Re: Chain and Readc

[Booth Martin <booth@xxxxxxxxxxxx>]

This is a personal choice, I know.  It helped me a lot when I switched 
to this, so I pass it on for whatever it might be worth to you:

First, deprecate the READC solution.  That was useful way back when we 
had 300 baud modems, but today it is just one more place you can develop 
unexpected errors (like this one, right now.)

Second, use a for/endfor loop for the sfl chain.  Much cleaner code.

 c            for  sfl1rrn = 1 to sflsize
 c   sfl1rrn  chain sfl1
 c....
 c            endfor

Third, store the original data in the sfl record as hidden data so that 
you can check for changes right there, and you can refresh the subfile 
right from the sfl record itself, if the user requests it.  If you are 
updating data  files it is easy to tell if the original record has been 
changed in the meantime at another work station.  Plus, if the user 
changes the field and then changes it back to the original, you aren't 
making false changes.

Please accept this in the manner intended.  It saved me pots and pots of 
trouble, so I want to share it.  But it is most certainly a personal choice.

On 9/30/2010 4:27 PM, Paul Tuohy wrote:
> Hi Scott,
>
> Hate to disagree, but you should not need to display the subfile for the
> subsequent READC to work.
>
> The technique I have always used with "load all subfiles" is to perform
> a validation pass over a subfile (using a READC loop) and update each
> subfile record with SFLNXTCHG set. If any record is invalid, the subfile
> is re-displayed. Otherwise, another READC loop is performed - without
> any interim reference to the subfile control record.
>
> Only difference I see here is that a CHAIN is being used on the first
> read through the subfile.
>
> Regards
>
> Paul Tuohy
> ComCon
> www.comconadvisor.com
> www.systemideveloper.com
>
>
>
>
>
> Scott Klement wrote:
> > hi Florin,
> >
> > After marking the records changed (with the indicator for SFLNXTCHG) you
> > need to display the subfile before READC will see that the records are
> > changed.
> >
> > When I do something like this, I typically will use the WRITE opcode to
> > redisplay the SFLCTL record without waiting for user input.  That way, I
> > can go ahead and start reading them immediately.
> >
> >
> > On 9/30/2010 2:18 PM, Florin Todor - YYZ Concord wrote:
> >
> > > Hello,
> > >
> > >
> > >
> > > I have an issue, which, in my opinion shouldn't be an issue at all
> > > because it is pretty straight forward...
> > >
> > >
> > >
> > > Anyway, I have a subfile where I need to check (for ALL records) if a
> > > specific field has a certain value. I do this using CHAIN RRN op-code.
> > > I, also, want to make EVERY record available for the next READC
> > > operation; pretty simple, right? The only problem is it doesn't work!
> > > The READC does not see any "changed" record...
> > >
> > >
> > >
> > > Here is the relevant code:
> > >
> > >
> > >
> > > C     sr_chkhaz     begsr
> > >
> > >    /Free
> > >
> > >        s1rrn = 1;
> > >
> > >        Dow s1rrn<= 30   and
> > >
> > >          v_hazfrt = 'N';
> > >
> > >        Chain s1rrn R010D02;
> > >
> > >        If %found();
> > >
> > >          If #DHAZ = 'X' or
> > >
> > >             #DHAZ = 'H';
> > >
> > >            v_hazfrt = 'Y';
> > >
> > >          Endif;
> > >
> > >        *in37 = *on;
> > >
> > >        Update R010D02;
> > >
> > >        *in37 = *off;
> > >
> > >        Endif;
> > >
> > >        s1rrn += 1;
> > >
> > >      Enddo;
> > >
> > >      s1rrn = 1;
> > >
> > >      Write R010D03;
> > >
> > >    /End-free
> > >
> > > C                   endsr
> > >
> > >
> > >
> > > *in37 turns on/off SFLNXTCHG for R010D02 Subfile record:
> > >
> > >
> > >
> > > A          R R010D02                   SFL
> > >
> > > A    37
> > >
> > > AO 69                                  SFLNXTCHG
> > >
> > >
> > >
> > >
> > >
> > > The excerpt of the main program:
> > >
> > >
> > >
> > > ......................................................
> > >
> > >
> > >
> > > C                   exsr      sr_chkhaz
> > >
> > > C                   move      *off          *in35
> > >
> > > C     *in35      doweq     *off
> > >
> > > C                  readc     r010d02                                35
> > > <<<<<<----------*in35 is turned *on
> > >
> > > C     *in35      ifeq      *off
> > >
> > >
> > >
> > > ........................................................................
> > > .............
> > >
> > >
> > >
> > >
> > >
> > > Any thoughts?
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Thank you
> > >
> > >
> > >
> > >
> > >
> > > Florin Todor
> > >
> > >
> > >
> > > <mailto:ftodor@xxxxxxxxxxxxxxxx>