September 2015
Intermediate to advanced
364 pages
10h 33m
Japanese
Content preview from Effective Modern C++ ―C++11/14プログラムを進化させる42項目
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項目 27：ユニヴァーサル参照をとるオーバロードの代替策を把握する
｜
187
SpecialPerson(const SpecialPerson& rhs) // copy ctor; calls
: Person(rhs) // base class
{ … } // forwarding ctor!
コピーコンストラクタ。基
底クラスの転送コンストラ
クタを呼び出す！
SpecialPerson(SpecialPerson&& rhs) // move ctor; calls
: Person(std::move(rhs)) // base class
{ … } // forwarding ctor!
};
ムーブコンストラクタ。基
底クラスの転送コンストラ
クタを呼び出す！
コメントにもあるように、派生クラスのコピー／ムーブコンストラクタは基底クラスのコピー／
ムーブコンストラクタを呼び出さず、基底クラスの完全転送コンストラクタを呼び出すのです！ そ
の理由を考えてみましょう。まず、派生クラスでは SpecialPerson 型の実引数を基底クラスへ渡し
ます。次に、Person のコンストラクタのテンプレートをインスタンス化し、オーバロードを解決し
ます。ここで、SpecialPerson をとる std::string コンストラクタなど存在しないため、最終的
にコンパイルできません。
ここまでで、ユニヴァーサル参照を仮引数にとるオーバロードとは、可能な限り避けるべきもの
であると納得されたことを願います。し ...
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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.