Question

How can I ‘hide’ parts of a class so that whoever is using the libary does not have to include headers for all the types used in my class. Ie take the MainWindow class below, ho can I have it so when compiled in a static/dynamic libary, whoever is useing the libary does NOT have to include windows.h, ie HWND, CRITICAL_SECTION, LRESULT, etc do not have to be defined.

I know I could split it into two classes, an abstract class with just the public interface, and an implementation class which is hidden that contains the members that require windows.h.

The problem here is that the visible class can no longer be created itsself, and an additional create function (eg CreateMainWindow) is required. That is fine in this case since it is most likly that just a single instance created on the heap is wanted but for other classes this is not.

class MainWindow {     HWND hwnd;     int width, height;     std::string caption;     bool started,exited;     bool closeRequest;      unsigned loopThread;     CRITICAL_SECTION inputLock;      Input *input; public:     static void init_type();     Py::Object getattr(const char *name);      MainWindow(int width, int height, std::string caption);     ~MainWindow();      bool CloseRequest(const Py::Tuple &args);     bool CloseRequestReset(const Py::Tuple &args);      HWND GetHwnd();      int GetWidth();     int GetHeight();      Input* GetInput(); protected:     unsigned static __stdcall loopThreadWrap(void *arg);     unsigned LoopThreadMain();      LRESULT WndProc(UINT msg, WPARAM wParam, LPARAM lParam);     LRESULT static CALLBACK WndProcWrapper(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam); }; 

Answer 1

You can hide parts of a class using the so-called ‘cheshire cat’, ‘letter/envelope’, or ‘pimpl’ technique (which are, all, different names for the same technique):

class MainWindow { private:     //opaque data     class ImplementationDetails;     ImplementationDetails* m_data; public:     ... declare your public methods here ... } 

The best way is probably the abstract class mentioned in your 2nd paragraph (however I failed to understand your last sentence, in which you (tried/failed to) explain what your counter-argument to that is).