Question

我正在编写ROS程序并使用catkin_make编译/链接。在头文件中，我已经使用虚方法定义了一个类。然后我创建了两个子类并实现了虚方法。

class Data {
  public:
    // TODO change to getter/setter when more CPU power
    // becomes available
    Data(){}
    Data(int8_t state_, ros::Time stamp_) :
      state(state_), stamp(stamp_){}
    int8_t state,type;
    ros::Time stamp;
    virtual float* get_data();
};

class GyroData : public Data {
  public:
    GyroData(const GyroData &other) :
      Data(other.state,other.stamp) {
      for (int i=0; i<RDR_LEN;i++) {
        data[i]=other.data[i];
      }
    }
    GyroData();
    float* get_data();
    float data[RDR_LEN]; // Data stored as rdr
};
// Usage:
//    GyroData gd = new GyroData();
//    gd->stamp = ros::Time::now();
//    delete gd;


// TODO Be absolutely sure that there are no memory leaks upon
// assigning and destroying map array
class MapData : public Data {
  public:
    MapData(const MapData &other) :
      Data(other.state,other.stamp),len(other.len) {
      data = new float[len];
      for (int i=0;i<len;i++) {
        data[i]=*other.data; 
      }
    }
    MapData(int16_t l): len(l) { data = new float[len];}
    MapData();
    float* get_data();
    void free_data();
    int16_t len;
    float *data; //FIXME change type once decided
};

虚拟方法在cpp文件中定义如下：

float* Data::get_data() {}

我认为没有任何回报是好的，但我会收到警告。我尝试在另一个文件中使用这些类（包括正确的头文件）。变量声明如下：

  GyroData *px4_r,*px4_r_tmp,*gyro_r,*gyro_r_tmp;
  MapData *boundary,*boundary_tmp,*obstacle,
        *obstacle_tmp,*target,*target_tmp;

这会导致文件无法正确链接。运行catkin_make后，在链接

期间收到错误

undefined reference to vtable for Data
undefined reference to vtable for GyroData
undefined reference to vtable for MapData

为什么此程序无法正确链接？

编辑：

catkin_make错误：

CMakeFiles/localizer.dir/src/localizer.cpp.o: In function `Localizer::Localizer()':
localizer.cpp:(.text+0x33d): undefined reference to `GyroData::GyroData()'
localizer.cpp:(.text+0x360): undefined reference to `GyroData::GyroData()'
CMakeFiles/localizer.dir/src/localizer.cpp.o: In function `Data::Data()':
localizer.cpp:(.text._ZN4DataC2Ev[_ZN4DataC5Ev]+0x13): undefined reference to `vtable for Data'
CMakeFiles/localizer.dir/src/localizer.cpp.o: In function `Data::Data(signed char, ros::Time)':
localizer.cpp:(.text._ZN4DataC2EaN3ros4TimeE[_ZN4DataC5EaN3ros4TimeE]+0x18): undefined reference to `vtable for Data'
CMakeFiles/localizer.dir/src/localizer.cpp.o: In function `GyroData::GyroData(GyroData const&)':
localizer.cpp:(.text._ZN8GyroDataC2ERKS_[_ZN8GyroDataC5ERKS_]+0x4c): undefined reference to `vtable for GyroData'
CMakeFiles/localizer.dir/src/localizer.cpp.o: In function `MapData::MapData(MapData const&)':
localizer.cpp:(.text._ZN7MapDataC2ERKS_[_ZN7MapDataC5ERKS_]+0x4d): undefined reference to `vtable for MapData'
localizer.cpp:(.text._ZN7MapDataC2ERKS_[_ZN7MapDataC5ERKS_]+0xe2): undefined reference to `Data::~Data()'
CMakeFiles/localizer.dir/src/localizer.cpp.o: In function `MapData::MapData(short)':
localizer.cpp:(.text._ZN7MapDataC2Es[_ZN7MapDataC5Es]+0x26): undefined reference to `vtable for MapData'
localizer.cpp:(.text._ZN7MapDataC2Es[_ZN7MapDataC5Es]+0x7b): undefined reference to `Data::~Data()'
collect2: error: ld returned 1 exit status
make[2]: *** [/home/eric/Documents/AMAV/turtle/devel/lib/terp/localizer] Error 1
make[1]: *** [terp/CMakeFiles/localizer.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....

编辑2：数据和子类的实现：

#include "terp/state_machine.h"

using namespace std;

// Only implemented so that function is not purely virtual
Data::~Data() {}

// Only implemented so that function is not purely virtual
float* Data::get_data() {}

float* GyroData::get_data() {
  return data;
}

GyroData::GyroData() {
  for (int i=0;i<RDR_LEN) {
    data[i]=0;
  }
}

GyroData::~GyroData() {}

float* MapData::get_data() {
  return data;
}

MapData::MapData() {
  len=1;
  data = new float[len];
  for (int i=0;i<len;i++) {
    data[i]=0;
  }
}

MapData::~MapData(){}

void MapData::free_data(MapData d) {
  free(d->map);
  delete d[];
}

使用虚方法对类中的vtable进行未定义的引用

0 个答案: