Of the abstraction. The values for getRadius() or getCircumference() in the above mentioned illustration may very well be stored straight, or they could be calculated, it doesn't make a difference to your caller; the setters might or may not have Negative effects; it will not issue towards the caller. Present https://share.evernote.com/note/9f77c0f1-9e84-2ae0-ce6b-48761e7f252c