Question

I am trying to create a functor like so:

struct STFRandomTreeFunction
{
    typedef double (*function_ptr)(const TrainingDataPoint& data, boost::unordered_map<std::string, cv::Mat>& preloaded_images);
};


struct STFRandomTreeFunctor
{
private:
    boost::unordered_map<std::string, cv::Mat> *image_cache;
    STFRandomTreeFunction::function_ptr function;
    std::string function_id;

public:
    STFRandomTreeFunctor(boost::unordered_map<std::string, cv::Mat>& cache, STFRandomTreeFunction::function_ptr function_ptr, std::string function_id){
        image_cache = &cache;
        this->function = function;
        this->function_id = function_id;
    }

    std::string get_function_id(){
        return function_id;
    }

    double operator()(const TrainingDataPoint& data_point){
        return function(data_point, *image_cache);
    }
};

And am trying to run the following code:

double something(const TrainingDataPoint& a, unordered_map<string, Mat>& cache){
    return 5;
}


int main(int argc, char* argv[]) {

    unordered_map<string, Mat> cache;

    STFRandomTreeFunctor functor = STFRandomTreeFunctor(cache, something, "id");

    TrainingDataPoint d = TrainingDataPoint(1,2,"", ImagePoint(1,2), ImagePoint(1,2), "");

    double value  = functor(d);

    cout << "Value is " << value << endl;
}

However, I get no output. It appears as though some exception is throwing however eclipse is not showing me one but just showing that the program has terminated.

Any ideas?

Answer 1

In the constructor of STFRandomTreeFunctor

this->function = function;

That’s self assignment. I assume you meant to do this:

this->function = function_ptr;