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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604
14
章
Flyweight
パターン
Flyweight
パターン
クラスの1つのインスタンスを使って多数の「仮想インスタンス」を提
供できる場合には、Flyweightパターンを使いましょう。
シナリオ
新しい景観設計アプリケーションで、木をオブジェクトとして加えたいとします。こ
のアプリケーションでは、木には
X-Y
座標の位置があり、樹齢に応じて動的に描写され
ますが、実際にはあまり機能しません。しかし、ユーザは自分の家の景観設計の一部と
して数多くの木を配置したいと考えるかもしれません。以下の図のようなものです。
大口顧客のジレンマ
これまで何ヶ月も売り込みをかけてきた重要な顧客がいま
す。この顧客はあなたのアプリケーションを
1,000
セット購入
する予定で、そのソフトウェアを使って計画中の広大なコミュ
ニティ用の景観設計を行おうとしています。あなたのソフト
ウェアを
1
週間ほど使ってみたところ、この顧客は広大な林を
作ろうとするとアプリケーションが重くなると不満を漏らし
ています。
木
木
木
木
木
木
木
家
Tree
インスタンスは自身の
状態を保持します。
Tree
xCoord
yCoord
age
display() {
// X-Y
座標と複雑な
//
樹齢関連の
//
計算を使う
}
you are here
605
14 ...
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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.