Re: Teaching new tricks to an old dog (C++ -->Ada)

["Jerry Coffin" <jcoffin@taeus.com>]

Dr. Adrian Wrigley wrote:

[ ... ]

> I was particularly focusing on large software projects.  These always
> have high levels of resources - perhaps $100m+.  Something like
> a Social Security administration system, or an Air Traffic Control
> system.  The stakeholders really can't afford to have projects
> collapsing at the rate of 50%-70%.

Precisely -- you were originally discussing large projects, but nothing
in what you quoted from Google says it was doing the same. It's
_possible_ they were talking strictly about large, well-funded,
well-managed, (etc.) projects -- but nothing I saw in what you quoted
said or even suggested any such thing.

[ ... ]

> You are saying that the large software projects have a significantly
> lower failure rate?  And this is obvious to those with business
> acumen?  And obvious that the large project's success is independent
> of the language choice?

I'm saying that those that are well funded and carefully managed have
lower failure rates, and yes, I'm reasonably certain this is fairly
obvious. I did not say that the project's success was independent of
the language choice -- I said that in these specific cases, the
language choice was exceptionally unlikely to affect the the outcome.

Language choice is a factor, but is far from the ONLY factor, and in
the overall scheme of things is a relatively minor factor.

> I have not come across any studies that support these "obvious"
> findings.

It seems unlikely to me that you'd find any number of studies, no
matter how explicit the findings, to be convincing.  Just for an
obvious example, Ada advocates like to point out how Boeing chose Ada
for the control systems in the 777. By contrast, Airbus is currently
using the SCADE toolset which is a C IDE (though in fairness, the
programmers do little work directly in C).

Boeing has an extremely large market share, but has recently been
relatively stagnant, and recently seems to have retreated from pushing
the envelope and moving toward relatively small projects (e.g. the
7E7).  Airbus is growing (mostly at Boeing's expense) and working on
some of the largest projects of their type ever contemplated (e.g. the
A380). Looking at safety statistics on the Boeing web site at:
http://www.boeing.com/news/techissues/pdf/statsum.pdf
doesn't seem to show any major problems with reliability or safety in
the Airbus designs (and it hardly seems likely that Boeing would cover
up their competitor's shortcomings).

I'm the last to attribute these facts directly to C vs. Ada, but it
doesn't seem to indicate that using Ada is particularly crucial to
either economic or technical success in this market, which places about
as high an emphasis on reliability as any. I'd also note that SCADE is
routinely used in other high-reliability markets as well, including
other transportation and nuclear plant control.

> Curiously, if the C++ community says language choice is irrelevant
> to project success, but the Ada community says it matters, perhaps
> managers should always hedge their bets by choosing Ada(?)

First of all, I've seen nobody claim that language choice is
irrelevant. Second, I think a claim that choosing language X will
greatly improve chances of success (at least where X is replaced by
either C++ or Ada) says a great deal about the level of zeal vs. sense
in the speaker, and very little about the languages themselves.

In fairness, I should add that in _some_ cases, language choice really
can make a huge difference -- usually when one language is oriented
quite specifically toward the problem at hand. Obvious cases would be
things like databases or symbolic math, where a language aimed
specifically at the problem domain may reduce development time by
orders of magnitude.

> "In one of the few times a manager has performed the same project
> several times using similarly experienced teams but with different
> programming tools, the use of Ada significantly boosted project
> success rates. At SUNY Plattsburgh, Professor John McCormick has
> assigned the same real-time programming project to his class for nine
> years."
>
> "Working in teams of three or four, McCormick's students must write
> 15,000 lines of code to control a system that would need about 150
> switches to operate using hardware alone. In the five years students
> used C, no team completed the project -- even when more than half of
> the code was provided. With Ada, however, half of the teams completed
> the project before any support code had even been written. With some
> support code now provided, three out of four teams finish the
project."

The next time I have a tiny project to be developed by a small team
with no experience, I'll keep this in mind. :-)

> In summary:
> It simply isn't good enough for a language community to claim
> language choice is irrelevant, without giving real-world evidence.
> And why would such a claim attract us to the community?

TTBOMK, nobody has said it's irrelevant -- I've said it's only one of
many factors, and rarely the ultimate determining factor. I, at least,
am attracted to people who make claims that appear to be honest and
reasonable, and mostly repeled by those whose claims seem based more
religious zeal than honesty, intelligence or simply good sense.

[ ... ]

> How come "more expressive" templates, "better exception handling",
> or "less verbose" syntax is not claimed to improve project success?

Other factors _dominate_, but do not _exclude_ language factors.

I don't mean it as an attack on you, but you really do seem _extremely_
prone to treating things as absolutes, and IME absolutes are really
quite rare.

--
    Later,
    Jerry.

The universe is a figment of its own imagination.