Robust Codeを書くためのプログラミング姿勢について

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A robust codebase is resilient and error-free in spite of constant change.

stateDiagram
    direction LR
    Clean --> Readable
    Readable --> Understanble
    maintainable --> Improvable
    Understanble --> Improvable
    Improvable   --> Robust

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# Take a meal recipe and change the number of servings
# by adjusting each ingredient
# A recipe's first element is the number of servings, and the remainder
# of elements is (name, amount, unit), such as ("flour", 1.5, "cup")
def adjust_recipe(recipe, servings):
    new_recipe = [servings]
    old_servings = recipe[0]
    factor = servings / old_servings
    recipe.pop(0)
    while recipe:
        ingredient, amount, unit = recipe.pop(0)
        # please only use numbers that will be easily measurable
        new_recipe.append((ingredient, amount * factor, unit))
    return new_recipe

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def adjust_recipe(recipe, servings):
    old_servings = recipe.pop(0)
    factor = servings / old_servings
    new_recipe = {ingredient: (amount*factor, unit)
                  for ingredient, amount, unit in recipe}
    new_recipe["servings"] = servings
    return new_recipe

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def adjust_recipe(recipe, servings):
    """
    Take a meal recipe and change the number of servings
    :param recipe: a `Recipe` indicating what needs to be adusted
    :param servings: the number of servings
    :return Recipe: a recipe with serving size and ingredients adjusted
                    for the new servings
    """
    # create a copy of the ingredients
    new_ingredients = list(recipe.get_ingredients())
    recipe.clear_ingredients()

    for ingredient in new_ingredients:
            ingredient.adjust_proportion(Fraction(servings, recipe.servings))
    return Recipe(servings, new_ingredients)

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def create_author_count_mapping(cookbooks: list[Cookbook]):
    counter = {}
    for cookbook in cookbooks:
        if cookbook.author not in counter:
            counter[cookbook.author] = 0
        counter[cookbook.author] += 1
    return counter

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## defaultdict
from collections import defaultdict
def create_author_count_mapping(cookbooks: list[Cookbook]):
    counter = defaultdict(lambda: 0)
    for cookbook in cookbooks:
        counter[cookbook.author] += 1
    return counter

## Counter
from collections import Counter
def create_author_count_mapping(cookbooks: list[Cookbook]):
    return Counter(book.author for book in cookbooks)

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# 過度な抽象化: a + bで十分
class MathOperations:
    def add(self, a, b):
        return a + b

result = MathOperations().add(3, 4)


# Excessive Configuration: 普通にpackageを使おう
class DatabaseConnector:
    def __init__(self, host, port, username, password):
        # ... complex configuration code ...

    def connect(self):
        # ... complex connection logic ...

# Using the complex database connector
db = DatabaseConnector(host='localhost', port=5432, username='user', password='pass')
db.connect()


# 不必要な前処理の実施: 統計処理に不必要な前処理を担当したクラスの実装
class AdvancedDataProcessor:
    def __init__(self, data):
        # ... complex initialization ...

    def process_data(self):
        # ... complex data processing ...

# Using an overly complex data processor
data_processor = AdvancedDataProcessor(data)
data_processor.process_data()

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