元组不是按顺序构建的？ [英] Tuple isn't being constructed in order?

问题描述

// Example program
#include <iostream>
#include <tuple>

struct X {
    X(int) { std::cout << "X constructor\n"; }
};
struct Y {
    Y(int) { std::cout << "Y constructor\n"; }
};

int main()
{
    std::tuple<X,Y> t(1,2);
}

输出：

Y constructor
X constructor

我认为标准保证了顺序元组元素是在A，B，...，Y，Z？中构造的。

This doesn't seem correct... I thought the standard guaranteed the order tuple elements were constructed in: A, B, ..., Y, Z?

推荐答案

std :: tuple 施工顺序目前未指定。

有关其订单具体决定的提案已经提交给委员会，但在此之前不应依赖该订单。

A proposal for a concrete decision on its order has been submitted to the committee, but until then the order should not be relied on.

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