April 2022
Beginner to intermediate
344 pages
9h 32m
Japanese
Content preview from はじめての設計をやり抜くための本 第2版 概念モデリングからアプリケーション、データベース、アーキテクチャ設計、アジャイル開発まで
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導
入
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設
計
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キ
テ
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チ
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3
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処理の共通化（
DRY
）
DRY（Don’t Repeat Yourself）という言葉があります。「繰り返すな！」
という意味ですが、同じ処理を書かないこと以外にも、仕様書や設計書、プ
ロセス、プログラムのコメントなどを含めて安易な重複を戒める言葉です。
似た意味の言葉で、Once And Only Once（OAOO）というものもありま
す。直訳すれば「1度だけ、ただ1度だけ」という意味です。言葉だけを比
べればどちらも重複を戒めていることに変わりはありません。実際には意味
が違いますが、本書は些細な言葉の解釈をするものではありません。簡単に
言えば、Once And Only Onceはコードを重複しないことに言及している
コピペを繰り返しつつ、それぞれが変更されると似たようなものがいくつもできてしまう。
オリジナルにバグがあることがわかった場合にはコピペされたものすべてに修正が必要になる。
コピペをせずにDRYを維持するために共通化設計をすべきである。
Original
Copy Copy of Copy
Copy Copy of Copy
変更
変更
変更
変更
図
6
-
11
：コピペによる多重メンテナンス
283
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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.