June 2022
Beginner to intermediate
672 pages
17h 23m
Japanese
Content preview from Head Firstデザインパターン 第2版 ―頭とからだで覚えるデザインパターンの基本
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Factory Method
パターンの定義
Factory Methodパターンはオブジェクトを作成するためのインタフェー
スを定義するが、どのクラスをインスタンス化するかについてはサブク
ラスに決定させる。
Factory Method
により、クラスはサブクラスにイン
スタンス化を委ねることができる。
ここでは、
Factory Method
パターンの正式な定義を紹介します。
他のファクトリと同様、
Factory Method
パターンは具象型のインスタンス化をカプセル化
する方法を備えています。以下のクラス図から、抽象
Creator
（作成者）クラスがオブジェク
トを作成するメソッド（「ファクトリメソッド」とも呼ばれます）を持つインタフェースを用
意していることがわかります。抽象
Creator
で実装する他のすべてのメソッドは、ファクトリ
メソッドで作成する製品（
Product
）に対して処理を行うように記述されます。実際にはサブ
クラスだけがファクトリメソッドを実装し、製品を作成します。
正式な定義にあるように、「
Factory Method
パターンはインスタンス化するクラスをサブク
ラスに決定させる」と開発者が言っているのをよく耳にするでしょう。
Creator
クラスは作成
する実際の製品に関する知識を持つことなく記述されているので、「決定」と言っているのは
このパターンによって実行時にサブクラス自体が決定できるからではなく、むしろ実際には
どのサブクラスを使って製品を作成するかで決まるからです。
Product ...
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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.