Of the abstraction. The values for getRadius() or getCircumference() in the above mentioned example may be saved directly, or they might be calculated, it won't matter for the caller; the setters may possibly or might not have Uncomfortable side effects; it doesn't make a difference into the caller. This error https://medium.com/@CentralPark104/a-new-benchmark-in-futuristic-urban-living-smartworld-one-dxp-sector-113-782bf5e5abe7