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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display()
fly()
quack()
RedheadDuck
display()
quack()
RubberDuck
swim()
display
()
//
カモに関する他のメソッド
Duck
display()
DecoyDuck
quack()
Quackable
インタフェースはどうか？
ジョーは、経営幹部がこの製品を
6
ヶ月ごとに更新し
たがっている（更新方法は未定）というメモを受け取っ
たので、継承は解決策ではないだろうと気付きました。
ジョーは、仕様が変化し続け、プログラムに新しい
Duck
サブクラスを追加するたびに
fly()
と
quack()
を調べ、おそ
らくはオーバーライドしなければいけなくなることを理
解しました。しかも、この作業は永久に続くのです。
そのため、ジョーにはカモの型の（すべてではなく）
一部だけが飛んだり鳴き声をあげたりするためのよりわ
かりやすい方法が必要です。
この設計をどう思いますか？
Duck
スー パークラスか
ら
fly()
を取り除き、
fly()
メソッドを
含むFlyable()インタフェースを作成でき
るぞ。そうすれば飛ぶべきカモだけがその
インタフェースを実装し、
fly()
メソッドを
持つことになるな。また、すべてのカモが
鳴くわけではないので、
Quackable
インタ
フェースも作成したほうがよさそうだ。
fly()
Flyable
display()
fly()
quack()
MallardDuck
6
1
章
継承は解決策ではない
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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.