如何将boost :: bind对象存储为类成员？

Question

我正在编写一个使用的应用程序boost::asio.Asio async_receive(或async_read)总是使用boost::bind给出的回调对象显示:

boost::asio::async_read(socket_,
                        boost::asio::buffer(read_msg_.data(),
                                            chat_message::header_length),
                        boost::bind(&chat_session::handle_read_header,
                                    shared_from_this(),
                                    boost::asio::placeholders::error));

这非常好,但我不想在每次调用回调后重新创建绑定对象.相反,我想在我的类的构造函数中创建对象,并将其赋予async_receive.

问题是,我不知道如何将该对象声明为类成员.我所知道的只是汽车,它显然不会作为班级成员.

class Whatever
{
public:
    Whatever()
    {
        functor = boost::bind(&Whatever::Callback);
    }
private:
    void Callback()
    {
        boost::asio::async_read(socket_,
                        boost::asio::buffer(read_msg_.data(),
                                            chat_message::header_length),
                        functor);
    }

    ?? functor; // How do I declare this?
    ...
};

注意:这可能是过早优化,但我仍然想知道如何在没有auto的情况下声明绑定对象.

Answer 1

用途boost::function:

class Whatever
{
public:
    Whatever()
    {
        functor = boost::bind(
            &chat_session::handle_read_header,
            shared_from_this(),
            boost::asio::placeholders::error,
            boost::asio::placeholders::bytes_transferred
        );
        boost::asio::async_read(
            socket_,
            boost::asio::buffer(
               read_msg_.data(),
               chat_message::header_length
            ),
            functor
        );
    }
private:
    boost::function<void(const error_code, const size_t)> functor;
};

... 或类似的东西.