Re: Do we need "Mission-Critical" software? Was: What to Do?

[mark_lundquist@my-deja.com]

In article <93mqvp$qjp$1@trog.dera.gov.uk>,
  "Kevin Rigotti" <rigotti@atc.dera.gov.uk> wrote:
> mark_lundquist@my-deja.com wrote in message <93l410$mt6
$1@nnrp1.deja.com>...
>
> >You haven't substantiated your claim that programming GUIs in C/C++
> >is "cheapest and easiest".  You're just saying, "Who cares, it's only
> >the GUI -- just so long as I get to write my clever stuff in Ada",
> >right?
> Careful. That's not what I said.

Sorry!  Maybe I read in too much...

>
> If it so happens that the cheapest and easiest solution is C/C++ then
it
> makes sense to use it,

Yes.  If it so happens.  One difficult thing about Ada advocacy is that
people often think Ada is expensiver/harder when it would actually be
cheaper/easier, but I don't deny that there _are_ situations in which
C/C++ is the cheaper/easier.  Another bummer is the tendency to look
ahead only as far as getting the software to alpha release level and
not considering the rest of the lifecycle...

> particularly when the "product" is the results of
> using the software not the software itself.

Right... that's to the "lifecycle" point.  In this scenario the
software is a one-off, so the values of understandability, resilience
to change etc. that dominate in long-lifecycle projects don't become
significant here.  Significant value from Ada can still be realized in
these projects, but it happens longer-term across many (one-off)
projects -- because then you're amortizing the learning curve of
adopting a new language.  It'd likely not pay off on the first such
project.

>
> >Here again, I suspect that by the word "trivial" you mean
> >that they are uninteresting to you personally...
>
> No, I mean trivial. In the cases I'm talking about they genuinely are.
>
> >Hence I would expect that I would probably say the class of
> >cases where Ada is less suitable is probably smaller than you would
> >probably say it is. :-)
>
> Probably not, actually.
> I'm struggling to think of things where I would consider that the Ada
> *language* was less suitable, it is more a question of cost and
availability
> of skills.
>
> I've just finished writing 50k lines of air-miss model that I *chose*
to
> write in Ada ... I'd hardly have done that if I didn't like it :-)
>
> >On a side note -- I originally implemented this licensing component
in
> >C++, but the integration issues due to platform differences and
> >compiler version dependencies in a multiplatform, shared-library
> >environment made this impossible, as far as I could determine.  So I
> >had to reimplement it in C, ripping out all the STL and hand-coding
the
> >collection stuff, etc.
>
> Exactly. That's half the point I was trying to make.

Just to make C++ talk to C++, I had to make a C wrapper around the C++
class, then make a client-side C++ wrapper that called the C interface,
to make it into a class again.  Sheeesh...

> C++ is a real pain in the neck ... but it's not going to go away so
we need
> to work with it.

Agreed!

>
> >Aren't you letting the tail wag the dog?  You're saying that the
> >ability to integrate "seamlessly" from Ada to C/C++ is crucially
> >important, otherwise you might be forced to implement your "clever
> >stuff" in C/C++ just so you can avoid the cost of cross-language
> >interfacing to integrate with the "trivial" part, which somehow can
> >only be implemented in C/C++.  If it's so trivial, why would it be so
> >unreasonable to implement it in Ada, especially if you already have a
> >binding that hides the cross-language level of integration from you
to
> >begin with?
>
> Yes, I know it sounds daft but it happens.
>
> Remember, the original thread was talking about how to improve the
uptake of
> Ada and anything that might make it easier to convince sceptics that
Ada is
> easy to mix and match would help with this.

Sorry, I lost track of the original thread :-) but in that context I
agree with the point you are making.  I was mostly responding to the
opening comments in your post (which maybe I took out of context).

>
> >You seriously have part of your product that is so unimportant that
it
> >can be fully entrusted to young cheap C++ hacking?  I find that hard
to
> >believe...
> Software's not the product I produce: the simulation results are.
>
> >C++ hacking leaves no time for learning what real software
engineering
> >is all about :-)  All time is consumed with chasing down link-time
> >errors and debugging run-time errors.  Meanwhile it conditions
> >programmers to think that nonsense is normal...
> :-)
>
> That's when you need an Ada programmer to walk past with a smug
grin :-)

With your sick and twisted perspective, I'll bet you do that well...
:-) :-) :-)

Best Regards,
Mark Lundquist


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