如何重载std :: swap() [英] How to overload std::swap()
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问题描述
std :: swap()
被许多std容器使用(例如 std :: list
std::swap()
is used by many std containers (such as std::list
and std::vector
) during sorting and even assignment.
但是,交换的std实现方法是code> std :: vector
因此,通过重载 std ::可以获得更高的效率swap()
使用自定义类型特定实现。但是如何实现它,所以它将被std容器使用?
Thus efficiency can be gained by overloading std::swap()
with a custom type specific implementation. But how can you implement it so it will be used by the std containers?
推荐答案
正确的方式重载交换是写它在与要交换的相同的命名空间中,以便可以通过参数相关查找(ADL)找到它。一个特别容易做的事是:
The right way to overload swap is to write it in the same namespace as what you're swapping, so that it can be found via argument-dependent lookup (ADL). One particularly easy thing to do is:
class X
{
// ...
friend void swap(X& a, X& b)
{
using std::swap; // bring in swap for built-in types
swap(a.base1, b.base1);
swap(a.base2, b.base2);
// ...
swap(a.member1, b.member1);
swap(a.member2, b.member2);
// ...
}
};
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