Re: 'withing' problem

["David Crocker" <dcrocker@imsltd.com>]

Thanks for that, I didn't realise that Gnat Pro was used for critical
applications. I will investigate it further.

Regards

David Crocker www.eschertech.com

"Robert Dewar" <dewar@gnat.com> wrote in message
news:5ee5b646.0111020649.4c0f973f@posting.google.com...
> "David Crocker" <dcrocker@imsltd.com> wrote in message
news:<3be27344$0$227$ed9e5944@reading.news.pipex.net>...
> > Are there any commercial compilers with language
> > extensions to work around the infamous "withing" problem?
>
> Yes, GNAT Pro implements a version of the "with type" proposal that
> was made some time ago to solve this problem.
>
> > I am also aware that GNAT implements a workaround
>
> This is not a "work around" but rather a language extension
> feature that directly addresses the problem.
>
> > but what we really need is a validated compiler
>
> The presence of extensions in a compiler does not mean the
> compiler cannot be validated, providing that there is a way
> to turn off the extensions, as is the case with GNAT Pro.
>
> > I heard that the next update to the Ada language circa
> > 2005 will address the problem, but this is too far away
> > to be any consolation. Surely we can't be
> > the only company that needs the problem fixed urgently?
>
> The only way to have an "urgent" fix to this problem is
> to go with implementation extensions of the kind in GNAT
> Pro. Yes, they won't be fully portable to other compilers,
> but there is no immediate urgent short term solution that
> will solve that. Note that the ARG is still discussing the
> preferred long-term solution, and has recently been examining entirely
> different approaches. The sequence of
> events is that first the ARG approves a detailed proposal,
> the WG2.1 approves it, then it appears in an official
> addendum. Even the first step is a way off, and so I do not
> expect vendors to be implementing a common solution anytime
> soon, and indeed, even if the ARG does approve a solution,
> that is no guarantee that any vendor will implement it on
> any particular time schedule.
>
> > How do developers of large military software systems
> > manage?
>
> Well at least for our customers, they use the feature we
> have provided in GNAT Pro. This feature was not implemented
> for our amusement, but rather in response to serious customer needs.
>
> Robert Dewar
> Ada Core Technologies