Pointer to Object Questions

[Jarrett Billingsley]

"John Kiro" <johnkirollos at yahoo.com> wrote in message 
news:en6pvm$23fk$1 at digitaldaemon.com...
> Speaking about casting, there is usually a need to cast a reference to an
> integer & vice-versa; I'm specifically pointing to the case of using a 
> function
> like the Win32 API function SetWindowLong(), in order to link a window 
> with a
> corresponding object. Here is how I did it:
>
>  //Linking view window to view obj:
>  SetWindowLong(hwndView,0,cast(uint)(cast(CView*)this));
>
>  //retrieve the object given the window handle:
>  cast(CView)cast(CView*)GetWindowLong(hwndView,0);
>
> Casting to void* instead of CView* also compiled without errors.
>
> So is this the usual way of doing such thing? I mean double casting?
> Because casting an object to int or vice-versa is rejected by the 
> compiler.

Yes.  Though you should use the

cast(uint)cast(void*)this

form, as this is the more generally accepted way.  It makes it obvious that 
you're getting the pointer value of the reference, compared to

cast(uint)cast(CView*)this

Since 'this' is of type CView, casting CView to CView* doesn't really make 
sense, but casting to void* does -- it says "I want a raw pointer."