关于工厂模式的一些反思

//window.h



class window
{
  public:
     virtual ~window(){};//必须是虚函数

  public:
     virtual void set_titile(const char* title_) = 0;//纯虚函数
     virtual void set_background_color(int r_, int g_, int b_, int a_) = 0;
     virtual void set_size(int width_, int height_) = 0;
};
window* create_window();

//window.cpp


class linux_window
:public window
{
  public:
      ~win_window(){}
  public:
      void set_title(const char* title_){\\暂时不实现功能}
      void set_background_color(int r_, int g_, int b_, int a_){\\暂时不实现功能}
      void set_size(int width_, int height_){\\暂时不实现功能}
};
class android_window
:public window
{
  public:
      ~win_window(){}
  public:
      void set_title(const char* title_){\\暂时不实现功能}
      void set_background_color(int r_, int g_, int b_, int a_){\\暂时不实现功能}
      void set_size(int width_, int height_){\\暂时不实现功能}
};
window* create_window()
{
    window* wind = NULL;

    if(system_str == "win32")
         wind = new win_window();
    else if(system_str == "linux")
         wind = new linux_window();
    else if(system_str == "android")
         wind = new android_window();
    else
         wind = NULL;

    return wind;
}