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DInput callback problem

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I am writing an input class for DirectInput. I know that when you put the callback fucntion within this class it has to be static. But when I do this and call another member function out of my class which is not static I get this complie error: error C2352: Illegal call of non-static member function. How can I solve this problem without making this function static too or using a global function? Any ideas? I hope you all can help me, cause I want to finish this class tonight... ;-) The Wild Wild West - Desperado!

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Use the void "context" pointer to the callback to pass the "this" pointer for the particular instance of the class.

void CBlah::start() // <-- a non-static member
pDI->Blah( blah,..., CBlah::theCallback, (void *)this );

static HRESULT CBlah::theCallback( blah,..., LPVOID context )
CBlah *pthis = (CBlah *)context;

// access a member variable
pthis->m_aMemberVariable = 12345;

// call a non-static member function
return pthis->aNonStaticMemberFunction( blah )

Personally I tend to keep the code in the static callback really lean and do all the actual handling work in a non-static "OnCallback" function so that I don''t need to prepend "pthis->" to everything.

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You can use the method described above by S1CA. When registering the callback, DirectInput allows you to pass a pointer everytime the callback function is called. It is convenient to pass a pointer to the class that way the static callback function can call non static functions.

Another method is to have a global pointer to your class and initialize it in your constructor (using S1CA''s class names):

// Global pointer defined at the top of the CBlah.h file
class CBlah; // Prototype
extern CBlah* g_pCBlah; // extern global pointer

// Then in the CBlah.cpp file
CBlah* g_pCBlah = NULL;

// Finally in the constructor and destructor
CBlah::CBlah() : g_pCBlah(this) { }

g_pCBlah = NULL;

Now in the static function you can do the following:

static HRESULF CBlah::theCallback(...)
assert (g_pCBlah);
return S_OK;

S1CA''s method is cleaner...

Good luck!

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