c++之packaged_task和future实现异步效果

class CObject {
public:CObject(string str) :m_str(unique_ptr<string>(new string(str))) {cout << "构造函数" << endl;}~CObject() {if (m_str)cout << "析构函数: " << *m_str << " [" << this << "]" << endl;elsecout << "析构函数: (moved) [" << this << "]" << endl;}CObject(const CObject& obj) {m_str = make_unique<string>(*obj.m_str);cout << "拷贝构造函数" << endl;}CObject(CObject&& obj) noexcept {m_str = move(obj.m_str);cout << "移动构造函数" << endl;}CObject* show() {cout << "m_str=" << *m_str << endl;return this;}CObject* show_error() {cout << "this is error" << endl;return this;}void operator()(int num) {cout << "num=" << num << endl;}void update_str(char *str) {*m_str = string(str);}private:unique_ptr<string>m_str;};

调用:

		std::packaged_task<CObject(string)> task([](string str) {return CObject(str); });std::future<CObject> fut = task.get_future();std::thread t(std::move(task),"萧海");  // 任务交给线程执行CObject obj=move( fut.get());obj.show();t.join();