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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9.1
非同期に初期化されるモジュールの
require
299
ルをサポートするようにデザインされた
DI
コンテナを使えば、こういった問題は緩和されます。
しかし、これから見ていくように、モジュールを依存対象の初期化状態から簡単に分離できる
3
番目
の選択肢があるのです。
9.1.2
初期化前キュー
依存対象の初期化状態からモジュールを分離する単純なパターンとして、キューとコマンドパター
ンを利用する方法があります。考え方としては、モジュールの初期化が済んでいない状態で受け取っ
た命令を保存しておき、初期化が完了したら即座に実行するというわけです。
9.1.2.1
非同期に初期化されるモジュールの実装
この単純だが効果的な技法の実例として、小さなテストアプリを作成しましょう。手の込んだことは
何もしない、上の仮定を検証するためだけのものです。最初に、
asyncModule.js
という名前の、非
同期に初期化されるモジュー
ルを作成します（
02_async_init_queues
）。
const asyncModule = module.exports;
asyncModule.initialized = false;
asyncModule.initialize = callback => {
setTimeout(function() {
asyncModule.initialized = true;
callback();
}, 10000);
};
asyncModule.tellMeSomething = callback ...
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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.