This assignment is designed to give you experience in refactoring existing code. It will also be good preparation for the midterm since it will encourage you to look closely at some of the demo code from class.

1 Assignment Goals

Example 08-BarGraph has been extensively discussed in class. Several design issues, bugs, and places for improvement were mentiond. The process of taking an existing piece of code and modifying it to improve its design and style while preserving functionality is called refactoring. The purpose of this assignment is to give you a deeper understanding of the many design decisions that went into the relatively simple bar graph program, and to experience what is involved in refactoring.

In particular, any changes are likely to result in new compiler errors as variables are renamed, types are changed, and code is moved around. Since you are starting with code that compiles, a compiler error that results from a change you made shows you where to look for the problem. You should work a little bit at a time and recompile after each related group of changes to make sure you haven’t broken things.

2 Problem

You should make the following changes in 08-BarGraph:

1. (4 points) The code that opens the input file and reads it used to be split between run() and the Graph constructor. The body of run() should be moved to a class function in a new class Controller. The file reading code in the Graph constructor should also be moved to one or more class functions in Controller. The modified run() in main.cpp should instantiate Controller and pass control to a function in it. The function Graph::insert() will need to be made public.
2. (1 point) In row.hpp, class Cell should be eliminated. The row should be represented variable of type vector<Item> instead of my a linked list of Cell.
3. (3 points) In graph.hpp, the element type of array bar should be changed from Row⋆ to Row. This will have ramifications elsewhere in your program. In particular, Row::insert() should call vector<Item>::push_back(Item(name, score)) in order to create and insert a new Item into a row rather than using new to create an Item⋆.
4. (1 point) You should initialize the bar array by declaring it with the initializer list
        = {0,1,2,3,4,5,6,7,8,9,10}.
5. (2 points) The potential infinite loop in the Graph constructor should be fixed before it is moved to the Controller class.
6. (1 points) Every use of C-style strings (char⋆ or char[]) should be changed to use a C++ string instead. (The one exception is argv in main(), which should remain a char⋆ array.)
7. (2 points) In row.cpp, the cleverness in constructing the label string should be replaced by a straightforward use an ostringstream. First figure out what you would have to do to print the label for row rowNum if you were just printing to cout. Then “print” the same way to an ostringstream and use the ostringstream function str() to obtain the underlying string.
8. (1 point) You should eliminate rowNest.hpp and the conditional code that depends on the NEST preprocessor variable, and make corresponding changes to Makefile.
9. (1 point) With the above changes, there should be no further occurrences of new or delete in your program, so remove all destructors from your code as well as any constructors that don’t do anything useful.

Grading Rubric

Your assignment will be graded according to the scale given in Figure 1 (see below).