Decorator Abstractions: Our decorator abstraction takes the form of the abstract MessageDecorator class, which also implements IMessage. The MessageDecorator class has a constructor that accepts an IMessage object as a parameter and then assigns it to a private variable. For its part, MessageDecorator doesn’t have any special behaviors and simply delegates GetMessage and PrintMessage calls to whichever IMessage object was injected into it.
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.
Photorealism is the genre of painting based on using the camera and photographs to gather information and then from this information, creating a painting that appears to be very realistic like a photograph. The term is primarily applied to paintings from the United States art movement that began in the late 1960s and early 1970s. As a full-fledged art movement, Photorealism evolved from Pop Art and as a counter to Abstract Expressionism.