HP OpenVMS Systems

Mixing Screen Management? (COBOL, SMG)

» close window

The Question is:

 
While waiting for a response to my other question re: Compaq COBOL
ACCEPT/DISPLAY fiasco I have another along the same lines. Why does the new
DISPLAY not obey the VT200 save cursor and restore cursor escape sequence
commands?
 
If I issue DISPLAY "<ESC>7<ESC>[24;1HThis is a help line<ESC>8" then the
cursor is placed at line 24 column 20 and is not returned to the last
position it was called from. It seems to me that the DISPLAY should obey the
save/restore cursor escape sequence
s because it did obey the move to line 24 column 1.
 
...john
 
 

The Answer is :

 
  As discussed previously, when using extended DISPLAY/ACCEPT capabilities,
  the COBOL Run-Time Library (RTL) uses the Screen Management (SMG) RTL,
  and SMG takes total control of the display.  Escape and control sequences
  are explicitly and deliberately removed from the output stream to ensure
  that SMG knows precisely what the display looks like, and where the cursor
  is located at all times.
 
  The choice of the COBOL programmer is either to use the features of the
  COBOL ACCEPT/DISPLAY and accept that control of the display is entirely
  relinquished to COBOL, or to avoid use of the COBOL ACCEPT/DISPLAY
  extensions and manage the display directly via explicit escape and
  control sequences, or via explicit calls to the SMG, DECforms, FMS or
  other screen management package.
 

  

     

     
answer written or last revised on ( 17-NOV-1999 )
     
» close window