如何在类中创建DPMDetector对象？

Question

我喜欢在班上使用这个DPMDetector对象。

namespace cv
{

namespace dpm
{

/** @brief This is a C++ abstract class, it provides external user API to work with DPM.
 */
class CV_EXPORTS_W DPMDetector
{
public:

    struct CV_EXPORTS_W ObjectDetection
    {
        ObjectDetection();
        ObjectDetection( const Rect& rect, float score, int classID=-1 );
        Rect rect;
        float score;
        int classID;
    };

    virtual bool isEmpty() const = 0;

    /** @brief Find rectangular regions in the given image that are likely to contain objects of loaded classes
    (models) and corresponding confidence levels.
    @param image An image.
    @param objects The detections: rectangulars, scores and class IDs.
    */
    virtual void detect(cv::Mat &image, CV_OUT std::vector<ObjectDetection> &objects) = 0;

    /** @brief Return the class (model) names that were passed in constructor or method load or extracted from
    models filenames in those methods.
     */
    virtual std::vector<std::string> const& getClassNames() const = 0;

    /** @brief Return a count of loaded models (classes).
     */
    virtual size_t getClassCount() const = 0;

    /** @brief Load the trained models from given .xml files and return cv::Ptr\<DPMDetector\>.
    @param filenames A set of filenames storing the trained detectors (models). Each file contains one
    model. See examples of such files here `/opencv_extra/testdata/cv/dpm/VOC2007_Cascade/`.
    @param classNames A set of trained models names. If it's empty then the name of each model will be
    constructed from the name of file containing the model. E.g. the model stored in
    "/home/user/cat.xml" will get the name "cat".
     */
    static cv::Ptr<DPMDetector> create(std::vector<std::string> const &filenames,
            std::vector<std::string> const &classNames = std::vector<std::string>());

    virtual ~DPMDetector(){}
};

} // namespace dpm
} // namespace cv

我试过

class myClass{
private:
   DPMDetector *detector;//first approach
   cv::Ptr<DPMDetector> detector;//second approach
public:
  myClass();
  void fun1(void);
  void fun2(void);
}

fun1 and fun2 will use detector;

如果我喜欢

myClass::myClass(){
   detector->create(vector<string>(1, "inriaperson.xml"));//first approach
   detector = DPMDetector::create(vector<string>(1, "inriaperson.xml"));//second approach

}

对于第一种和第二种方法，我都有像

这样的错误

undefined reference to `cv::dpm::DPMDetector::create(std::vector<std::string, std::allocator<std::string> > const&, std::vector<std::string, std::allocator<std::string> > const&)'

如何创建DPMDetector对象以便fun1和fun2可以使用？