Boost 如何获取错误对象？在截止时间计时器中使用成员函数时

我使用boost:：asio:：deadline\u计时器，使用成员函数作为处理程序（回调函数）

如果取消计时器，如何在print（）成员函数中获取错误对象

class printer
{
public:
    printer(boost::asio::io_service& io)
        : timer_(io, boost::posix_time::seconds(1)),
          count_(0)
    {
        timer_.async_wait(boost::bind(&printer::print, this));
    }
    ~printer()
    {
        std::cout << "Final count is " << count_ << "\n";
    }
    void print()
    {
        if (count_ < 5)
        {
            std::cout << count_ << "\n";
            ++count_;

            timer_.expires_at(timer_.expires_at() + boost::posix_time::seconds(1));
            timer_.async_wait(boost::bind(&printer::print, this));
        }
    }

private:
    boost::asio::deadline_timer timer_;
    int count_;
};

int main()
{
    boost::asio::io_service io;
    printer p(io);
    io.run();

    return 0;
}

---

只要方法签名匹配，就应该没有问题：

void print(boost::system::error_code const ec)

// and

boost::bind(&printer::print, this, boost::asio::placeholders::error)

看到它了吗

#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <iostream>

class printer
{
public:
    printer(boost::asio::io_service& io)
        : timer_(io, boost::posix_time::seconds(1)),
          count_(0)
    {
        timer_.async_wait(boost::bind(&printer::print, this, boost::asio::placeholders::error));
    }
    ~printer()
    {
        std::cout << "Final count is " << count_ << "\n";
    }

    void print(boost::system::error_code const ec)
    {
        if (ec)
            std::cout << "Error: " << ec.message() << "\n";
        if (count_ < 5)
        {
            std::cout << count_ << "\n";
            ++count_;

            timer_.expires_at(timer_.expires_at() + boost::posix_time::seconds(1));
            timer_.async_wait(boost::bind(&printer::print, this, boost::asio::placeholders::error));
        }
    }

private:
    boost::asio::deadline_timer timer_;
    int count_;
};

int main()
{
    boost::asio::io_service io;
    printer p(io);
    io.run();
}

#包括
#包括
#包括
类打印机
{
公众：
打印机（boost:：asio:：io\U服务和io）
：timer_（io，boost:：posix_time:：seconds（1）），
计数（0）
{
计时器异步等待（boost:：bind（&printer:：print，this，boost:：asio:：placeholders:：error））；
}
~printer（）
{
std:：cout您没有提供编译器错误消息。这很奇怪，因为您对此有疑问。@sehe谢谢：）我写了一个错误的成员函数签名，比如void print（boost:：system:：error\u code ec）。const关键字被省略。而且，我下次必须写错误消息。
#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <iostream>

class printer
{
public:
    printer(boost::asio::io_service& io)
        : timer_(io, boost::posix_time::seconds(1)),
          count_(0)
    {
        timer_.async_wait(boost::bind(&printer::print, this, boost::asio::placeholders::error));
    }
    ~printer()
    {
        std::cout << "Final count is " << count_ << "\n";
    }

    void print(boost::system::error_code const ec)
    {
        if (ec)
            std::cout << "Error: " << ec.message() << "\n";
        if (count_ < 5)
        {
            std::cout << count_ << "\n";
            ++count_;

            timer_.expires_at(timer_.expires_at() + boost::posix_time::seconds(1));
            timer_.async_wait(boost::bind(&printer::print, this, boost::asio::placeholders::error));
        }
    }

private:
    boost::asio::deadline_timer timer_;
    int count_;
};

int main()
{
    boost::asio::io_service io;
    printer p(io);
    io.run();
}