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Exercise 7.2
Point3D: A client or a subclass of Point2D?

The purpose of this exercise is to sharpen your understanding of the difference between "being a client of class C" and "being af subclass of class C".

The class Point3D extends Point2D by means of inheritance.

As an alternative, the class Point3D may be implemented as a client of Point2D. In more practical terms this means that the class Point3D has an instance variable of type Point2D. Now implement Point3D as a client of Point2D - such that a 3D point has a 2D point as a part.

Be sure that the class Point3D has the same interface as the version of class Point3D from the course material.

Evaluate the difference between "being a client of" an "extending" class Point2D. Which of the solutions do you prefer?