C++ for循环中的向量push_back异步对象
我正在用 C++11 编写一个 for 循环，其中需要将异步对象推回到向量上。我想将对象初始化分为两个步骤：
std::vector<std::future<bool>> asyncThreads;
for (int i = 0; i < processorCount; i++) {
auto boundFunc = std::bind(&Foo::foo, this);
auto asyncThread = std::async(std::launch::async, boundFunc)
asyncThreads.push_back(asyncThread);
}
现在我确实意识到 boundFunc 和 asyncThread 对象在 for 循环结束时超出了范围（>push_back 函数应该复制/移动值），但是为什么直接在 push_back 调用 中声明对象可以工作呢？就像这样：
std::vector<std::future<bool>> asyncThreads;
for (int i = 0; i < processorCount; i++) {
asyncThreads.push_back(std::async(std::launch::async, std::bind(&Foo::foo, this)));
}
I was coding a for loop in C++11, where I needed to push back an async object onto a vector. I wanted to split the object initialization into two steps:
std::vector<std::future<bool>> asyncThreads;
for (int i = 0; i < processorCount; i++) {
auto boundFunc = std::bind(&Foo::foo, this);
auto asyncThread = std::async(std::launch::async, boundFunc)
asyncThreads.push_back(asyncThread);
}
Now I do realize that both boundFunc and asyncThread objects go out of scope at the end of the for loop (the push_back function should copy/move the values though), but then why does directly declaring the objects in the push_back call work? Like so:
std::vector<std::future<bool>> asyncThreads;
for (int i = 0; i < processorCount; i++) {
asyncThreads.push_back(std::async(std::launch::async, std::bind(&Foo::foo, this)));
}
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std::future对象不可复制，但可移动。因此，您必须对对象调用 move 将其推送到向量上。A
std::futureobject is not copyable, but moveable. So therefore, you must call move on the object to push it onto the vector.