是什么给了 std::future 一些共享状态
What gives a std::future some shared state
A std::future has a std::future::valid method, which indicates whether the future object refers to some shared state. None of the constructors construct a future object that refers to shared state (except the move constructor, which can move the shared state from one future object to another). All the methods of the class (get, wait, wait_for and wait_until 要求未来对象具有共享状态作为先决条件（如果 valid() == false 它们具有未定义的行为）。 std::future 如何获得一些 共享状态 并变得有用？
您通常不会单独使用 std::future；您将它与 std::promise. The std::promise constructors set up some shared state. You can then use the std::promise::get_future() 方法一起使用以获得引用 共享状态 .
的 std::future
A std::future has a std::future::valid method, which indicates whether the future object refers to some shared state. None of the constructors construct a future object that refers to shared state (except the move constructor, which can move the shared state from one future object to another). All the methods of the class (get, wait, wait_for and wait_until 要求未来对象具有共享状态作为先决条件（如果 valid() == false 它们具有未定义的行为）。 std::future 如何获得一些 共享状态 并变得有用？
您通常不会单独使用 std::future；您将它与 std::promise. The std::promise constructors set up some shared state. You can then use the std::promise::get_future() 方法一起使用以获得引用 共享状态 .
std::future