November 2025
Intermediate to advanced
984 pages
16h 17m
Japanese
Content preview from Fluent Python 第2版 ―Pythonicな思考とコーディング手法Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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12章シーケンスの特殊メソッド
対象がアヒル「である」かを調べるべきではありません。各自のプログラムの中でアヒルのどのようなふるまいが求められているかに応じて、アヒル「のように鳴く」か、アヒル「のように歩く」かなどといった観点から判断を下すべきです。（
comp.lang.pythonより、2000年7月26日）—— Alex Martelli
この章では、「11章 Pythonicなオブジェクト」のVector2dを大きくステップアップさせて、多次元のVectorクラスを作成します。このVectorは、Pythonで標準のイミュータブルなフラットシーケンスと同じようにふるまいます。浮動小数点数の要素から構成され、最終的には以下の機能をすべて備えることになります。
- シーケンスでの基本的なプロトコル（
__len__や__getitem__） - 多数の項目を持つインスタンスの安全な表現
- スライシングの適切なサポート、新しい
Vectorインスタンスの生成 - 全要素の値を考慮したハッシュコードの計算
- 書式指定の言語の拡張
シーケンス型ではあまり行われていませんが、Vector2dでの読み取り専用プロパティの代替として、__getattr__を利用した属性への動的なアクセスも実装します。
コードを中心に紹介しつつ、その合間に非公式なインターフェースとしてのプロトコルという概念について議論してゆきます。プロトコルとダックタイピングの関係や、これらが独自クラスを作成する際にもたらす意味も明らかにします。
12.1 第2版での変更点
大きな変更はありませんが、「12.4 プロトコルとダックタイピング」の終わり近くのノート記事としてtyping.Protocolに関する簡単な紹介を追加しました。 ...
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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.