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<== Date ==> <== Thread ==>
Subject: order of DTYP and INP/OUT fields in db-Files and vdct
From: Thomas Birke <[email protected]>
To: [email protected]
Date: Fri, 09 Dec 2005 13:34:31 +0100
Hi,

we just found the "feature" again, that in record-sections of db-files, the DTYP field has to be set before the INP or OUT field (at least for INST_IO), it took us an hour or two to track this down.
I didn't search for that in the AppDevGuide and other docs, since I'm afraid (and definitely hope), I'll find that documented, since I found tha last reference to that "feature" on tech-talk back in '99. It was undocumented back then...

So for about 10 years, we didn't have a problem with that here at BESSY, but the following is, what just happened:

  1. A colleague created a db-file for his application with vdct
         * he set the INP field of his whatever-in-record properly, but
           forgot to set the DTYP at all
  2. He recognizes his mistake and opens his db-file in vdct again and
     sets DTYP as well


So far, everything looks good, BUT:

   * When vdct writes the db-file, it puts the fields in the order in
     that they were set!
     Fields added in another vdct-session or after another "Open" are
     appended to the list of already defined fields!
   * Hence, vdct creates a db-file, that won't work at all (INP is set
     before DTYP is) while looking absolutely correct (to the untrained
     eye).


My first suggestion would be to change dbLoadRecords() (dbPutString(), and/or setLinkType() in dbStaticLib.c) and remove the dependency, but I also see, that it's a lot easier to modify vdct in a way to always write the fields in the order they were defined in the dbd-file (or at least write DTYP before INP or OUT).
The latter would be a workaround, that would keep us safe for the next 10 years...

Regards,
Thomas

--
______________________________________________________________________
/homas.Birke @ bessy.de

BESSY                                           Tel: +49 30 6392 4934
Albert Einstein StraÃe 15                       Fax: +49 30 6392 4859
12489 Berlin
Germany


Replies:
Re: order of DTYP and INP/OUT fields in db-Files and vdct Marty Kraimer
Re: order of DTYP and INP/OUT fields in db-Files and vdct Michael Abbott
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