Callback Function in Windows

The callback function must be defined as a global function or a static class member function.

This parameter is not provided for callback because the member function of a common class calls the implicit passed this pointer.

For example:

Enumerate the APIs of windows in the current system.

Bool enumwindows (wndenumproc lpenumfunc, lparam)

The callback function is:
Bool callback enumwindowsproc (hwnd, lparam );

If you want to set the callback function as a member function of the class, you must declare the following in the class:
Static bool callback myenumwindowsproc (hwnd, lparam );

Implementation:
Bool ceasygamedlg: myenumwindowsproc (hwnd, lparam ){
 // Do...
 Return true;
}

In this case, the this value cannot be used in the myenumwindowsproc implementation.

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It can be noted that in enumwindows, an lparam is provided for us to pass our own
Parameter, so we can pass this pointer in:

Enumwindows (myenumwindowsproc, (lparam) This );

--------------

Bool ceasygamedlg: myenumwindowsproc (hwnd, lparam ){

 Ceasygamedlg * _ this = (ceasygamedlg *) lparam;

 _ This-> MessageBox (title );

 Return true;
 
}