Contents:

• Overview
  • Newly Introduced Techniques
• Collaboration Policy
• External Specifications
• Files You Will Need
• Software Engineering Practices
• Suggested Steps of Progress
  • Providing Documentation
  • Unit Testing
• Submitting Your Assignment
• Grading Standards
• Extra Credit

Overview

The goal of this assignment is to add extra functionality to our previously defined Television class. In particular, we wish to add support for maintaining and manipulating a list of favorite channels.

Newly Introduced Techniques

• Working with a list as an instance variable

• Using loops for processing a list

• Providing Documentation Strings in Python

• Unit Testing

Collaboration Policy

For this assignment you must work individually in regard to the design and implementation of your project.

Please make sure you adhere to the policies on academic integrity in this regard.

External Specifications

From the user's perspective, the state of the television should include a list of select channels which we refer to as favorites. Internally, the favorites list can easily be maintained as an instance variable of type list. Your redesigned television should support the following three additional behaviors:

• addFavorite()
  When called, the television's current channel should be added to the list of favorites, if it is not already present on that list.

• removeFavorite()
  When called, the television's current channel should be removed from the list of favorites, if it had been on that list.

• jumpFavorite()
  When called, this behavior should have the end result of changing the current channel to a particular channel from the favorite list. Specifically, that favorite which is the next higher in value when compared to the current channel should be chosen. If no favorites exists which are higher in value than the current channel, the lowest of the favorite channels should be used. To inform the user of the new setting, this function should provide the chosen channel number as a return value.

  In the case that the favorite list is empty, the channel should not be changed, and nothing need be returned.

  Take care to ensure that jumpFavorite() properly maintains the prevChannel attribute for use in conjunction with subsequent calls to jumpPrevChannel().

Files You Will Need

We will provide you with our previously developed Television.py code. You may make your own personal copy of it by typing the following command from a terminal on turing:

cp /home/home0/goldwasser/lib/Television.py .

Software Engineering Practices

With this assignment, we would like to start enforcing two good practices in software engineering, namely documenting your work and testing your work. Python offers a conventional form of support for each of these efforts.

• Providing Documentation
  Python supports a special form of documentation for each class and method you define, known as a docstring. Specifically, if the very first line of any class definition or within the body of any method is a string literal, python interprets that string as a form of documentation. It can be examined by a user of an object by typing help(obj) for a given obj, or help(obj.method) for a given method supported by that obj. (See Zelle pp. 315-317 for further discussion).

  You will find that our original Television.py code already contains docstrings describing the existing functionality. You are required to provide sufficient docstrings for the three new functions you are writing.

• Unit Testing
  Locating and correcting mistakes becomes quite challenging on large software projects. One approach to handling this complexity is to individually test smaller portions of code. Therefore, for any class we write, it makes sense to provide some sample sequence of instructions to test the various behaviors and ideally demonstrate the correctness for a variety of settings. It becomes most convenient to write such test code in the same file as the original class definition. Of course, when we later want to use the class in a larger context, we need to import the class definition but presumably do not want to execute any of the test code.

  The conventional way we will accomplish this in Python is by writing a separate testing block starting with a command:

  if __name__ == '__main__':
     # perform sequence of tests...
  

  Such a test block should be placed at the end of the source file, following the actual class defintiions.

  You will find that our original Television.py code already contains (brief) unit testing of the existing functionality. You should extend such tests to adequately demonstrate your new functionality. Make sure not just to test one specific case, but a broad variety of scenarios and special cases which may arise.

Submitting Your Assignment

In the end, you should submit two files: your modified version of Television.py and a readme text file briefly discussing your efforts.

Please see details regarding the submission process from the general programming web page, as well as a discussion of the late policy.

Grading Standards

You will be graded based upon the correctness of your added functionality regarding the favorites list, as well as on your documentation and testing of the new functionality.

Extra Credit

To be announced...