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 2：auto の型推論を理解する
｜
11
さて、ここまでで auto に関するテンプレートの型推論規則を学びました。初めに述べたように
型推論規則はきわめて直観的です。ほとんどの場合は直観的に理解できます。特別な注意が必要な
のは泥水をかき回すようなユニヴァーサル参照の型を推論する際の左辺値です。また、配列と関数
がポインタに成り下がる規則がさらにかき回して濁りが増します。コンパイラの胸ぐらをつかみ、
「お前が推論する型を吐け！」と怒鳴りつけたくなることもあるかもしれません。そんな時は項目 4
を読んでください。コンパイラがそう動作するよう上手くおだてるための項目です。
重要ポイント
•
テンプレートの型推論時には、参照実引数は参照とは扱われない。すなわち参照性は無視さ
れる。
•
ユニヴァーサル参照仮引数の型を推論する際には、左辺値実引数を特別扱いする。
•
値渡しの仮引数の型を推論する際には、const および／または volatile 実引数は非 const、
非 volatile と扱われる。
•
参照を初期化するものでなければ、配列または関数実引数はテンプレートの型推論時にポイ
ンタに成り下がる。
項目 2：auto の型推論を理解する
項目 1 のテンプレートの型推論を読んでいれば、auto の型推論についてもすでにほぼすべてを把
握していることになります。やや奇異にも見える一点だけを除き、auto の型推論はテンプレート
の型推論と同一です。しかしそんなことが可能でしょうか？ テンプレートの型推論ではテン ...
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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.