This chapter is our first case study. We bring together the ideas from the previous chapters and provide an extended example. Some new ideas are introduced, and they should make more sense in the context of a full example.
This chapter is roughly divided into four parts:
The Course class: This section gives you an overview of the
S4class that will contain a list of grades for a course. The grades are kept in a list with each graded task as a separate object.The assignment classes: This section gives you an overview of the
S4classes used to keep the grades for a specific graded task. This class has two derived classes. One derived class is to keep track of grades that have a numeric score, and the other is to keep track of grades that consist of letters.Extending existing functions: This section includes a brief discussion of how existing functions can be extended to react in an appropriate way to an object that is one of the assignment classes. We focus...