为什么将std :: swap移至< utility> ;？ [英] Why was std::swap moved to <utility>?
问题描述
为什么将 std :: swap 移到C ++ 11的< utility> 标头中？
Why has std::swap been moved to the <utility> header for C++11?
N3290 C.2.7说：
N3290 C.2.7 says:
17.6.3.2
17.6.3.2
对原始功能的影响：函数交换移至其他标头
Effect on original feature: Function swap moved to a different header
理论上：删除对<$ c $的依赖c>< algorithm> 进行交换。
Rationale: Remove dependency on <algorithm>for swap.
对原始功能的影响：有效的C ++ 2003代码已编译，希望进行交换放在< algorithm> 中可能必须改为包含< utility> 。
Effect on original feature: Valid C++ 2003 code that has been compiled expecting swap to be in <algorithm> may have to instead include <utility>.
我听不懂粗体部分。
推荐答案
委员会希望允许您使用 swap（），而不会对大型且更复杂的< algorithm> 头文件引入编译时依赖性。由于 swap（）的使用如此广泛，因此让您以尽可能少的额外负担来拉入它的定义是很有意义的。对于通常不需要< algorithm> 的文件，这通常会缩短文件的编译时间。它的新家允许使用它而不会带来不必要的开销。
The committee wanted to allow you to use swap() without introducing a compile-time dependency on the large and more complex <algorithm> header file. Because swap() is so widely used, it makes sense to let you pull in its definition with as little additional baggage as possible; this will generally lead to faster compile times for files that don't otherwise need <algorithm>. Its new home allows it to be used without introducing unneeded overhead.
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