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.
Using functions with "action-at-a-distance" through sys.settraceback may be okay for an obscure feature that can't be had any other way yet doesn't merit changes to the language, but that's not the situation for decorators. The widely held view here is that decorators need to be added as a syntactic feature to avoid the problems with the postfix notation used in 2.2 and 2.3. Decorators are slated to be an important new language feature and their design needs to be forward-looking, not constrained by what can be implemented in 2.3.
When we instantiate a SimpleMessage and then pass it to the various decorators, we now get new behavior. Moreover, since both the concrete component and the concrete decorators all implement / descend from IMessage, they are interchangeable as far as the program is concerned, meaning that we can loop over them together. Further, rather than having to create a new ExcitedAndQuizzicalMessageDecorator class, we were able to achieve the same effect by double wrapping a SimpleMessage object (first in an ExcitedMessageDecorator and then in a QuizzicalMessageDecorator). Finally, note that despite having been passed into various decorators, our simpleMsg object remains unchanged at the end of the program.
The term outsider art was coined by art critic Roger Cardinal in 1972 as an English synonym for art brut (French: [aʁ bʁyt], "raw art" or "rough art"), a label created by French artist Jean Dubuffet to describe art created outside the boundaries of official culture; Dubuffet focused particularly on art by insane-asylum inmates.[33] Outsider art has emerged as a successful art marketing category (an annual Outsider Art Fair has taken place in New York since 1992). The term is sometimes misapplied as a catch-all marketing label for art created by people outside the mainstream "art world," regardless of their circumstances or the content of their work.
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.

Landscape painting is a term that covers the depiction of natural scenery such as mountains, valleys, trees, rivers, and forests, and especially art where the main subject is a wide view, with its elements arranged into a coherent composition. In other works landscape backgrounds for figures can still form an important part of the work. Sky is almost always included in the view, and weather is often an element of the composition. Detailed landscapes as a distinct subject are not found in all artistic traditions, and develop when there is already a sophisticated tradition of representing other subjects. The two main traditions spring from Western painting and Chinese art, going back well over a thousand years in both cases.
Modern and Contemporary Art has moved away from the historic value of craft and documentation in favour of concept, leading some to say, in the 1960s, that painting as a serious art form is dead.[clarification needed] This has not deterred the majority of living painters from continuing to practice painting either as whole or part of their work. The vitality and versatility of painting in the 21st century defies the previous "declarations" of its demise. In an epoch characterized by the idea of pluralism, there is no consensus as to a representative style of the age. Artists continue to make important works of art in a wide variety of styles and aesthetic temperaments—their merits are left to the public and the marketplace to judge.
As Painter & Decorator you will ensure our 5* hotel is looking as pristine as possible through ensuring respective tasks are completed to the highest of quality with attention to detail as well as being confident to be guest facing throughout the hotel. Working within the Engineering Department you will be carrying out daily ad-hoc painting and decorating projects adhering to all health and safety precautions. Other duties will including sanding, wallpapering and other preventative maintenance tasks as required. At Sofitel London St James, we offer an array of great benefits including the following: Up to 4 free nights per year in AccorHotels in the UK and Ireland plus fixed-rate/discounted hotel stays and dining worldwide. 28 days holiday per year rising to 33 days linked to service (inclusive of Bank Holidays) plus a day off for moving house. Career development and progression including the AccorHotels mobility programme. Recognition initiatives and rewards for our Ambassadors who strive every day to offer our guests the best possible experience. Loyalty bonus, in-house guest experience, season ticket loan, up to 50% discount off Eurostar, childcare vouchers, meditation classes, monthly social events and much more…
Now, assume one also desires the ability to add borders to windows. Again, the original Window class has no support. The ScrollingWindow subclass now poses a problem, because it has effectively created a new kind of window. If one wishes to add border support to many but not all windows, one must create subclasses WindowWithBorder and ScrollingWindowWithBorder etc. This problem gets worse with every new feature or window subtype to be added. For the decorator solution, we simply create a new BorderedWindowDecorator—at runtime, we can decorate existing windows with the ScrollingWindowDecorator or the BorderedWindowDecorator or both, as we see fit. Notice that if the functionality needs to be added to all Windows, you could modify the base class and that will do. On the other hand, sometimes (e.g., using external frameworks) it is not possible, legal, or convenient to modify the base class.
Note that greet_bob(say_hello) refers to two functions, but in different ways: greet_bob() and say_hello. The say_hello function is named without parentheses. This means that only a reference to the function is passed. The function is not executed. The greet_bob() function, on the other hand, is written with parentheses, so it will be called as usual.

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In object-oriented programming, the decorator pattern is a design pattern that allows behavior to be added to an individual object, dynamically, without affecting the behavior of other objects from the same class.[1] The decorator pattern is often useful for adhering to the Single Responsibility Principle, as it allows functionality to be divided between classes with unique areas of concern.[2] The decorator pattern is structurally nearly identical to the chain of responsibility pattern, the difference being that in a chain of responsibility, exactly one of the classes handles the request, while for the decorator, all classes handle the request.
Modifying classes in this fashion is also possible, though the benefits are not as immediately apparent. Almost certainly, anything which could be done with class decorators could be done using metaclasses, but using metaclasses is sufficiently obscure that there is some attraction to having an easier way to make simple modifications to classes. For Python 2.4, only function/method decorators are being added.
As Painter & Decorator you will ensure our 5* hotel is looking as pristine as possible through ensuring respective tasks are completed to the highest of quality with attention to detail as well as being confident to be guest facing throughout the hotel. Working within the Engineering Department you will be carrying out daily ad-hoc painting and decorating projects adhering to all health and safety precautions. Other duties will including sanding, wallpapering and other preventative maintenance tasks as required. At Sofitel London St James, we offer an array of great benefits including the following: Up to 4 free nights per year in AccorHotels in the UK and Ireland plus fixed-rate/discounted hotel stays and dining worldwide. 28 days holiday per year rising to 33 days linked to service (inclusive of Bank Holidays) plus a day off for moving house. Career development and progression including the AccorHotels mobility programme. Recognition initiatives and rewards for our Ambassadors who strive every day to offer our guests the best possible experience. Loyalty bonus, in-house guest experience, season ticket loan, up to 50% discount off Eurostar, childcare vouchers, meditation classes, monthly social events and much more…
Concrete Decorator: Here we have two concrete decorators, ExcitedMessageDecorator and QuizzicalMessageDecorator, each of which descends from the abstract MessageDecorator class. However, these decorators do have special behavior in that they override the GetMessage and PrintMessage behaviors and enhance them by calling the base version from MessageDecorator (which in turn delegates to the relevant IMessage object) and then appending exclamations.
Thanks to enhanced support for multi-core processors and CPUs that use AVX2 extensions and extensive code optimizations, this is the fastest version of Painter yet. A huge selection of brushes are noticeably faster — some as much as twice as fast. You can also take advantage of faster document rendering when zooming, panning and rotating — up to 50% faster.
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