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
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,
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.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.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.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.
160
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
ticker
のオブジェクトは、他のイベント発生クラスをもとにしたオブジェクトと同じように使え、
メソッド
on
を使えばいくつでもリスナーをアタッチできるのですが、この例では、メソッド
emit
を使
おうとするとエラー「
TypeError: ticker.emit is not a function
」が引き起こされてコード
は失敗します。
この例は公開コンストラクタのパターンの使い方を示すのにとても役立っていますが、こ
のイベントエミッタの読み出し専用機能の堅牢さは完璧ではなく、回避する方法がいく
つかあります。たとえば、次のようにオリジナルの
emit
のプロトタイプを直接使えば、
ticker
のインスタンスにイベントを発生させることができます。
require('events').prototype.emit.call(ticker, 'someEvent', {});
6.2.2
実践での利用
このパターンはとても興味深いもので賢くできていますが、
Promise
のコンストラクタを除けば一
般的なユースケースを探すことは非常に困難です。
ただし、現在用いられているテンプレートパターンをよりよいものに置き換え、さまざまなストリー
ムのオブジェクトの振る舞いを記述可能にしようと、このパターンを適用したストリームの新たな仕
様が開発中であることは、
触れておくべきことでしょう。次のサイトを参照してください
−
https://
streams.spec.whatwg.org ...
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,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.