Readability counts～読みやすいことは重要だ

Python におけるソフトウェアエンジニアリングの原則

Adam Spannbauer

Machine Learning Engineer

Pythonの禅

import this

The Zen of Python, by Tim Peters (abridged)

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
The complex is better than complicated.
Readability counts.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.

説明的な名前

良くない名前

def check(x, y=100):
    return x >= y

説明的な名前

def is_boiling(temp, boiling_point=100):
    return temp >= boiling_point

やりすぎな名前

def check_if_temperature_is_above_boiling_point(
        temperature_to_check, 
        celsius_water_boiling_point=100):
    return temperature_to_check >= celsius_water_boiling_point

シンプルに保つ

The Zen of Python, by Tim Peters (abridged)

Simple is better than complex.
Complex is better than complicated.

Pizza Slice

ピザ作り - 複雑

def make_pizza(ingredients):
    # Make dough
    dough = mix(ingredients['yeast'],
                ingredients['flour'],
                ingredients['water'],
                ingredients['salt'],
                ingredients['shortening'])

    kneaded_dough = knead(dough)
    risen_dough = prove(kneaded_dough)

    # Make sauce
    sauce_base = sautee(ingredients['onion'],
                                ingredients['garlic'],
                                ingredients['olive oil'])

    sauce_mixture = combine(sauce_base,
                            ingredients['tomato_paste'],
                            ingredients['water'],
                            ingredients['spices'])

    sauce = simmer(sauce_mixture)
    ...

ピザ作り - シンプル

def make_pizza(ingredients):
    dough = make_dough(ingredients)
    sauce = make_sauce(ingredients)
    assembled_pizza = assemble_pizza(dough, sauce, ingredients)

    return bake(assembled_pizza)

リファクタリングのタイミング

良くない名前

def check(x, y=100):
    return x >= y

説明的な名前

def is_boiling(temp, boiling_point=100):
    return temp >= boiling_point

やりすぎな名前

def check_if_temperature_is_above_boiling_point(
        temperature_to_check, 
        celsius_water_boiling_point=100):
    return temperature_to_check >= celsius_water_boiling_point

練習しましょう！

Python におけるソフトウェアエンジニアリングの原則