Of this abstraction. The values for getRadius() or getCircumference() in the above mentioned instance may very well be saved specifically, or they might be calculated, it doesn't make a difference for the caller; the setters may well or might not have side effects; it doesn't matter to the caller. See https://propertyingurugram.in/old-vs-new-gurugram-attracting-investments-an-insight-into-citys-exponential-rise-as-premier-retail-hub/