小编Rex*_*ide的帖子

尝试std::bind()使用以下代码获取函数对象：

driver_manager driverManager();

std::function<void(mqtt::const_message_ptr,
mqtt::async_client*,callback*,sql::Driver*)> fn = std::bind(&driver_manager::test_callback, &driverManager, std::placeholders::_1, 
std::placeholders::_2, std::placeholders::_3, std::placeholders::_4);

结果出错：

错误：从'std::_Bind_helper<false, void (driver_manager::*)(std::shared_ptr<const mqtt::message>, mqtt::async_client*, callback*, sql::Driver*), driver_manager ( *)()、const std::_Placeholder<1>&、const std::_Placeholder<2>&、const std::_Placeholder<3>&、const std::_Placeholder<4>&>::type'非标量类型 'std::function<void(std::shared_ptr<const mqtt::message>, mqtt::async_client*, callback*, sql::Driver*)>' 请求

几个小时以来，我一直试图找出问题所在，这段代码有什么问题？

编辑

driver_manager.hpp

class driver_manager{
public:
    driver_manager();
    void test_callback(mqtt::const_message_ptr, mqtt::async_client*,callback*,sql::Driver*);
};

driver_manager.cpp

driver_manager::driver_manager(){

}

void driver_manager::test_callback(mqtt::const_message_ptr msg, mqtt::async_client *client, callback *cb, sql::Driver *driver){
    std::cout << "Callback triggered" << std::endl;
}