Re: MFC user-defined message vs. ptr to Wnd

"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp>
Thu, 23 Oct 2008 20:30:09 -0400
"Jimbo_Jimbob_Jiminator" <>
wrote in message

I have been getting my feet wet with the Windows programming thing (as you
have probably noticed from my recent posts!!). I usually do bare-bones
embedded programming.

Anyway, a couple of weeks back I posted about getting a pointer to the
parent of the parent (grandparent of the window?), so that I could have
property pages access a file that far back. I learned several ways to do
that. Also, what came out of that discussion was the fact that the best
would be to decouple the child (grandchild) and message back to the

I put a test case together and I was able to do that. I had to include the
header for the grandparent so that I could get a pointer to hWnd of that
class type. This hWnd has to go as part of the message.

This, then, brings up the architectural semantics of why is messaging is
much better. Yes, you don't really expose the inner data and structure of
grandparent class, this is a plus. However, the need to include the header
file of the grandparent into the child (grandchild?) and then be able to
a pointer to that object means that it is NOT as decoupled as I had hoped.

That's where you've gone astray. You do _not_ need to include the header of
a parent in order to send or post a message to it:


will do the job. Without needing the parent's header. GetParent returns a
CWnd*, which is good for any window. (A CWnd is MFC's encapsulation of the
HWND. Anything an HWND can do a CWnd can do.)

Scott McPhillips [VC++ MVP]

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