February 2013
Intermediate to advanced
380 pages
7h 45m
Japanese
Content preview from Nodeクックブック
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314
9 章 自分の Node モジュールを作成する
stat
関数以外の
Mp3dat
オブジェクトプロパティを公開する必要がない場合は、もう
1
つの改良
アプローチとしてレシピ
9.3
のスクリプトを以下に書き換えます。
lib/index.js（書き換え前）
module.exports = Mp3dat();
lib/index.js（書き換え後）
exports.stat = function(f, cb) {
var m = Mp3dat();
return Mp3dat.prototype.stat.call(m, f, cb);
}
call
メソッドを使って、
Mp3dat
オブジェクトのスコープを
stat
メソッドに適用しています。
mp3dat
オブジェクトは以下のような内容になります。
{ stat: [Function] }
出力内容はレシピ
9.2
の状態に戻りましたが、内部的にはプロトタイプパターンを使った実装に
なっています。こちらのほうが少しだけ効率的です。
ミニレシピ
9.3.2
複数のモジュールインスタンスの生成を許可する
レシピ
9.3
で構築している
Mp3dat
はシングルトンです。
Mp3dat
モジュールを呼び出すと、初期
化済みの
Mp3dat
オブジェクトが返ってきます。したがって、このモジュールをどのファイルから
何回呼びだそうとも、常に同じオブジェクトにアクセスしていることになります。
この状態では、複数の
mp3dat.stat
メソッドを同時に実行しようとすると問題が起こります。
2
つの変数が同じオブジェクトを参照しているため ...
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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.