C++将已删除的函数 std::unique_ptr 与基类一起使用

Question

我有一个向量或游戏对象。我必须为 c++11 编译

std::vector< std::unique_ptr<Game> > games_;

游戏是基类，定义如下

class Game {
public:
        Game(int id, const std::string& name)
                : id_(id), name_(name){}
        virtual ~Game(); 
        int play(int w);
        virtual void validate() = 0;
        int id_;
        std::string name_;
};

派生类只实现了 validate（） 方法。

现在我的经理类想要将"玩游戏"发布到线程池。像这样完成：

void Manager::playGames() {

        boost::asio::io_service ioService;
        std::unique_ptr<boost::asio::io_service::work> work( new boost::asio::io_service::work(ioService));
        boost::thread_group threadpool; //pool
        std::cout << "will start for " << playthreads_ << " threads and " << getTotalRequests() << "total requestsn";
        for (std::size_t i = 0; i < playthreads_; ++i)
                threadpool.create_thread(boost::bind(&boost::asio::io_service::run, &ioService));
        for ( std::size_t i=0; i < w_.size(); i++) {
                ioService.post(boost::bind(&Game::play, games_[i], 2));
        }    
        work.reset();
        threadpool.join_all();
        ioService.stop();
}

错误是

/home/manager.cpp: In member function ‘void Manager::playGames()’:
/home//manager.cpp:65:74: error: use of deleted function
 ‘std::unique_ptr<_Tp, _Dp>::unique_ptr(const std::unique_ptr<_Tp, _Dp>&)
 [with _Tp = Game; _Dp = std::default_delete<Game>]’ 
 ioService.post(boost::bind(&Game::play, games_[i], 2));
                                                                          ^
In file included from /opt/5.2/include/c++/5.2.0/memory:81:0,
                 from /home/manager.hpp:5,
                 from /home/manager.cpp:1: /opt/5.2/include/c++/5.2.0/bits/unique_ptr.h:356:7: note: declared
here
       unique_ptr(const unique_ptr&) = delete;

Answer 1

对于boost::bind(&Game::play, games_[i], 2)，games_[i]被复制到绑定，但std::unique_ptr不能复制。（它只能移动，但我认为将其移动到此处不符合要求。

您可以使用boost::ref来避免复制，例如

ioService.post(boost::bind(&Game::play, boost::ref(games_[i]), 2));