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
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13章インターフェース、プロトコル、ABC
実装に合わせるのではなく、インターフェースに合わせてプログラミングしましょう。
—— Gamma、Helm、Johnson、Vlissides
『First Principle of Object-Oriented Design』†1
[†1] 『Design Patterns: Elements of Reusable Object-Oriented Software』、イントロダクション（18ページ）
オブジェクト指向プログラミングの本質はインターフェースにあります。Pythonでの型を理解するための最善の方法は、「8.4 実行可能な操作が型を決める」でも述べた通り、その型が提供するメソッドつまりインターフェースを知ることです。
プログラミング言語によっては、インターフェースを定義し利用する方法が複数用意されている場合もあります。Python 3.8以降には4つの方法があり、これらを図示したのが図13-1の型マップです。簡単にまとめると、以下のようになります。
- ダックタイピング
- 初期からずっと、Pythonでの型に関するデフォルトのアプローチです。本書でも「1章 Pythonのデータモデル」以降で学んできました。
- グースタイピング
- Python 2.6で採用されたABC（抽象基底クラス）でのアプローチです。実行時に行われるABCへの型チェックに基づいています。この章での主なトピックです。
- 静的型付け
- CやJavaといった静的型付け言語における古典的なアプローチです。Python 3.5から
typingモジュールによってサポートされるようになりました。実際のチェックを行うのは、『PEP 484——Type Hints』（https://fpy.li/pep484 ...
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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.