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Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!COMMUNITY-CHEST.MITRE.ORG!munck
From: munck@COMMUNITY-CHEST.MITRE.ORG (Bob Munck)
Newsgroups: comp.lang.ada
Subject: Ada 9X/Y
Message-ID: <8910111843.AA11007@chance.mitre.org>
Date: 11 Oct 89 18:43:18 GMT
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Organization: The Internet
List-Id: <comp.lang.ada>


I hate to keep harping on this, but the emphasis of the Ada effort is (IMO)

       software engineering        NOT       programming languages
         life-cycle costs          NOT         development costs
    large, many-person projects    NOT        utilities and "toys"

The life-cycle of a large system is longer, perhaps much longer, than
the 10-year revision period of Ada.  I have a hope that the life-cycle
of large systems will become essentially infinite when coded in Ada;
that they will no longer "die" and be entirely replaced by a major
project, but rather "evolve" through many small improvement projects. 
("WIS: never again!")  Also, if we ever solve the managerial problems of
software reuse, the contents of repositories will essentially be systems
with very long life-cycles.

Use of a language, any language, that doesn't change is an obvious way
to save big money on long-lived systems.  (Compatible extensions are
less troublesome.)  It is important to note that "a language that
doesn't change" is not the same as freezing the current revision of the
compiler.  In some sense, code has to be "under continuous care" to stay
"alive."  That is, the world around a piece of code -- underlying OS,
hardware, I/O devices, data -- is continually changing.  A "frozen"
compiler will after awhile "fall into disrepair" with a long list of
known bugs and incompatibilities that will never be fixed.

It's a well-known but seldom-used fact that the cheapest way to have a
reliable, comfortable automobile over the long term is to maintain it in
tip-top shape; the most expensive way is to ignore it and buy a new one
when it falls apart.  I believe that this will prove true of software; a
system that's upgraded to the new OS, recompiled through the new
compiler revision, and moved to the new hardware will have the lowest
life-cycle costs.  Of course, auto and software maintenance can be
overdone and made unnecessarily costly.

Finally, the only change to Ada that I think is really necessary is my
own suggested extension of comments to include standard forms for
multiple fonts, graphic diagrams, images, and hypertext links to other
documents.
                 -- Bob <Munck@MITRE.ORG>, linus!munck.UUCP
                 -- MS Z676, MITRE Corporation, McLean, VA 22120
                 -- 703/883-6688