Class5.md

Class 5: Application Architecture

Activities

• Review code with partners and use code review rubric to assess quality
• Compare code quality of functions based on length and responsibility
• Discuss issues with ripple effects caused by tight coupling and ways to avoid it
• Discuss advantages of classes and object-oriented programming (OOP)

Objectives

After completing this class session and the associated tutorial challenges, students will be able to ...

• Assess aspects of code quality including organization and modularity
• Refactor functions that use structures as class instance methods
• Plan application architecture to prepare for future expansion

Challenges

These challenges are the baseline required to complete the project and course. Be sure to complete these before next class session and before starting on the stretch challenges below.

• Page 6: Application Architecture
  • Improve code organization and quality based on peer feedback on code review rubric
  • Write down your answers to questions about application architecture to plan improvements
  • Implement Dictogram class (histogram as a subclass of dict type) using dictogram starter code:
    • Implement add_count(word, count) - increase the frequency count of word in the histogram by count
    • Implement frequency(word) - return the frequency count of word in the histogram, or 0 if not found
    • Add types and tokens properties that track the number of word types and tokens in the histogram
    • Run python dictogram.py to test Dictogram class instance methods on a few small examples
    • Run pytest dictogram_test.py to run the dictogram unit tests and fix any failures
  • Implement Listogram class (histogram as a subclass of list type) using listogram starter code:
    • Implement add_count(word, count) - increase the frequency count of word in the histogram by count
    • Implement frequency(word) - return the frequency count of word in the histogram, or 0 if not found
    • Implement __contains__(word) - return a boolean indicating whether word is in the histogram
    • Implement _index(word) - return the index of the entry containing word if found in the histogram, or None if not found
    • Add types and tokens properties that track the number of word types and tokens in the histogram
    • Run python listogram.py to test Listogram class instance methods on a few small examples
    • Run pytest listogram_test.py to run the listogram unit tests and fix any failures
  • Restructure code files and functions to be more modular and flexible

Stretch Challenges

These challenges are more difficult and help you push your skills and understanding to the next level.

• Page 6: Application Architecture
  • Organize other app functions and classes based on your answers to app architecture questions
• Bonus challenges
  • Improve the speed of accessing word frequencies in the Listogram class by storing entries in sorted order and searching for them in a clever way
    • An elegant way to do this is to make a SortedListogram class that inherits from the Listogram class and overrides some instance methods to specialize their behavior to handle entries in sorted order
  • Want to make the Listogram class more convenient to use? Add methods so that it can be used as an iterable container, such as in a for loop like this:

    fish_text = 'one fish two fish red fish blue fish'
    histogram = Listogram(fish_text.split())
    for word in histogram:
        freq = histogram.frequency(word)
        print('{} occurs {} times'.format(word, freq))