Re: Depending on passing mechanism

[hbaker@netcom.com (Henry Baker)]

In article <mheaney-ya023680002110972333400001@news.ni.net>,
mheaney@ni.net (Matthew Heaney) wrote:

> I'm going to tell you a story, Henry.  It's called, What I Did At Work Today.
> Now, that was a real problem at my real job.  Do you feel that that was too
> difficult?  Dijkstra admonished us 20 years ago that we need to "minimize
> the intellectual distance" between a problem and the solution to that
> problem.  Doesn't this solution capture the qualities of the problem
> directly?

I agree that Ada's attempts to provide accurate ranges of numbers are
laudable.  But PL/I and Cobol offered equally (some would say more
equally) powerful capabilities.  But the history of Ada indicates a
deep disconnect between people like yourselves that have to deal with
real hardware and real data formats and the academics.  The academics
were worried about something totally different, and in fact, it first
appeared as though Ada would not be able to properly specify exact
hardware formats at all.  This is one case where 'real' programmers
were able to prevail.

The academic notion of number ranges was not wrong, but it was not
carried through.  Even a cursory glance at the 'interpretation' of
the Ada standard shows that they missed by a mile.

For example, there was no guarantee that a variable with a particular
range could be guaranteed to always have a value in that range!

There were no tools for Ada that would allow one to step through a
program and verify symbolically where range constraints were met, and
where they weren't met.  Such a tool would be invaluable in the verification
of a real-time embedded system.  Instead, Ada people spent all this time
on the semantics of exceptions, which people who actually had to program
reliable real-time embedded systems promptly turned off!