puckett-ii https://propertyingurugram.in/how-to-turn-rs-60-lakh-into-rs-5-crore-gurgaon-real-estate-advisor-reveals-how-the-rich-are-minting-money-through-this-strategy/