Markinator

Term 1's Software Engineering assignment.

View the full project at https://github.com/jridz/Markinator

Description

A simple command line application for recording, viewing, and managing results for assignments and tests.

Requirements

1. Data entry
   • Allow users to enter results into the application.
2. Viewing results
   • Results can be viewed in a readable way.
3. Managing results
   • Allow users to delete results which may be incorrect or no longer needed.
4. File saving
   • Allow marks to be saved in a file that can be backed up or sent by the user.
5. Readable notices
   • Make errors, warnings, notices, and other important messages obvious and readable to the user.

Inputs, Processes & Outputs

Inputs

• Selected action
• Confirmations
• Subject name
• Selected subject
• Result name
• Score achieved
• Maximum possible score

Processes

• Open/Close File
• Parse JSON from file
• Handle selected action
• Handle user confirmation
• Create warnings, errors, and notices
• Alter data to reflect changes (creations, additions, or deletions)
• Write changes
• Make lists of subjects and results
• Handle incorrect selections and data entries

Outputs

• Welcome message
• Warnings, errors, and notices
• Lists of subjects and results
• Thank You message

Data Types

Data types used

1. Integers (int)
   • action in get_action()
   • len(data) in new_mark()
   • subject_index in view_all_marks()
2. Floating point nubers (float)
   • score and max_score in new_mark()
3. Strings (str)
   • confirmation in marksfile_exists()
   • subject_name in new_subject()
   • mark_name in new_mark()
4. Boolean (bool)
   • True and False from return in marksfile_exists()
5. List/Array (list)
   • data in new_subject()
   • subject["marks"] in new_mark()
6. None (None)
   • not from if not marksfile_exists() in main()
7. JSON
   • From marks.json
   • file in delete_mark()

Debugging Tools

Breakpoints

I used breakpoints to investingate the values of the program mid-execution. I used breakpoints to do the following:

• Fix incorrect starting iteration values in for loops.
• Find where data was in lists and how to parse the data.
• Stop before errors so I could diagnose.

Single Line Stepping

I used single line stepping to figure out what order functions were running in. I used single line stepping to do the following:

• Find why loops were/weren't looping infinitely.
• Look at how data was changing after each step taken.
• Go line by line to check for incorrect iteration or variable types.

Error Messages

I used Python's error messages to find many things (mostly spelling mistakes). It was a useful tool as it showed me when I was:

• Inputting the incorrect data into function arguments.
• Referencing variables that didnt't exist within the current function.
• Using the incorrect data types.

Special Print Messages

I made my own function print_special() which I use to notify the user when certain things happen. I also used them a fair amount as a way to debug. The function is often triggered when I enter incorrect data into the program. I used them to check if incorrect data was being handled correctly.

An example of where I used them was when you are entering in a result's score. Since errors wouldn't be triggered if the data is correct, I checked for data the should be errored by using the fact that the errors wouldn't trigger.

Error

Function stopping unexpectedly

In the view_result() function there was the following code:

# For each subject
for subject_index, subject in enumerate(data, start=1):
    # Print subject name
    print_special("underline", f"\n{subject['name']}")
    # Check if subject marks are empty
    if len(subject['marks']) == 0:
        print("(N/A) No marks for this subject.")
        # Skip current and move to next subject
        break
    # If not empty
    for mark_index, mark in enumerate(subject['marks'], start=1):
        # Print each result in this format: (1) Math Test: 10/100 [10.00%]
        print(f"({mark_index}) {mark['result_name']}: {mark['score']}/{mark['max_score']} "
              f"[{calculate_percentage(mark['score'], mark['max_score'])}]")

I was confused because if it was an empty it showed an error which was correct, but it wouldn't display the other following subjects which were correct. I threw in a breakpoint on the for loop and went step-by-step to see exactly why the function would quit before finishing. I eventually got to the line that has break, then immediatley after the for loop stopped and function ended. After looking into what break does I realised that I shouldn't have been using break. Instead I should have been using continue so it stops the current iteration in the loop then continues onto the next instead of breaking the loop.

After fixing the mistake I ended up with the following fixed code:

# For each subject
    for subject_index, subject in enumerate(data, start=1):
        # Print subject name
        print_special("underline", f"\n{subject['name']}")
        # Check if subject marks are empty
        if len(subject['marks']) == 0:
            print("(N/A) No marks for this subject.")
            continue
        # If not empty
        for mark_index, mark in enumerate(subject['marks'], start=1):
            # Print each result in this format: (1) Math Test: 10/100 [10.00%]
            print(f"({mark_index}) {mark['result_name']}: {mark['score']}/{mark['max_score']} "
                  f"[{calculate_percentage(mark['score'], mark['max_score'])}]")