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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開放
/
閉鎖原則（
Open-Closed Principle
）
いらっしゃいませ、
開店しています。必要な新たな振る
舞いでクラスを自由に拡張してください。ニーズや要
件が変わったら（将来変わる可能性があることは明ら
かです）、独自の拡張を作成すればよいのです。
申し訳ありません、
閉店しています。こ
れでいいのです。このコードをバグのない適切な
コードにするのに多くの時間を費やしたため、既存
コードを変更することはできません。コードは変更
に対しては常に閉じている必要があります。不満で
あればマネージャと話をしてください。
最も重要な設計原則の
1
つにたどり着きました。
私たちの目的は、既存コードを変更せずに、クラスを簡単に拡張して新しい振る舞いを
組み込めるようにすることです。これが実現できると何が得られるでしょうか？
変更に
対する適応力があり、新しい機能を受け入れて変更要求を満たせるほど十分柔軟性のあ
る設計が得られます。
86
3
章
開放
/
閉鎖原則（
Open-Closed Principle
）
設計原則
クラスを拡張に対しては開かれ
た状態にするべきだが、変更に
対しては閉じた状態にする。
3
章
Decorator
パターン
you are here
87
Q
：拡張に対しては開いており、変
更 に 対 し て は 閉 じ て
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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.