Re: Ada to C Translator

[Robert Dewar <robert_dewar@my-deja.com>]

In article <alpl29.aph.ln@leia>,
  Frode =?ISO-8859-1?Q?Tenneb=F8?= <frodet@nvg.org> wrote:

> I'm not sure what type of application you have, however 15
> years ago  there were a lot fewer languages than today.

That seems clearly false. What is your authority for this
statement/guess. Perhaps you mean that there are fewer
languages with which you are familiar (given the rest of
the message that seems a possibility).

> How many of those languages are alive today?

Virtually all of them. Nothing is more discouraging than seeing
supposedly knowledgable Ada folks decide with no evidence that
other languages have disappeared from sight. It is indeed a
common malady to assume that any language you do not bump into
every day has disappeared (for example, I often meet people who
think that PL/1 has disappeared). But surely Ada folks should
try to avoid this mistake, of all people!

> Can you get an actively maintained compiler for Cobol on a
> modern platform?

A staggeringly ignorant question :-) Yes, of COURSE you can,
and the amount of legacy COBOL out there is huge. Furthermore,
new applications are being generated in COBOL all the time
(that should not be surprising, COBOL is still the most
suitable language for fiscal applications -- yes, you can make
a reasonable technical argument for Ada-95, but most of the
people making language decisions assume that Ada has
disappeared -- see paragraph one above). As for active
maintenance, yes, there are certainly active COBOL compiler
maintenance groups around (e.g. for Computer Associates Realia
COBOL for IBM PC's, or don't these count as modern platforms in
your lexicon? :-)

> What about Forth?

Again, just because you do not bump into it every day, does not
mean it is dead, especially when you have made ZERO attempt to
find out facts. Of *course* Forth is alive and well, and is
used in many applications areas. There is by the way a VERY
nice Forth interpretor for the Palm Pilot, which has been used
to generate a number of Palm applications.

> The only laguage I can think of other than Ada and C which
> has a active compiler support is Fortran - even Pascal is
> struggeling.

Again, the lack of awareness in this statement is remarkably
parochial -- even peculiar, given its inclusion of Ada as one
of three languages still in use -- that would surprise a LOT of
people:-) There are hundreds of languages for which there is
active compiler support, and active application communities,
especially if you use Ada as a standard for what these terms
mean!

By far the most widely used language for PC development is
Visual Basic (although almost never taught in universities,
contrary to other claims you made). And for sure there will
be compiler support for this for a long long time.

> My point is that with Ada, you will most likely get a
> maintained compiler for a current platform in 15 years. Will
> this be true for C++?

Yes, of course it will. Ada advocacy is not helped by FUD like
this which is clearly unfounded. I agree that Ada compilers
will be maintained for 15 years, but that is because I know the
business strategy and plans of Ada Core Technologies. The fact
of the matter is that in terms of future maintenance of
compilers, C++ is in a VERY secure position (as is COBOL
incidentally :-)

> Also, you are switching to NT 4 NOW? NT has already reached
> EOL.

Again, that is unsupported FUD. I am the last person to write
strong words of support for NT, but to say that NT has reached
end of life is absurd.

> If  you had written any legacy application with C++ on
> Windows 3.11 five  years ago - how easy would it be to port
> it to any platform today?

It would vary on how well it was written, because you were
using a non-standardized language, still in flux, on an
obsolescent operating system, yes, you may have more troubles,
but the difficulty in porting programs is often more related to
quality of code than operating environment.

> How about in 10 years?

I don't think it would be any harder to do this port ten
years from now than now, probably easier, because more tools
will be around to help.

Of course I agree that porting Ada code to C++ just for the
sake of porting it seldom makes sense, but let's try to keep
the arguments real. Ada advocacy is not helped by extreme
statements about other languages that are insupportable.

> However, I would get your application running on an older
> version of GNAT for DOS

That seems a poor suggestion, this is a bad environment for the
port, and will make the job much harder (I speak from the point
of view of our experience in helping customers port millions of
lines of legacy code to GNAT).

> Depending on the cost structure of your system, a W2K license
> can be  significant compared to eg. Linux or BSD or even
> Solaris these days.

Indeed, and a Linux license is cheaper than a DOS license, so
the conclusion here should be that Linux is an obvious target.
It also supports development work much more reliably than any
of the Microsoft operating systems in our experience.

> I performed the major part of 'porting' a 200K SLOC (sic) of
> code from  SunAda 3 running on Solaris 2.5.1 to GNAT on
> Solaris 8 in less than 200
> hours.

One hour per thousand lines of code is actually rather slow
as a porting rate from our experience, especially for a fairly
small program (we have frequently helped with porting very
large applications in much less time than this on an absolute
basis, let alone a relative basis). But milage can vary, we
have at this stage a LOT of experience in such porting, which
can make things much more efficient, and as I said earlier,
difficulty in porting can reflect poor coding of the original
(the big issue being whether implementation dependent and
system dependent code is properly isolated).

Robert Dewar


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