Hi All,

I am doing some Forth exercises with Petzolds examples.
( Programming Windows: Chapter 5 - Random Rectangles )
I struggled with the Dispather
\ ===============================================
 while (TRUE)

{
     if (PeekMessage (&msg, NULL, 0, 0, PM_REMOVE))
     {
          if (msg.message == WM_QUIT)
               break ;

          TranslateMessage (&msg) ;
          DispatchMessage (&msg) ;
     }
     else
          DrawRectangle (hwnd) ;
}
return msg.wParam ;
\ ==============================================

First I tried:

\ ==============================================
: Messageloop ( -- res )
        begin winmsg 0 0 0 PM_REMOVE PeekMessage
                if msg WM_QUIT <>
                        if winmsg TranslateMessage drop
                                winmsg DispatchMessage drop
                        then
                else DrawRectangle
                then
        again ;
\ ==============================================

Although the program works, the Forth system hangs after closing the
Window.
Then I tried a more literal translation:
\ ==============================================
: Messageloop ( -- res )
        true
        begin
        while winmsg 0 0 0 PM_REMOVE PeekMessage
                if msg WM_QUIT =
                        if false
                        else winmsg TranslateMessage drop
                                winmsg DispatchMessage drop
                                true
                        then
                else DrawRectangle
                        true
                then
        repeat winmsg 2 cells + @ ( wparam) ;
\ ==============================================

This version works fine, but now I am confused.
It seems to me that the Messageloop will only run the part between
WHILE and REPEAT until it recieves the WM_QUIT.
Obviously the two missing lines should be coded:
the first: TRUE
and the last after the REPEAT: winmsg 2 cells + @
I don't see how the last line is reached, and what sense makes the first?

Cees

.
Received on Sun May 21 2000 - 11:02:08 PDT