In a previous article, we discussed how to use the strategy pattern to dynamically change an object’s behavior at runtime. Classically, polymorphism in object-oriented design is static and achieved through inheritance; however, with the strategy pattern you can accomplish the same goal dynamically. Indeed, this is an excellent way to handle situations when you need an object to exhibit different behavior at different times. However, it’s worth noting that the strategy pattern requires mutation of the object you’re working with. By using the strategy pattern, you are necessarily changing the algorithm that an object uses for a given behavior. In some situations, it may be preferable not to mutate a given object. Or more likely, you won’t even have the option of mutating an object because it may come from a codebase over which you have no control (such as an external library). Such cases are relatively common; however, it’s still possible to enhance an immutable object’s behavior. One effective means to do so is with the decorator pattern.
The Thistle Trafalgar Square Hotel is located on a quiet side street right in the heart of London's West End. All 108 bedrooms at this four-star hotel have been recently refurbished and offer a great standard of comfort and style. In addition, the Royal Trafalgar has a ground floor restaurant which also benefits from a terrace so you can experience al fresco dining in the center of London. The Role: Our guests deserve the best and that means operating hotels with the highest standards of maintenance and upkeep. As Maintenance Operative you will have the opportunity to contribute towards a fabulous guest experience by working hard to maintain the fixtures and fittings of the building. • Ensuring all defective fittings, breakdowns and malfunctions of equipment are fixed without delay • Communicating effectively and working closely with other departments such as Housekeeping • Ensuring that any emergencies are dealt with immediately and effectively minimizing any serious occurrences, hazards or inconvenience to guests and colleagues alike What we look for: • Positive, friendly individuals to join a like-minded team • NVQ electrician's qualification, experience in basic plumbing, basic carpentry, tiling and grouting skills and general handyperson skills with painting and decorating experience • Excellent communication skills • Total commitment to customer ser
None of these alternatives gained much traction. The alternatives which involve square brackets only serve to make it obvious that the decorator construct is not a list. They do nothing to make parsing any easier. The '<...>' alternative presents parsing problems because '<' and '>' already parse as un-paired. They present a further parsing ambiguity because a right angle bracket might be a greater than symbol instead of a closer for the decorators.
To calculate the tenth Fibonacci number, you should really only need to calculate the preceding Fibonacci numbers, but this implementation somehow needs a whopping 177 calculations. It gets worse quickly: 21891 calculations are needed for fibonacci(20) and almost 2.7 million calculations for the 30th number. This is because the code keeps recalculating Fibonacci numbers that are already known.
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.
There is some history in Java using @ initially as a marker in Javadoc comments  and later in Java 1.5 for annotations , which are similar to Python decorators. The fact that @ was previously unused as a token in Python also means it's clear there is no possibility of such code being parsed by an earlier version of Python, leading to possibly subtle semantic bugs. It also means that ambiguity of what is a decorator and what isn't is removed. That said, @ is still a fairly arbitrary choice. Some have suggested using | instead.
Tempera, also known as egg tempera, is a permanent, fast-drying painting medium consisting of colored pigment mixed with a water-soluble binder medium (usually a glutinous material such as egg yolk or some other size). Tempera also refers to the paintings done in this medium. Tempera paintings are very long lasting, and examples from the first centuries CE still exist. Egg tempera was a primary method of painting until after 1500 when it was superseded by the invention of oil painting. A paint commonly called tempera (though it is not) consisting of pigment and glue size is commonly used and referred to by some manufacturers in America as poster paint.
Digital painting is a method of creating an art object (painting) digitally and/or a technique for making digital art in the computer. As a method of creating an art object, it adapts traditional painting medium such as acrylic paint, oils, ink, watercolor, etc. and applies the pigment to traditional carriers, such as woven canvas cloth, paper, polyester etc. by means of computer software driving industrial robotic or office machinery (printers). As a technique, it refers to a computer graphics software program that uses a virtual canvas and virtual painting box of brushes, colors and other supplies. The virtual box contains many instruments that do not exist outside the computer, and which give a digital artwork a different look and feel from an artwork that is made the traditional way. Furthermore, digital painting is not 'computer-generated' art as the computer does not automatically create images on the screen using some mathematical calculations. On the other hand, the artist uses his own painting technique to create the particular piece of work on the computer.
Syntactic constraints. Python is a syntactically simple language with fairly strong constraints on what can and can't be done without "messing things up" (both visually and with regards to the language parser). There's no obvious way to structure this information so that people new to the concept will think, "Oh yeah, I know what you're doing." The best that seems possible is to keep new users from creating a wildly incorrect mental model of what the syntax means.
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.