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
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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.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.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.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.
項目 15：可能な場面では常に constexpr を用いる
｜
99
ることを意味するのです10！ さらに、コンパイル時処理と実行時処理の従来の厳密な境界は曖昧に
なり、また従来は実行時に行われていた一部の算出をコンパイル時処理に移行できることも意味し
ます。移行できるコード量が増えるほど、ソフトウェアの実行は高速化できます（コンパイル時間
は延びるけれど）。
C++11 では、Point のメンバ関数 setX と setY を constexpr と宣言できません。その原因で
ある制約は 2 つあります。1 つ目は、setX、setY がオブジェクトを変更するのに対し、C++11 の
constexpr メンバ関数は暗黙に const になることにあります。2 つ目は、setX、setY の戻り型が
void であるのに対し、C++11 では void をリテラル型としていないことです。C++14 ではこの 2 つ
の制約を解除しており、Point のセッタでも constexpr と宣言できます。
class Point {
public:
…
constexpr void setX(double newX) noexcept // C++14
{ x = newX; }
constexpr void setY(double newY) noexcept // C++14
{ y = newY; }
…
};
上例を用いると次のような関数も記述できます。
// return reflection of p with ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.