在集合之间移动ʻunique_ptr` [英] Move `unique_ptr`s between sets

问题描述

我有两个集合和一个元素 a 的迭代器：

I have two sets and an iterator to an element of a:

set<unique_ptr<X>> a, b;
set<unique_ptr<X>>::iterator iter = find something in a;

我想删除 iter 从 a 中插入到 b 中。可能吗？

I would like to remove the element pointed by iter from a and insert it into b. Is it possible? How?

推荐答案

好吧，我怀疑没有正常的方法。但是总会有一个非正常的：)
您可以执行以下操作：

Well, I suspect there is no normal way to do it. But there is always a non-normal one :) You can do the following:

auto tmp = const_cast<std::unique_ptr<std::string>&&>(*iter);
a.erase(iter);
b.insert(std::move(tmp));

好的，第一行违反了 set 不变，这很可怕，但据我所知这应该不是问题，因为在下一行，我们从集合中删除了这个邪恶节点。

Ok, the very first line violated set invariant and it is horrible but as far as I understand it should not be a problem since on the very next line we remove this evil node from the set.

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