(The Watch as an Object) You are probably wearing on your wrist one of the world’s most common types of objects—a watch. Discuss how each of the following terms and concepts applies to the notion of a watch: object, attributes, behaviors, class, inheritance (consider, for example, an alarm clock), encapsulation, interface, information hiding, data members and member functions.

Question

What will be an ideal response?

Answer 1

The entire watch is an object that is composed of many other objects (such as the moving parts, the band, the face, etc.) Watch attributes are time, color, band, style (digital or analog), etc. The behaviors of the watch include setting the time and getting the time. A watch can be considered a specific type of clock (as can an alarm clock). With that in mind, it is possible that a class called Clock could exist from which other classes such as watch and alarm clock could inherit the basic features of the clock. The watch is an abstraction of the mechanics needed to keep track of the
time. The user of the watch does not need to know the mechanics of the watch in order to use it; the user only needs to know how to read the face of the watch and that the watch keeps the proper time. In this sense, the mechanics of the watch are encapsulated (hidden) inside the watch. The interface to the watch (its face and controls for setting the time) allows the user to set and get the time. The user is not allowed to directly touch the internal mechanics of the watch. All interaction with the internal mechanics is controlled by the interface to the watch. The data members stored in the watch are hidden inside the watch and the member functions (looking at the face to get the time and setting the time) provide the interface to the data.