成员函数指针错误，boost绑定

error with member function pointers, boost bind

本文关键字：boost 绑定 错误 函数 指针 成员      更新时间：2023-10-16

我在一个文件中编写了一个连接到服务器的客户端，没有任何类。这显然不是一种好的编程方式，所以当代码最终按照我想要的方式运行时，我用下面的client.h创建了myclient类:

    #include <boost/asio.hpp> 
    #include <boost/array.hpp> 
    #include <iostream> 
    #include <string> 
    #include "mtbf.h"
    #include <boost/date_time/posix_time/posix_time.hpp>
    class myclient
    {
    public:
    boost::asio::io_service io_service; 
    boost::asio::ip::tcp::resolver resolver; 
    boost::asio::ip::tcp::socket sock; 
    boost::array<char, 4096> buffer; 
    typedef boost::posix_time::time_duration duration_t;
    typedef boost::posix_time::ptime timestamp_t;
    std::vector<std::string> tokens;
    boost::system::error_code m_err_feedback;

            enum ConnectionState
        {
            WAIT_FOR_HEADER,
            WAIT_FOR_DATA,
            PACKET_COMPLETE
        };
    myclient(std::string port);
    private:
        void read_handler(const boost::system::error_code &ec, std::size_t bytes_transferred);
        void connect_handler(const boost::system::error_code &ec);
        void resolve_handler(const boost::system::error_code &ec, boost::asio::ip::tcp::resolver::iterator it);
    };

我不写client.cpp的完整代码，但这里是错误发生的地方(构造函数)

    myclient::myclient(std::string port):resolver(io_service),sock(io_service)
    {
        tcp::resolver::query query("127.0.0.1", port); 
        resolver.async_resolve(query, boost::bind(&myclient::resolve_handler, this)); 
        io_service.run(); 
    }

我是c++的新手，但我知道我需要一个boost::bind来调用

中成员函数的引用。
 resolver.async_resolve(query, boost::bind(&myclient::resolve_handler, this));

但不知何故，这不是很正确，我得到一个错误:

error   8   error C2298: 'return': Invalid procedure for an expression with pointer to memberfunction C:projektelibsboost_1_53_0-VC11boostbindmem_fn.hpp  342 1   client

编辑:谢谢你的回复，但似乎还有更多的错误。我是不是漏掉了什么小事?下面是client.cpp中的代码(我删除了read_handler中的实际算法，因为它不重要)

    #include "client.h"
    using boost::asio::ip::tcp;
    myclient::myclient(std::string port):resolver(io_service),sock(io_service)
    {
        tcp::resolver::query query("127.0.0.1", port); 
        resolver.async_resolve(query, boost::bind(&myclient::resolve_handler, this,boost::asio::placeholders::error,boost::asio::placeholders::iterator)); 
        io_service.run(); 
    }
    void myclient::read_handler(const boost::system::error_code &ec, std::size_t bytes_transferred) 
    { 
    .
    .
    .

    } 
    void myclient::connect_handler(const boost::system::error_code &ec) 
    { 
      if (!ec) 
      { 
        sock.async_read_some(boost::asio::buffer(buffer), boost::bind(&myclient::read_handler, this,&ec)); 
      } 
    } 
    void myclient::resolve_handler(const boost::system::error_code &ec, boost::asio::ip::tcp::resolver::iterator it) 
    { 
      if (!ec) 
      { 
        sock.async_connect(*it, boost::bind(&myclient::connect_handler, this, &ec, it)); 
      } 
    }
使用

，我得到如下错误:

error   2   error C2825: "F": must be a class or namespace "::".    C:projektelibsboost_1_53_0-VC11boostbindbind.hpp  69  1   client
error   3   error C2039: 'result_type': is not an element of '`global namespace''   C:projektelibsboost_1_53_0-VC11boostbindbind.hpp  69  1   client

您忘记了resolve_handler参数的占位符:

boost::bind(&myclient::resolve_handler, this,
    boost::asio::placeholders::error, 
    boost::asio::placeholders::iterator)
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