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Samuel Mize <[log in to unmask]>
Reply To:
Samuel Mize <[log in to unmask]>
Tue, 8 Jun 1999 12:13:24 -0500
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Robert I. Eachus wrote:
> At 05:55 PM 6/7/1999 -0400, Victor Giddings wrote:
> >At 11:18 AM 6/7/99 -0400, Terry J. Westley wrote:
> >>It has been recently suggested that, rather than converting
> >>to Ada 95 (well, really, it's converting from VADS to GNAT
> >>or Rational Apex), we spend the same money to investigate
> >>converting to C++.
> >Our experience (and that of several customers) is that the effort to
> >transition for Ada83 to Ada95 is less than effort to port from one C++
> >compiler family to another.
>     I'll second Vic on this.  My experience with converting from VADS to
> GNAT has been that the ONLY noticible cost is the restesting.  Even on
> fairly large software suites, the time to get recompiled and up and running
> is less than it takes to talk about it.

This depends on how your code is written, but the cost should be
pretty trivial.  And, if you're moving to GNAT with support, you
should get some excellent support for the move.  ACT has worked
with several companies making exactly that switch.

(I happen to have no personal knowledge about Rational in this area,
good or bad.)

Here's the kind of item we found, just so you can see how far down
in the noise your conversion effort will be.  If I recall correctly,
when you give a size clause for a record, and it won't fit unpacked,
but it WILL fit packed, VADS assumes you want it packed.  GNAT makes
you explicitly pack it.  So, code that is written for VADS Ada may
require some added pragmas to work under GNAT.

This is a trivial change to implement, and the compiler will tell
you where it's needed.  I suspect that you won't be able to say that
about moving from VADS to *any* C++ compiler.  :=)

Sam Mize

Samuel Mize -- [log in to unmask] (home email) -- Team Ada
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