Access object field in a CALLBACK function (WINAPI - C++) - c++

Question

I'm using the SetWinEventHook() function like in the example by MSDN: https://msdn.microsoft.com/en-us/library/windows/desktop/dd373640(v=vs.85).aspx.
Like in the example above, to handle events I use the CALLBACK functionHandleWinEvent().I'm pretty new in using this type of function: what I've understood is that this function is called
asynchronously and parameters are passed automatically. Now I want to access to the list inside the function. I declared this function inside my class:
Class Example
{
private: std::list <int> events;
void CALLBACK HandleWinEvent(HWINEVENTHOOK hook, DWORD event, HWND hwnd,
LONG idObject, LONG idChild,
DWORD dwEventThread, DWORD dwmsEventTime)
{
events.add((int)event);
};
void Initialize_Hook()
{
cout << "Initialization Thread messages..........." << endl;
CoInitialize(NULL);
g_hook = SetWinEventHook(
EVENT_SYSTEM_FOREGROUND, EVENT_OBJECT_FOCUS, // Range of events (4 to 5).
NULL, // Handle to DLL.
HandleWinEvent, // The callback.
0, 0, // Process and thread IDs of interest (0 = all)
WINEVENT_OUTOFCONTEXT | WINEVENT_SKIPOWNPROCESS); // Flags.
}
}
and I simply want to add the event's identifier to my list, but it doesn't recognize events. There's a way to make the function know what the list is?More specifically, I declared the CALLBACK function in the .cpp file, but I have to declare it as void CALLBACK HandleWinEvent(...) instead of void CALLBACK Example::HandleWinEvent(...) as I always do because the second choice gives an error in SetWinEventHook().

Answer 1

Following the hint provided by #David Heffernan, I decided to declare the list as static. Then I wrote a static method to get the list.In this way, inside the CALLBACK function I could get the reference to the list:
private: static std::list <int> events;
std::list <int>& getList() {
return *events;
}
// the callback is now declared in Example.cpp file
void CALLBACK HandleWinEvent(HWINEVENTHOOK hook, DWORD event, HWND hwnd,
LONG idObject, LONG idChild,
DWORD dwEventThread, DWORD dwmsEventTime)
{
Example::getList().add((int)event);
};
(I didn't try with int, with a list of Example2 class worked).