The decorate() proposal was that no new syntax be implemented -- instead a magic function that used introspection to manipulate the following function. Both Jp Calderone and Philip Eby produced implementations of functions that did this. Guido was pretty firmly against this -- with no new syntax, the magicness of a function like this is extremely high:
Did you get it? We just applied the previously learned principles. This is exactly what the decorators do in Python! They wrap a function and modify its behaviour in one way or the another. Now you might be wondering that we did not use the @ anywhere in our code? That is just a short way of making up a decorated function. Here is how we could have run the previous code sample using @.
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.
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. 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. 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.
Painters and paperhangers stand for prolonged periods. Their jobs also require a considerable amount of climbing, bending, kneeling, crouching, crawling and reaching with arms raised overhead often on scaffolding, ladders, and working at heights. Painters often work outdoors but seldom in wet, cold or inclement weather. Painters wear masks to reduce exposure to hazardous materials or paint fumes when working in areas with poor ventilation. Much of the work is done alone requiring independent thinking, safety awareness and ability to communicate with the customer. Special equipment is often used; such as equipment for welding, for use while scaffolding, on booms and lifts.
Aerosol paint (also called spray paint) is a type of paint that comes in a sealed pressurized container and is released in a fine spray mist when depressing a valve button. A form of spray painting, aerosol paint leaves a smooth, evenly coated surface. Standard sized cans are portable, inexpensive and easy to store. Aerosol primer can be applied directly to bare metal and many plastics.
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.