Ada95 Should be a Multivolume ISO Standard. -- was Two ideas for

Ada95 Should be a Multivolume ISO Standard. -- was Two ideas for

[Robert C. Leif, Ph.D.]

From: Bob Leif, Ph.D.
Ada_Med

To: John_Volan et al.
You Wrote
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"More broadly, I'm also glad to see that there's some thought about
allowing Ada95 to evolve even before ISO gets around to the next major
revision. Nobody's perfect, and nobody's perfectly clairvoyant either,
including the people who write language standards.  But the ability to
correct mistakes and adapt to new circumstances is a sign of good
health.  For this reason, I believe it's vital that there be some
mechanism for discussing, experimenting, implementing, and sanctioning
revisions and extensions to Ada95.  But I disagree that this mechanism
should be "informal" or "semi-recognized."  There should be some
formally-accepted way to perform corrective and adaptive maintenance on
the Ada95 standard.  Is there one? If there isn't, could somebody with
some clout step in to fill the vacuum, perhaps a coalition between ACT
and Intermetrics? Is this already the de facto situation?"
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The first step is to change Ada 95 from a single to a multivolume ISO
standard. The specification of Ada presently is based on the waterfall model
and occurs at periods greater than a decade. A multivolume standard would
permit the classic software approach of divide and conquer. The spiral mode,
which is the method of choice for most software development, should be
applied to Ada.

The second step is to employ some standard's group, such as the IEEE, to
place its imprimatur on Provisional changes to Ada. I define  Provisional
to mean, this is our present design; but, we can  NOT guarantee that it will
stay in its present form. Experience may require that it be changed.

My personal choice for the standard's group is ACM SigAda. I quite well
realize that the ACM is presently not a standards organization. However, the
ACM SigAda has the great advantage of being composed of Ada enthusiasts.

Yours,
Bob Leif

Re: Ada95 Should be a Multivolume ISO Standard. -- was Two ideas for the next Ada Standard

[Robert Dewar]

Bob Leif suggests

"My personal choice for the standard's group is ACM SigAda. I quite well
realize that the ACM is presently not a standards organization. However, the
ACM SigAda has the great advantage of being composed of Ada enthusiasts."

I strongly disagree with Bob Leif's suggestion. Yes, ACM SigAda is indeed
a great source of Ada enthusiasts. It is thus a good source of ideas for
language changes, and indeed during the Ada 95 process, many of the
suggestions for change originated from the language issues working group
of SigAda.

However, it is not a suitable group at all for generating formal changes
to the standard, since this is an activity that requires more than
enthusiasm. It requires a substantial expenditure of time (not something
SigAda volunteers are likely to be able to provide), and a lot of
experience in language design, and a VERY detailed knowledge of the
semantic issues in Ada.

The whole idea of a multi-volume standard for Ada is a bad one. it is
a recipe for changes getting into the language without adequate study
and care.

Much better is to keep the entire process of developing extensions to
Ada informal, as has been done very successfully with other languages
(note that C++ is not yet even a single volume ISO standard!)

Let's discuss ideas for changes, a good example is Tuck's with type
suggestion for solving the circular reference problem, agree on possible
approaches, and then prototype and experiment with these ideas using GNAT
(that's one of the things GNAT is intended to enable!)

Then if an idea seems like it is reasonable and has consensus, it can
be developed as an informally agreed on extension by the various vendors,
which will allow us to investigate possible implementation problems.

If there are no such problems, then eventually the feature may find its
way into the next version of the language, or it may still not, because
the whole point of a language revision is to study the coherence of 
various possible features. if all the good ideas for Ada 9X had been
added to Ada 83 one by one, we would have a horrendous mess on our hands.