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.
Some commonly used decorators that are even built-ins in Python are @classmethod, @staticmethod, and @property. The @classmethod and @staticmethod decorators are used to define methods inside a class namespace that are not connected to a particular instance of that class. The @property decorator is used to customize getters and setters for class attributes. Expand the box below for an example using these decorators.
Painting is an important form in the visual arts, bringing in elements such as drawing, gesture (as in gestural painting), composition, narration (as in narrative art), or abstraction (as in abstract art). Paintings can be naturalistic and representational (as in a still life or landscape painting), photographic, abstract, narrative, symbolistic (as in Symbolist art), emotive (as in Expressionism), or political in nature (as in Artivism).