The decorator pattern is a design pattern that allows you to wrap an object such that it will appear to execute a given behavior in many different ways at different points in program execution. This is especially useful when you want an object to have different behaviors at but are unable to mutate the object. The decorator pattern is a useful way to implement dynamic behavior without needing an extended inheritance-based class hierarchy. To use the decorator pattern you need four elements: a component interface; a concrete component; a decorator abstraction; and, a concrete decorator. The interface sets the contract for both component and decorator behavior, the decorator abstraction contains a pointer to some concrete component, and the concrete decorators wrap a concrete component and override behavior if desired.
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.
NOTE  A Property Descriptor is not provided as an argument to a property decorator due to how property decorators are initialized in TypeScript. This is because there is currently no mechanism to describe an instance property when defining members of a prototype, and no way to observe or modify the initializer for a property. The return value is ignored too. As such, a property decorator can only be used to observe that a property of a specific name has been declared for a class.
Heller’s protagonist, Jim Stegner, is an unschooled but talented painter who struggles with drink, with womanizing, and with his temper. These traits have led him to be a killer, although Heller goes to great pains to let us know these acts are not premeditated. They’ve also, in accordance with these United States’ innate streak of violence, allowed him to be a cult figure - a talent around whom one feels it necessary to walk on eggshells. (For what it’s worth, this trait is to this reader and social observer the cause of a hollowness within the national psyche.) Stegner wants atonement for his acts, but he doesn’t know how to go about that. So Heller must allow Stegner to be the subject of retributive violence, which allows the painter, as might happen to a pre-adolescent child, to have atonement forced on him. Stegner is as a person and as a literary creation, a mess. Perhaps Heller intends him to be a faux Hemingway: hard drinking, bullying and a crybaby when those tables are turned on him. Stegner doesn’t seem to have the backbone about which an anti-hero’s fatal flaws can be built, though; he’s too much at the whims of fate for that. Heller tries to create philosophical depth for Stegner, but these attempts ring hollow. What he has created in Stegner, however, is a depiction of an instinctive artist, something the American psyche always seeks: talent and success untrammeled by subjecting that psyche to training and the lessons of culture and history. That Stegner is, in the end, a talented but pitiful figure, should tell the reader something very important: instinct that refuses at least a small measure of acculturation eventually become debased.
Writing a class decorator is very similar to writing a function decorator. The only difference is that the decorator will receive a class and not a function as an argument. In fact, all the decorators you saw above will work as class decorators. When you are using them on a class instead of a function, their effect might not be what you want. In the following example, the @timer decorator is applied to a class:
The decorator pattern is a design pattern that allows you to wrap an object such that it will appear to execute a given behavior in many different ways at different points in program execution. This is especially useful when you want an object to have different behaviors at but are unable to mutate the object. The decorator pattern is a useful way to implement dynamic behavior without needing an extended inheritance-based class hierarchy. To use the decorator pattern you need four elements: a component interface; a concrete component; a decorator abstraction; and, a concrete decorator. The interface sets the contract for both component and decorator behavior, the decorator abstraction contains a pointer to some concrete component, and the concrete decorators wrap a concrete component and override behavior if desired.
Join digital painting pioneer John Derry as he teaches basic and advanced creative techniques in Corel Painter 2019 that can get beginners up and running. John helps to acquaint you with the brand-new Painter interface as he steps through the creation of five travel posters. Along the way, he shines a spotlight on some of the hidden gems in the 2019 version of the software. Discover how to use tools like custom palettes and layouts to curate your work environment, how to adjust brushes for maximum performance, and how to approach illustrating using the Scratchboard tool. In addition, John shows how to create depth in your work by painting on layers. To wrap up, he goes over safety nets that can help you minimize unwanted accidents and demonstrates how to troubleshoot when a brush won't paint.
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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