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Is there a way to forward-declare the HINSTANCE type from the WinAPI without including the full (and big) windows.h header?
For example, if I have a class RenderWindow which owns an HINSTANCE mInstance, i will have to include windows.h in RenderWindow.h. So everything that needs RenderWindow also has to include windows.h.
I tried including windef.h but this seems to need some things from windows.h. :-( If I can't forward declare it, is there at least a portable way to use something like long mInstance in RenderWindow instead of HINSTANCE?
763
Because it wouldn't make sense to be able to declare something in the global namespace if you're inside a namespace {} block. The reason friend class BF; works is that it acts like an implicit forward declaration.
But you can't forward declare a typedef. Instead you have to redeclare the whole thing like so: typedef GenericValue<UTF8<char>, MemoryPoolAllocator<CrtAllocator> > Value; Ah, but I don't have any of those classes declared either.
In computer programming, a forward declaration is a declaration of an identifier (denoting an entity such as a type, a variable, a constant, or a function) for which the programmer has not yet given a complete definition.
HINSTANCE is declared in WinDef.h as typedef HINSTANCE__* HINSTANCE;
You may write in your headers:
#ifndef _WINDEF_
class HINSTANCE__; // Forward or never
typedef HINSTANCE__* HINSTANCE;
#endif
You will get compilation errors referencing a HINSTANCE when WinDef.h is not included.
75
You could declare it void* and cast the errors away. This is close to a never-ending battle though, sooner or later you'll get tripped up. Use pre-compiled headers so you don't care about the size of windows.h
stdafx.h:
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
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