One of the other advantages of the decorator pattern is that wrapped objects can retain the type of the original object. As a result, you can use original and wrapped objects interchangeably, which is a significant advantage when your goal is to write flexible code. In this manner, you can easily extend the behavior of a particular object without modifying the original code.
Painters apply paint, stain, varnish and other finishes to buildings and other structures. They select the right paint or finish for the surface to be covered, taking into account durability, ease of handling, method of application and customer's wishes. Painters first prepare the surfaces to be covered, so that the paint will adhere properly. This may require removing the old coat of paint by stripping, sanding, wire brushing, burning, scraping, or water and abrasive blasting. Painters also wash walls and trim to remove dirt and grease, fill nail holes and cracks, sandpaper rough spots and brush off dust. On new surfaces, they apply a primer or sealer to prepare the surface for the finish coat. Painters also mix paints and match colors, relying on knowledge of paint composition and color harmony. They also cover walls and ceilings with decorative wall coverings made of paper, vinyl or fabric.
Aesthetics is the study of art and beauty; it was an important issue for 18th- and 19th-century philosophers such as Kant and Hegel. Classical philosophers like Plato and Aristotle also theorized about art and painting in particular. Plato disregarded painters (as well as sculptors) in his philosophical system; he maintained that painting cannot depict the truth—it is a copy of reality (a shadow of the world of ideas) and is nothing but a craft, similar to shoemaking or iron casting. By the time of Leonardo, painting had become a closer representation of the truth than painting was in Ancient Greece. Leonardo da Vinci, on the contrary, said that "Italian: La Pittura è cosa mentale" ("English: painting is a thing of the mind"). Kant distinguished between Beauty and the Sublime, in terms that clearly gave priority to the former. Although he did not refer to painting in particular, this concept was taken up by painters such as J.M.W. Turner and Caspar David Friedrich.