Re: Confusing language, was Re: Help help.. please.i am totaly new in ada programing

[Marin Condic <condicma@bogon.pwfl.com>]

Robert Dewar wrote:

> Note as a contrast Ada's view of how to store dates, which is
> completely hidden from the programmer. If you instantiate
> sequential I/O for a type with Calendar.Time in it, you get
> a tape full of highly implementation dependent data, something
> that one avoids like the plague in the COBOL world.

The COBOL model is superior in many ways to the Ada model in this area.
Wherever you have a significant database or important files of some
sort, you generally have no idea who or how will be using that data
across its useful life. When I was working for the City of Chicago, we
had traffic accident data on tape going back 15 years - still in the
original flat-file format. There had been dozens of technological
changes since the first data was recorded. Many systems were built using
a variety of tools which used the data as input. Had there not been some
kind of common representation (character, in this case) for dates and
numbers, etc., the problems associated with working with the data could
have been immense.

When I was developing some applications here at Pratt that would be
storing important data with a long life, I built myself a package of
date tools that would take objects of Ada.Calendar.Time and convert them
to a variety of useful string formats. Since I figured I'd likely be
around at Pratt when Y2K hit (as it turns out, not) I didn't want to be
stuck fixing the problem, so externally, I stored all data as: YYYYMMDD.
The conversions coming in or going out were pretty trivial and its
worked fine - my systems being one of the few to pass the Y2K audit
without modification.

Now if there were some sort of Industry Standard for storing dates/times
externally, it might be valuable to extend Ada.Calendar with some
conversions to do this. After all, most external character storage of
numeric values kind of have an Industry Standard (or at least lowest
common denominator) and Ada.Text_IO is capable of dealing with that
quite well.

MDC
--
Marin David Condic
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