Re: Ada to C Translator

[Marin David Condic <mcondic.nospam@acm.org>]

Speaking as someone who has worked on projects with a similarly long or
longer lifecycle, I'll throw this in: Nobody has a crystal ball with enough
magnifying power to see that far ahead. Example: The F119 engine for the
Advanced Tactical Fighter was in various stages of development for over ten
years before it went into production. In that ten years, the engine control
went from running 68000 processors to 68040 processors (with stops in
between). Before it got to production, Motorola decided that they weren't
going to make a Mil packaged version of the chip anymore no matter how much
whining and snivveling we did. The box will ultimately go into production
using PowerPC chips. The project had frozen a version of the XD-Ada compiler
for a long time and kept VAX/VMS systems around to run it on in spite of
everyone else at the company going to Sun/Unix platforms. Eventually the
project was forced to move on to the Aonix Ada95 compiler for the PowerPC
chip. All that meant major rewriting of the system level software and
reverification of the control. No small task.

Since projects like this can't possibly forsee what will happen 20 years
from now (new charged particle phased plasma fluidic computational devices?
or maybe total economic colapse followed by a meteor impact that throws us
all back to the stone age?) the powers that be on the project have to have a
plan to deal with the inevitable changes. If you were to, for example, pick
Ada as your programming language and Linux as your OS, what you would want
to do is design the software to isolate machine/OS specific features so they
could easily be replaced and develop your software so that it is clear,
easily understood and readily translated if that need should arise. Ada
shines in these areas for lots of reasons such as readily understood syntax,
modular construction, etc. Ada was designed specifically to support large
projects with a long lifespan. If you write it in Ada, at least your
grandson can come along 20..30 years from now and maybe understand what you
did and translate it into C** or F# or whatever is the new, hip computer
language  at that time. (Personally, I'm predicting a resurgence in the use
of Jovial. :-)

What was it they said in The Mythical Man-Month? When you develop software,
plan to write it twice because you will anyway.

MDC

Dave Ptacek wrote:

> I would be interested in some suggestions as to what languages and
> toolsets would be viable alternatives for maintaining a program 15 - 20
> years into the future.  Please try to take the Ada hat off before you
> respond, it still might be your choice, attempt to rationalize it with
> reasonable statements, consider the logistical situation noted above and
> lastly this is not a "deep pocket" program so funds are limited.

--
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Marin David Condic - Quadrus Corporation - http://www.quadruscorp.com/
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