As an example, consider a window in a windowing system. To allow scrolling of the window's contents, one may wish to add horizontal or vertical scrollbars to it, as appropriate. Assume windows are represented by instances of the Window interface, and assume this class has no functionality for adding scrollbars. One could create a subclass ScrollingWindow that provides them, or create a ScrollingWindowDecorator that adds this functionality to existing Window objects. At this point, either solution would be fine.
Painters prepare surfaces of building and other structures and then apply paint by means of brushes, rollers or sprayers. They work with varnish, enamels, lacquer and other materials. They may also paint interior rooms or cover walls with paper, fabrics, vinyls or other materials (paperhanger). They must be able to mix paints as well as do sandblasting and waterblasting.
Where The Dog Stars established Heller as a writer with a consistent, wickedly humorous voice, a formidable scene setter, and writer with philosophical underpinnings, this second novel shows those strengths fraying a bit. He’s adopting a voice here that isn’t always his own; he toys with the sentence structures of Hemingway and Raymond Carver, and the effect is a bit clumsy. However in the book’s second half he returns to vestiges of his first novel’s voice, and this is where his story becomes compelling.
Fresco is any of several related mural painting types, done on plaster on walls or ceilings. The word fresco comes from the Italian word affresco [afˈfresːko], which derives from the Latin word for fresh. Frescoes were often made during the Renaissance and other early time periods. Buon fresco technique consists of painting in pigment mixed with water on a thin layer of wet, fresh lime mortar or plaster, for which the Italian word for plaster, intonaco, is used. A secco painting, in contrast, is done on dry plaster (secco is "dry" in Italian). The pigments require a binding medium, such as egg (tempera), glue or oil to attach the pigment to the wall.
This code works for our purposes but it’s not exactly dynamic. If we wanted our initial simpleMsg object to sometimes act excited and sometimes quizzical, we could only do so by instantiating entirely new objects from the relevant subclass. Moreover, the ExcitedAndQuizzicalMessage is really just a combination of ExcitedMessage and QuizzicalMessage and probably shouldn’t have its own class. To fix these problems, let’s now return to the decorator pattern and see how it might help us.
A painter & decorator is responsible for preparing a surface and applying a range of finishes to it in response to the particular specifications of a job, paying close attention to detail to create a quality end product. The specific role of the painter & decorator is to prepare and decorate a particular surface in accordance with the wishes of the client. This will involve working on a wide variety of surfaces, including metal, wood, plaster and stone, and incorporating numerous materials, such as paint, varnish and wallpaper. The jobs involved depend upon the area that the painter & decorator works in. This can range from the industrial, specially-trained worker supplying skills for a large company, to the part-time, self-employed worker complementing a pension. A lot of the roles of the painter & decorator will come somewhere in between. If working for a larger construction firm, work can include more industrial-scale jobs, such as working as part of a team to prepare and paint the interior of a building or office. This will often involve specialist industrial techniques and larger equipment. If self-employed, this will normally include working independently on smaller jobs such as decorating private houses, schools, shops and other local buildings.
There have been a number of objections raised to this location -- the primary one is that it's the first real Python case where a line of code has an effect on a following line. The syntax available in 2.4a3 requires one decorator per line (in a2, multiple decorators could be specified on the same line), and the final decision for 2.4 final stayed one decorator per line.
You saw that, to define a decorator, you typically define a function returning a wrapper function. The wrapper function uses *args and **kwargs to pass on arguments to the decorated function. If you want your decorator to also take arguments, you need to nest the wrapper function inside another function. In this case, you usually end up with three return statements.
Color, made up of hue, saturation, and value, dispersed over a surface is the essence of painting, just as pitch and rhythm are the essence of music. Color is highly subjective, but has observable psychological effects, although these can differ from one culture to the next. Black is associated with mourning in the West, but in the East, white is. Some painters, theoreticians, writers and scientists, including Goethe, Kandinsky, and Newton, have written their own color theory.