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Elm04_20 - Chapter 20 Concepts for Object Databases CHAPTER...

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Chapter 20: Concepts for Object Databases CHAPTER 20: CONCEPTS FOR OBJECT DATABASES Answers to Selected Exercises 20.13 Convert the example of GEOMETRY_OBJECTS given in section 20.4.1from the functional notation to the notation given in Figure 20.3 that distinguishes between attributes and operations. Use the keyword INHERIT to show that one class inherits from another class. Answer: (GEOMETRY_OBJECTS to attribute/operation) define class GEO_OBJECT: type tuple ( shape : enumerated(rectangle, triangle, circle); refpoint : tuple ( x: float, y: float) ); operations area : float; end GEO_OBJECT; define class RECTANGLE: INHERITS GEO_OBJECT; type tuple ( width : float, height: float); operations square? : boolean; end RECTANGLE; define class TRIANGLE: INHERITS GEO_OBJECT; type tuple ( side1 : float, side2 : float, angle : float ); end TRIANGLE; define class CIRCLE: INHERITS GEO_OBJECT; type tuple ( radius : float ); operations diameter : float; ci rcumference : float; end CIRCLE; 20.14 Compare inheritance in the EER model (see Chapter 4) to inheritance in the OO model described in Section 20.4
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