cast class references to void and back

[BLS]

BLS schrieb:
> 
>  From the D spec;
> 
> Pointer Conversions
> Casting pointers to non-pointers and vice versa is allowed in D, 
> however, do not do this for any pointers that point to data allocated by 
> the garbage collector.
> 
> Given :
> Class CWin : CMsg
> {
>   Cwin pWnd = null;  // create a refrence
> 
>  /* C++
>  pWnd = 
> reinterpret_cast<CWin*>((long)((LPCREATESTRUCT)lParam)->lpCreateParams);
>   */
> 
>   // D probabely
>   pWnd = cast(CWin)(cast(LPCREATESTRUCT)lParam).lpCreateParams;
> 
> }
> 
> The LPCREATESTRUCT from WinUser.d
> struct CREATESTRUCTA {
>     LPVOID    lpCreateParams;   // Here I am
>     HINSTANCE hInstance;
>     HMENU     hMenu;
>     HWND      hwndParent;
>     // etc.
> }
> alias CREATESTRUCTA* LPCREATESTRUCTA;
> 
> So :
> 1) Do I have to put a cast(int) in there (where the (long) was in C++)
> The reason you would use 'int' and not 'long' is that long in C++ is 
> typically 32 bits and long in D is 64 bits.
> 
> 2) I'm not 100% certain that it is guaranteed to work if you cast class 
> references to void and back again.  Someone else might be able to 
> confirm/deny this.
> 3) Following the D spec. this is also not guaranteed to work. 
> confirm/deny ?
> 
> Thanks in advance
> Bjoern

Still someone out there who is still mental health ? 'cause const 
discussion :-)

In this case just  another question,
In case that I define
Class CWnd
{
   CWnd* pWnd = 0;

}
Do I have then in fact CWin** (from a C++ view) ?