May 2019
Intermediate to advanced
464 pages
9h 22m
Japanese
Content preview from Node.jsデザインパターン 第2版
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148
6
章 オブジェクト指向デザインパターンの
Node.js
への適用
この章では、もっとも重要な
GoF
デザインパターンのいくつかがどのように
Node
（およびその哲学）
に応用できるかを見ることで、パターンの重要性を別の観点から再発見したいと思います。従来型の
パターンに混じって、
JavaScript
の世界で生まれた「従来型とは少し違う」パターンもいくつか見ていき
ます。
この章で検討するデザインパターンは次のとおりです。
●
ファクトリ
●
公
リビーリング
開コンストラクタ
●
プロキシ
●
デコレータ
●
アダプタ
●
ストラテジー
●
ステート
●
テンプレート
●
ミドルウェア
●
コマンド
この章では
JavaScript
の継承についてある程度の知識があることを前提として説明しま
す。さらに、パターンの実装はクラスベースのものだけでなく、オブジェクトベースのも
のや関数ベースのものもあります。このため、この章では標準
UML
を使った説明ではな
く、より一般的で直感的な図を使います。
6.1
ファクトリ
まず手始めに、もっとも単純で
Node
でもっともよく使われるデザインパターンである「ファクトリ」
を取り上げましょう。
6.1.1
オブジェクト生成の一般的インタフェース
JavaScript
においては、純粋なオブジェクト指向デザインより関数ベースの定義のほうが、単純で使
いやすく、「露出部分最小化」の原則に合致するために好まれることが多いということは、既に強調し
ました。これは、オブジェクトの新しいインスタンスを生成する
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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.