How do I force export from within a loop

[Mike Schwartz (PC Support)]

> -----Original Message-----
> From: filepro-list-bounces at lists.celestial.com [mailto:filepro-list-
> bounces at lists.celestial.com] On Behalf Of John Esak
> Sent: Wednesday, August 17, 2005 4:25 PM
> To: filePro mailing list
> Subject: FW: How do I force export from within a loop
> 
> 
> 
> -----Original Message-----
> From: Doug Campbell [mailto:doug.campbell at yestechtoday.com]
> Sent: Wednesday, August 17, 2005 2:56 PM
> To: john at valar.com
> Cc: mschw at athenet.net
> Subject: Re: How do I force export from within a loop
> 
> 
> >>John Esak wrote:
> 
> >>This is not correct. If Stuart has explained it that way in his book, no
> >>matter how many times he's reprinted it, he's still wrong. A WRITE will
> in
> >>no way export a line to an export file. Unless, the EXPORT line itself
> is
> >>within the loop (getnext or any other kind of loop which gets successive
> >>records) nothing will be added to the export file. So, unless you mean
> >>something else, or Stuart explained it some other way, this is just not
> >>correct.
> >>...
> >>
> >>
> >>
> >>
> > Hi John,
> > I'm going to have to side with Mike on this one. I don't know if my
> > reply to the
> > original question made it to the list (as often they are rejected), but
> > the code
> > snippet I included is almost verbatim from a working program. I only
> > execute
> > the EXPORT statement one time, and then I do all of my buffer output
> > through
> > repetitive use of the WRITE command. I certainly agree with you that
> > hitting
> > the EXPORT again in a loop should accomplish the same thing. It just
> seems
> > strange to me to keep re-defining the output stream. I'm a C coder by
> > nature,
> > and I relate EXPORT to fopen() and WRITE to fflush(). My code snippet
> > copied
> > at bottom, in case it missed the list.
> >
> > Regards,
> > Doug Campbell
> > Yes! Tech Today, Inc.
> 
> > :
> > : export ascii mybuf=/tmp/names.csv r=\n f=,
> > - - - - -
> > : 'output header row (if desired)
> > : mybuf(1)="First Name"; mybuf(2)="Last Name"; write mybuf
> > - - - - -
> > :
> > : lookup names k=1 i=a -nx
> > - - - - -
> > loop: not names
> > : goto done
> > - - - - -
> > : names 'output data row for each lookup record found
> > : mybuf(1)=names(1) ; mybuf(2)=names(2) ; write mybuf
> > - - - - -
> > :
> > : getnext names ; goto loop
> > - - - - -
> > done:
> > : ....
> 
> Hmmm, well, as soon as I saw that Mr. Tartaglia had gotten some success
> from
> using the WRITE in his getnext loop. I went and tried the procedure
> immediately. It did NOT work.  Okay, I wrote my note to the list. I knew
> it
> doesn't work that way. WRITE does a WRITE, ExpORT does an EXPORT. :-)
> 
> Then I get Doug's letter and wonder what is up. Turns out, we are both
> right. Well, the WRITE-EXPORT will NOT work in *clerk.... which, of
> course,
> is where I tried it out. (Murphy, of course.)  However, it does work in
> *report. So, I called Ken... Turns out he was checking things out also and
> had just discovered this. I told him that it did NOT work for me in clerk
> and he said that he remembered (like me) that EXPORT itself did not used
> to
> work in clerk... the early days. It was only an output function. Then,
> somewhere along the line (Dave Roeger, he thinks) probably *added* the
> code
> which allows WRITE to update an EXPORT at least when you're in report. Ken
> was also under the impression that WRITE would not refresh an EXPORT.
> Neither apparently did Ron Kracht, who he had just asked also.
> 
> So, there you have it, I (we all, actually) stand corrected. Using a WRITE
> in a getnext loop will send out the export again. However, it is still not
> and probably never will be a documented function of WRITE. And, it will
> probably never be changed to work that way in clerk also. Who knows. In
> any
> case, I think it is important to understand the very _different_ nature of
> the EXPORT command and the WRITE command. If you mix up the purpose of
> these
> two commands, there will be other times when you will not get the desired
> results.
> 
> So, I apologize for stating it according to the docs and the intended
> behavior of each command. I don't think would ever use it that way, but
> then
> again, if your understanding of things allows you to picture the workings
> in
> this way, no problem.
> 
> As for the C analogy. Okay, for all practical purposes the EXPORT could be
> an fopen(), however the WRITE is not like a flush() to me. Think of it
> this
> way. If you did not get another record and issued another WRITE, you would
> get another line written to the file. If you had just opened a file with
> lookup r=free and did more than one WRITE, by your logic here you might
> expect to see multiple free records written... which obviously won't
> happen.
> 
> So, to keep things straight, I like to think of needing to go through the
> EXPORT line to actually send the data out. The fact that WRITE was
> modified
> to do this (in report only) is a fluke and was probably added for a
> specific
> need one time, which is why it remains undocumented and probably never
> will
> be.
> 
> It may sound strange, but I do all of my importing and exporting from a
> stand file in clerk. Always have. It just gives me more flexibility when
> querying for which records to manipulate. I suppose I should have tried
> this
> in report before sending out my message... but, even when I found it to
> work, I still would not recommend it. Adding a new line to a file, or a
> new
> record to a filepro key is not the job of WRITE. As always, this is only
> IMHO. And after learning this today... the H does not mean Honest it means
> Humble!  Thanks Doug.
> 
> 
> --
> John Esak
> Visit The FP Room www.tinyurl.com/97y9u 24/7
> 
> Author of:
> The filePro Survivor Series
> Video training for filePro on CD
> Samples at: www.valar.com/training
> 
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     Well, if there is an apology in here someplace, I (and, by proxy,
Stuart) both accept for saying that flat out I am (we are) not correct.  I
was pretty sure that's how I have been writing exports for many years now.  

     I do thank you for testing that in *clerk, though.  I would have
expected it to work with WRITE in *clerk.  It makes perfect sense to me that
once I open an export and give it an alias handle, then I should be able to
do WRITEs to it, just like any other filePro file.  

     I don't ever recall doing that from *clerk, though.  I do all my
exporting from *report.

     (And I have enjoyed the couple of filePro Survivor clips that I have
listened to so far.  Even with my 20+ years of filePro work, I picked up a
couple of tips, but it was interesting seeing how you write code.) 

Thanks,

Mike Schwartz