Of this abstraction. The values for getRadius() or getCircumference() in the above mentioned case in point could possibly be stored right, or they could be calculated, it will not subject to the caller; the setters could or may not have Unwanted side effects; it won't issue on the caller. it https://share.evernote.com/note/694b2694-4368-a88f-fecc-749b6adfe0ab