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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166
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
グ出力されているのがわかります。
6.3.4
現場でのプロキシ
−
関数フッキングと
AOP
プロキシにはさまざまな形式があるので、
Node
の中だけでなく、現場においてもかなりよく見ら
れるパターンになっています。実際、プロキシを簡単に作成できるようにしてくれるライブラリが数
個あり、そのほとんどでオブジェクト拡張が利用されています。開発コミュニティ内では、このパ
ターンは「関数フッキング」と呼ばれたり、ときには「アスペクト指向プログラミング（
aspect-oriented
programming
：
AOP
）」と呼ばれたりしますが、実際はプロキシの応用です。
AOP
ではライブラリを使っ
て開発者が特定のメソッドに実行前後のフッキングを設定できるようになっており、指定されたメソッ
ドの実行前後に独自のコードを実行できるようになっています。
プロキシは「ミドルウェア」と呼ばれることもあります。ミドルウェアパターン（この
章の後のほうで
扱います）の中に現れて、関数の入出力の前処理、後処理を可能にするからです。ときにはミドルウェ
アに似たパイプラインを使って同じメソッドに複数のフッキングを登録することもあります。
簡単に関数フッキングを実装できるようにするライブラリとして、
hooks
（
https://npmjs.org/
package/hooks
）、
hooker
（
https://npmjs.org/package/hooker
）、
meld
（
ht
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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.