June 2022
Beginner to intermediate
672 pages
17h 23m
Japanese
Content preview from Head Firstデザインパターン 第2版 ―頭とからだで覚えるデザインパターンの基本
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最初は、この原則は「実装に対してではなくインタフェー
スに対してプログラミングする」という原則によく似ている
ように感じられますが、この依存関係反転の原則のほうが抽
象化についてさらに強く主張しています。この原則は、高水
準コンポーネントは低水準コンポーネントに依存すべきでは
なく、むしろどちらも抽象に依存すべきであるというもので
す。
しかし、いったいこれは何を意味するのでしょうか？
それではまず、前のページのピザ店の図を再度よく見てく
ださい。
PizzaStore
は「高水準コンポーネント」であり、ピザ
実装は「低水準コンポーネント」です。
PizzaStore
は明らかに
具象ピザクラスに依存しています。
この原則は、高水準モジュールであれ低水準モジュールで
あれ、具象クラスではなく抽象に依存するようにコードを書
くべきだというものです。
しかし、どのようにすればよいのでしょうか？
非常に依存
関係の多い
PizzaStore
実装にこの原則を適用する方法を考えて
みましょう。
コード内での具象クラスへの依存関係を減らすことは、明
らかに「よいこと」です。実際に、この概念を形式化する
OO
設計原則があります。この原則には依存関係反転の原則
（
Dependency Inversion Principle
）という偉そうな正式名称さえ
あります。
以下にこの汎用的な原則を示します。
依存関係反転の原則
これでまたひとつ、経営幹部
を感心させるフレーズが増え
ました！
この本の購入代金よ
りも多くの昇給を得ることが
でき、同僚の開発者からも賞 ...
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and much more.
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.