$ mkdir ~/cs170/labs/lab6 $ cd ~/cs170/labs/lab6
You've now been required to write two classes. The key detail about writing classes is that practice is the best way to get better at them. The more experience you have, the better your intuition will be when writing classes. So instead of lecturing today, you're going to spend the day writing at least 2 classes.
As many of you have likely noticed, I'm not an incredibly big fan of Inquire. However, The one part I do like about Inquire is the gradebook. It is much nicer than having a spreadsheet storing grades. However, I'd like to break away from using Inquire at some point. I could easily write my own gradebook software, but I think it might be better practice for you to write one.
Read this entire section before you start coding. There is a paper portion for this first!
You are going to write a simple gradebook program for CPSC 170. Towards that end, you need to write two different classes: Students and Gradebook. Your Student class should store all of the things associated with a student, namely quiz and assignment grades.
Your Gradebook class is simply going to be a collection of students. I should be able to get a list of all the quiz grades of a particular student, as well as get a list of all of the assignment grades for a particular student. I also might want to be able to add new students, and add new grades to a particular student.
Start by designing your classes on paper! Have either myself or one of the lab assistants look at this before you start writing. You should try to do this step without looking at the examples or hints below. Think about how you might be able to simplify your code, by putting methods in their appropriate places. Just because I listed an action above (or below, in the example) with a particular class doesn't mean you can't simplify things by writing additional methods in other classes.
>>> my_gradebook = Gradebook()
>>> my_gradebook.add_student("Thomas")
>>> my_gradebook.add_student("Maya")
>>> my_gradebook.add_assignment_grade("Maya", 100)
>>> my_gradebook.add_assignment_grade("Thomas", 95)
>>> my_gradebook.add_assignment_grade("Thomas", 100)
>>> my_gradebook.get_assignment_grade("Thomas")
[95, 100]
>>> my_gradebook.add_quiz_grade("Thomas", 90)
>>> my_gradebook.get_average("Thomas")
95.0
>>>
So you have a class that can represent a gradebook, but currently the only way to use it is to either write your own program or start the python interactive interpreter. Write a (text-based) menu-driven system that allows a user to add students, add grades, view grades, etc.
Another drawback to the current system is that grades go away once
the program is quit. It would be nice to be able to store the
current state of the gradebook, but we seem to be hitting this
problem . Luckily, Python has a
wonderful module known as Pickle, which
helpfully solves this problem for us. Now that we have written our
own classes, we can take full advantage of it!
Take a look at the Pickle documentation. Your program should read the pickled file at the beginning of the program, and write back to the file whenever you quit.
When you have finished, create a tar file of your lab6
directory. To create a tar file, execute the following commands:
cd ~/cs170/labs tar czvf lab6.tgz lab6/
To submit your activity, go to cseval.roanoke.edu. You should
see an available assignment called Lab Assignment 6.
Make sure you include a header listing the authors of the file.