class PhotoRecognizer
{
 public:
    int perform_recogniton()
    {
        pPreProcessing->do_preprocessing();
        pFeatureExtractor->do_feature_extraction();
        pClassifier->do_classification()
     }

    boost::shared_ptr<PreProcessing> pPreProcessing;
    boost::shared_ptr<FeatureExtractor> pFeatureExtractor;
    boost::shared_ptr<Classifier> pClassifier;

}

class SVMClassifier: public Classifier
{
 public:
    void do_classification();

};

class MethodFactory
{
 public:
      MethodFactory(){};
        boost::shared_ptr<PreProcessing> pPreProcessing;
        boost::shared_ptr<FeatureExtractor> pFeatureExtractor;
        boost::shared_ptr<Classifier> pClassifier;

};
class Method1:public MethodFactory
{
  public:
     Method1():MethodFactory()
     {
          pPreProcessing.reset(new GaussianFiltering);
          pFeatureExtractor.reset(new FFTStatictis);
          pClassifier.reset(new SVMClassifier);

      }

};

class Method2:public MethodFactory
{
  public:
     Method1():MethodFactory()
     {
          pPreProcessing.reset(new MedianFiltering);
          pFeatureExtractor.reset(new WaveletStatictis);
          pClassifier.reset(new NearestNeighborClassifier);

      }

};



 class PhotoRecognizer
    {
     public:
        PhotoRecognizer(MethodFactory *p):pFactory(p)
        {
         }
        int perform_recogniton()
        {
            pFactory->pPreProcessing->do_preprocessing();
            pFactory->pFeatureExtractor->do_feature_extraction();
            pFactory->pClassifier->do_classification()
         }

       MethodFactory *pFactory;


    }

Method1 med;
PhotoRecognizer recogMethod1(&med);
med.perform_recognition()

enum RecMethod
{
  Method1, Method2

};

class PhotoRecognizer
{
public:
    PhotoRecognizer(RecMethod)
    {
       switch(RecMethod)
       {
          case Method1:
             pFactory.reset(new Method1());
             break;
           ...
         }
     }

    boost::shared_ptr<MethodFactory> pFactory;

};