c++ - 如何使用 boost::bind 附加参数？

Question

我正在尝试使用 boost::bind 将另一个参数附加到 ROS 订阅者回调函数，但我不知道我的代码有什么问题:

这是回调函数签名:

void setDigitalOutputCallback(const std_msgs::Bool& cmd, int index);

在通常的 ROS 回调中，只有第一个 (cmd) 参数)。然后我尝试使用以下方法设置回调:

digitalOutputSub[i] = nh.subscribe(topicName, 1, boost::bind(setDigitalOutputCallback, _1, i));

示例代码:

#include "std_msgs/Bool.h"
#include "ros/ros.h"

void setDigitalOutputCallback(const std_msgs::Bool& cmd, int index) {

}

int main(int argc, char *argv[])
{
    ros::init(argc, argv, "blaster_driver");
    ros::NodeHandle nh;
    ros::Subscriber digitalOutputSub;
    std::string topicName = "test";
    int i = 1;
    digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));

    return 0;
}

编译器在那一行给出了很多错误，但我不明白那里出了什么问题:

test.cpp: In function ‘int main(int, char**)’: test.cpp:15:100: error: no matching function for call to ‘ros::NodeHandle::subscribe(const char*, int, boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >)’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:401:14: note: candidate: template<class M, class T> ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(M), T*, const ros::TransportHints&)    Subscriber subscribe(const std::string& topic, uint32_t queue_size, void(T::*fp)(M), T* obj,
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:401:14: note:   template argument deduction/substitution failed: test.cpp:15:100: note:   mismatched types ‘void (T::*)(M)’ and ‘boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:412:14: note: candidate: template<class M, class T> ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(M) const, T*, const ros::TransportHints&)    Subscriber subscribe(const std::string& topic, uint32_t queue_size, void(T::*fp)(M) const, T* obj,
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:412:14: note:   template argument deduction/substitution failed: test.cpp:15:100: note:   mismatched types ‘void (T::*)(M) const’ and ‘boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:464:14: note: candidate: template<class M, class T> ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(const boost::shared_ptr<const M>&), T*, const ros::TransportHints&)    Subscriber subscribe(const std::string& topic, uint32_t queue_size,
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:464:14: note:   template argument deduction/substitution failed: test.cpp:15:100: note:   mismatched types ‘void (T::*)(const boost::shared_ptr<const M>&)’ and ‘boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:474:14: note: candidate: template<class M, class T> ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(const boost::shared_ptr<const M>&) const, T*, const ros::TransportHints&)    Subscriber subscribe(const std::string& topic, uint32_t queue_size,
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:474:14: note:   template argument deduction/substitution failed: test.cpp:15:100: note:   mismatched types ‘void (T::*)(const boost::shared_ptr<const M>&) const’ and ‘boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:528:14: note: candidate: template<class M, class T> ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(M), const boost::shared_ptr<U>&, const ros::TransportHints&)    Subscriber subscribe(const std::string& topic, uint32_t queue_size, void(T::*fp)(M),
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:528:14: note:   template argument deduction/substitution failed: test.cpp:15:100: note:   mismatched types ‘void (T::*)(M)’ and ‘boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:539:14: note: candidate: template<class M, class T> ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(M) const, const boost::shared_ptr<U>&, const ros::TransportHints&)    Subscriber subscribe(const std::string& topic, uint32_t queue_size, void(T::*fp)(M) const,
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:539:14: note:   template argument deduction/substitution failed: test.cpp:15:100: note:   mismatched types ‘void (T::*)(M) const’ and ‘boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:593:14: note: candidate: template<class M, class T> ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(const boost::shared_ptr<const M>&), const boost::shared_ptr<U>&, const ros::TransportHints&)    Subscriber subscribe(const std::string& topic, uint32_t queue_size,
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:593:14: note:   template argument deduction/substitution failed: test.cpp:15:100: note:   mismatched types ‘void (T::*)(const boost::shared_ptr<const M>&)’ and ‘boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:604:14: note: candidate: template<class M, class T> ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (T::*)(const boost::shared_ptr<const M>&) const, const boost::shared_ptr<U>&, const ros::TransportHints&)    Subscriber subscribe(const std::string& topic, uint32_t queue_size,
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:604:14: note:   template argument deduction/substitution failed: test.cpp:15:100: note:   mismatched types ‘void (T::*)(const boost::shared_ptr<const M>&) const’ and ‘boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:655:14: note: candidate: template<class M> ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (*)(M), const ros::TransportHints&)    Subscriber subscribe(const std::string& topic, uint32_t queue_size, void(*fp)(M), const TransportHints& transport_hints = TransportHints())
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:655:14: note:   template argument deduction/substitution failed: test.cpp:15:100: note:   mismatched types ‘void (*)(M)’ and ‘boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:703:14: note: candidate: template<class M> ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, void (*)(const boost::shared_ptr<const M>&), const ros::TransportHints&)    Subscriber subscribe(const std::string& topic, uint32_t queue_size, void(*fp)(const boost::shared_ptr<M const>&), const TransportHints& transport_hints = TransportHints())
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:703:14: note:   template argument deduction/substitution failed: test.cpp:15:100: note:   mismatched types ‘void (*)(const boost::shared_ptr<const M>&)’ and ‘boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:749:14: note: candidate: template<class M> ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, const boost::function<void(const boost::shared_ptr<const M>&)>&, const VoidConstPtr&, const ros::TransportHints&)    Subscriber subscribe(const std::string& topic, uint32_t queue_size, const boost::function<void (const boost::shared_ptr<M const>&)>& callback,
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:749:14: note:   template argument deduction/substitution failed: test.cpp:15:100: note:   ‘boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >’ is not derived from ‘const boost::function<void(const boost::shared_ptr<const M>&)>’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:798:14: note: candidate: template<class M, class C> ros::Subscriber ros::NodeHandle::subscribe(const string&, uint32_t, const boost::function<void(C)>&, const VoidConstPtr&, const ros::TransportHints&)    Subscriber subscribe(const std::string& topic, uint32_t queue_size, const boost::function<void (C)>& callback,
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:798:14: note:   template argument deduction/substitution failed: test.cpp:15:100: note:   ‘boost::_bi::bind_t<void, void (*)(const std_msgs::Bool_<std::allocator<void> >&, int), boost::_bi::list2<boost::arg<1>, boost::_bi::value<int> > >’ is not derived from ‘const boost::function<void(C)>’   digitalOutputSub = nh.subscribe(topicName.c_str(), 1, boost::bind(setDigitalOutputCallback, _1, i));
                                                                                                    ^ In file included from /opt/ros/indigo/include/ros/ros.h:45:0,
                 from test.cpp:2: /opt/ros/indigo/include/ros/node_handle.h:835:14: note: candidate: ros::Subscriber ros::NodeHandle::subscribe(ros::SubscribeOptions&)    Subscriber subscribe(SubscribeOptions& ops);
              ^~~~~~~~~ /opt/ros/indigo/include/ros/node_handle.h:835:14: note:   candidate expects 1 argument, 3 provided

Answer 1

从文档来看，您似乎想使用以下重载:

Subscriber ros::NodeHandle::subscribe(
    const std::string & topic,
    uint32_t queue_size,
    const boost::function<void(C)> &    callback,
    const VoidConstPtr &    tracked_object = VoidConstPtr(),
    const TransportHints &  transport_hints = TransportHints() 
)

但是你没有正确的匹配，尝试创建你的 boost::function 作为变量:

boost::function<void (const std_msgs::Bool&)> f =
    boost::bind(setDigitalOutputCallback, _1, i);

digitalOutputSub = nh.subscribe(topicName.c_str(), 1, f);

不确定您是否不必指定模板参数:

digitalOutputSub = nh.subscribe<std_msgs::Bool>(topicName.c_str(), 1, f);