opencv cv :: Ptr的动态强制转换

Question

I am currently implementing different opencv machine learning tools in c++ in the same class. Therefore I have the problem of downcasting pointers of the superclass cv::ml::StatModel to the subclass cv::ml::SVM (for example).

In online tutorials one usually finds the implementation of opencv classifiers like this:

cv::Ptr<cv::ml::SVM> classifier = cv::ml::SVM::create();

What I want to do is a dynamic cast in the class constructor. This is part of my class variables:

class Classifier{
private:
    cv::Ptr<cv::ml::StatModel> classifier;
    cv::Ptr<cv::ml::SVM> SVM;
//... followed by more code };

And in my constructor:

Classifier::Classifier(const char* filename, cv::ml::SVM& svm){
    bool load = Classifier::getData(filename);
    if (load==0){
        cout << "Error opening file!" << endl;
    }
    else{
        classifier = &svm;
        //Here I want to do something linke this, just with cv::Ptr:
        //the following line gives compiler errors because c++ does not know that cv::Ptr is a pointer...
        SVM = dynamic_cast<cv::ml::SVM*>(classifier); 
        Classifier::setUpSVM();
    }
}

Does anyone know if opencv provides an alternative to dynamic_cast<T>() for cv::Ptr ? Or alternatively has experience with not using the opencv pointers, but instead "normal" c++ pointers to use the machine learning API? I am wondering if I will run into problems with this implementation, because common practice seems to be using the opencv cv::Ptr class.

Answer 1

Yes, there is an openCV alternative of dynamic_cast<T>() written specifically for cv::Ptr . It's called... dynamicCast() :D There are also analogical alternatives to const cast and static cast for that matter.