Refactoring Practice

Copy this template repository to your own Github account. Then clone it to your computer and do the refactorings. Push your work to Github.

Each subdirectory contains some code that needs refactoring.

1. In this README, write one line describing each refactoring you apply and why.
2. Perform the refactoring in the subdirectory code.

time/timestamp.py

Refactor timestamp.py. 2 or 3 refactorings are possible.

Refactored list

• renamed method createTimeFromTimestamp to create_time_from_timestamp to match with PEP8 styles.
• extract method to is_valid_time to check valid time.
• remove else condition.

game_framework/gamelib.py

Look for refactorings in the class GameApp.

• Avoid side-effects: replace side effect with return value (the caller must use the return value)

• Encapsulate a collection - provide behavior that subclasses of GameApp need instead of requiring them to manipulate a collection that belongs to the GameApp class.

  • Hint: elements

Refactored list

• Make self.photo_image to be inline.
• In GameApp.create_canvas - replace side effect with return value.
• In GameApp.create_canvas - add parameters instead of accessing attributes.
• Replace string literal "news" with named constants tk.NSEW.
• Define elf.canvas_object_id in __init__ to avoid side-effects.
• Define canvas_object_id in __init__ to avoid side-effects.
• Introduce global variable - CANVAS_WIDTH, CANVAS_HEIGHT, TIMER_DELAY.

recipe/recipe.py and recipe/main.py

This uses a dataclass, which requires Python 3.7.

The Recipe class defines a recipe for a hot beverage with attributes:

• name - name of the recipe
• coffee - units of coffee
• chocolate - units of chocolate
• milk - units of milk
• sugar - units of sugar
• price - (float) price in Baht

Refactor main.py. What can you do to eliminate the long, boring code?

• Replace redundant code with a creational method.

Resources

• https://refactoringguru.com/refactoring
• Refactoring - Improving the Design of Existing Code by Martin Fowler. The bible on refactoring. The first 4 chapters explain the fundamentals.
• https://refactoring.com Online version of Fowler's book, but lacks explanation of the refactorings.