September 2014
Intermediate to advanced
336 pages
7h 53m
Japanese
Content preview from アンダースタンディング コンピュテーション ―単純な機械から不可能なプログラムまで
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6
1
章
Ruby
ひとめぐり
ソッドを実行させるメッセージを受け取るオブジェクトになります。したがって、オブジェクトのメ
ソッド内では、明示的に参照しなくても同じオブジェクトにメッセージが送れるのです。
>>
def o.add_twice(x, y)
add(x, y) + add(x, y)
end
=> nil
>>
o.add_twice(2, 3)
=> 10
#add_twice
メソッドの内部では、
o.add(x, y)
の代わりに
add(x, y)
と書くことで、
add
メッ
セージを
o
に送れることに注意しましょう。なぜなら、
o
は
add_twice
メッセージが送られたオブ
ジェクトだからです。
メソッド定義の外部では、現在のオブジェクトは
main
と呼ばれる特別なトップレベルオブジェクト
になります。レシーバを指定していないメッセージはすべて、この
main
オブジェクトに送られます。
同様に、オブジェクトを指定していないメソッド定義はすべて、この
main
オブジェクト経由で使えま
す。
>>
def multiply(a, b)
a
*
b
end
=> nil
>>
multiply(2, 3)
=> 6
1.5
クラスとモジュール
メソッド定義を複数のオブジェクトで共有できると便利です。Rubyでは、クラス（class）内にメ
ソッドを定義して、そのクラスに
new
メッセージを送ることによって、新しいオブジェクトを生成する
ことができます。生成されて返ってくるオブジェクトは、そのクラスのインスタンス（instance） ...
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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.