Re: Externalize DB/IO (was What Counts as Technically Slick?)

["Nathan M. Andelin" <nathanma@xxxxxxxxx>]

>From: "York, Albert" <albert.york@nissan-usa.com>

>I still think you are simply duplicating services
>that the operating system provides.

>I can't see how you have really separated the
>DB function from your program. All you've done is replace

>          READ  MYFILE

>with something like this:

>         CALL MYFILEIO
>         PARM   RecordBuffer
>         PARM  'READ' IOOption
>         PARM   IOResult

You express the same concerns I had.  And I wouldn't expect anyone to buy
off on this without trying it.  But maybe an example will help:

http://209.150.202.196/glcamp/rd1200p.htm

That's the entire code for controlling the User Interface for a database
inquiry and maintenance program.  You might notice it's missing a lot of I/O
related error checking, data validation, etc.  No *PSSR subroutine, for
example.  It's significantly smaller than a normal program that combines
logic for both screen I/O and database I/O.  Nearly all it's logic is
directly related to controlling the user interface.

Lets consider one code fragment:

If Not dbDelete(b_waid)
 Eval wsuMsg = dbMsg
 LeaveSr
EndIf

If dbDelete() were to delete a parent record, it might also delete all the
children under it.  But that's the sort of logic the UI control module
doesn't need to worry about.  Also consider how dbAdd() handles all data
validation without the UI control module worrying about it.  Also consider
how dbDelete() might return any number of error messages to the dbMsg
variable (I.E. Record not found..., Unable to get lock..., Unable to delete
child record...,  Not authorized..., etc.).  Again, that's DB/IO related,
and the UI controller doesn't need to worry about it.

Nathan.



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