иерархия классов

#include <iostream>
#include <string>
#include <memory>
 
class Control {
};
 
class VisualControl : public Control {
 public:
  virtual void draw() = 0;
};
 
class Button : public VisualControl {
 public:
  Button(const std::string &caption) : caption_(caption) {}
  const std::string &getCaption() const { return caption_; }
 private:
  std::string caption_;
};
 
class WinButton : public Button {
 public:
  WinButton(const std::string &caption) : Button(caption) {}
  virtual void draw() {
    std::cout << "A windows button is drawed: '" << getCaption() << "'" << std::endl;
  }
};
 
class LinuxButton : public Button {
 public:
  LinuxButton(const std::string &caption) : Button(caption) {}
  virtual void draw() {
    std::cout << "A linux button is drawed: '" << getCaption() << "'" << std::endl;
  }
};
 
class Label : public VisualControl {
 public:
  Label(const std::string &label) : label_(label) {}
  const std::string &getLabel() const { return label_; }
 private:
  std::string label_;
};
 
class WinLabel : public Label {
 public:
  WinLabel(const std::string &label) : Label(label) {}
  virtual void draw() {
    std::cout << "A windows label is drawed. '" << getLabel() << "'" <<  std::endl;
  }
};
 
class LinuxLabel : public Label {
 public:
  LinuxLabel(const std::string &label) : Label(label) {}
  virtual void draw() {
    std::cout << "A linux label is drawed. '" << getLabel() << "'" <<  std::endl;
  }
};
 
class GUIFactory {
 public:
  virtual Button *createButton(const std::string &caption) = 0;
  virtual Label *createLabel(const std::string &label) = 0;
};
 
class WinFactory : public GUIFactory {
 public:
  virtual Button *createButton(const std::string &caption) {
    return new WinButton(caption);
  }
  virtual Label *createLabel(const std::string &label) {
    return new WinLabel(label);
  }
};
 
class LinuxFactory : public GUIFactory {
 public:
  virtual Button *createButton(const std::string &caption) {
    return new LinuxButton(caption);
  }
  virtual Label *createLabel(const std::string &label) {
    return new LinuxLabel(label);
  }
};
 
enum OSType {
  OSLinux,
  OSWindows
};
 
GUIFactory *createGUIFactory(OSType osType) {
  if (osType == OSLinux)
    return new LinuxFactory();
  if (osType == OSWindows)
    return new WinFactory();
  return NULL;
};
 
int main(int argc, char *argv[]) {
  OSType osType = OSLinux;
  std::auto_ptr<GUIFactory> guiFactory(createGUIFactory(osType));
  std::auto_ptr<VisualControl> label(guiFactory->createLabel("Information label."));
  std::auto_ptr<VisualControl> button(guiFactory->createButton("OK"));
  label->draw();
  button->draw();
}