Re: Free Format and Screen Processing

On Fri, 13 Feb 2004, Bill wrote:

> I am trying to use Free Format as much as I can, but I've run across one
> type of program that is quite a pain:  Interactive screen processing.  I
> can't currently think of a slick way to bounce forward and backward among
> the screens without the use of Goto's and Tag's.  Since FF doesn't allow
> the Goto and Tag, I have to use the ugly /End-Free and /Free to jump in and
> out.
>
> Has anyone developed a slick way of moving forward and backward amongst
> screen displays without using Goto's?

This is less about free format and more about program design.  We try to
put each part of a program that corresponds to a screen in its own
subprocedure.  Typically we do something like the following psuedo-code:

  do ()
  exfmt SCREEN
  case 1:  eval  errno=do_process_1(parms)
  if (errno = EXIT)
  leave
  endif
  case 2:  eval  errno=do_process_2(parms)
  if (errno=CANCEL)
  iter
  endif
  enddo

This way you get modular code and avoid goto.

James Rich

"As for security, being lectured by Microsoft is like receiving wise words
on the subject of compassion from Stalin."
      -- mormop on lwn.net