home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
High Voltage Shareware
/
high1.zip
/
high1
/
DIR9
/
A9X_0610.ZIP
/
9XNEWS.HLP
< prev
next >
Wrap
Text File
|
1993-05-11
|
7KB
|
145 lines
Form G30-0593
9XNEWS.HLP
Ada 9X Report to the Public
May 1993
The Schedule
I hope 1993 has been progressing well for you. This year, we begin canvassing
on Ada 9X for the American National Standards Institute (ANSI) and the
International Standardization Organization (ISO).
All Ada 9X Teams are working very hard to produce the draft Standard by August
1993 and to begin balloting by September. Many vendors are gearing up for Ada
9X, and I fully expect 9X beta-compilers to appear within the next 12 months.
ISO Approves Ada 9X Baseline
The ISO Working Group on Ada approved the entire Ada 9X baseline in November.
This followed last April's ISO approval of the language core minus the
Annexes.
With November's approval, essentially all of the baseline is defined and
attention is now focused on translating the base into precise Language
Reference Manual wording. While it is often the case with standards that not
everyone is happy, I am extremely pleased with the level of consensus we've
achieved and appreciate all the help given us by the ISO delegations, the ANSI
Technical Advisory Group, the ANSI Canvassees, and the Ada 9X Volunteer
Reviewers.
Upward Compatibility
I read an account of a recent conference panel in which the members stressed
the necessity for 100% upward compatibility between Ada 83 and Ada 9X. As is
often the case, certain rules and metrics seen to be applied to Ada that are
not applied to other languages. Achieving 100% upward compatibility is
virtually impossible in language revisions and has not been achieved in
recent/on-going revisions of COBOL, C/C++, or FORTRAN. It is inevitable that
by enhancing a language, certain incompatibilities are, by necessity,
introduced. The trick, of course is to minimize the impact of these on
mainstream programs.
A major design goal of Ada 9X has always been to minimize the need for
modifying the existing base of Ada 83 software to make it compatible with Ada
9X. This involves not only pursuing upward compatibility but also pursuing
implementation-dependent behaviors that are currently being relied upon.
In common with the experience of revising other language standards, it is
infeasible to guarantee 100% compatibility. For example, in COBOL 83 there
were some minor incompatibilities introduced which affect existing programs.
One example in COBOL is IS_ALPHABETIC, which now accepts upper- and lowercase
letters in the new standard. The transition from C to ANSI-C and from there
to C++ has not achieved 100% upward compatibility either. For example, C++
requires all procedure definitions in old style C to be modified.
In the Ada 9X design, we have succeeded in adopting a very conservative
approach. The few incompatibilities that exist can for the most part be dealt
with in a simple mechanical way. For example, the few new Ada 9X reserved
words require replacement in any Ada 83 program that uses them as identifiers.
A few other incompatibilities involve obscure or pathological programming
styles that we expect to appear very infrequently in existing code. The great
majority of programs will be unaffected by these changes and public-domain
tools are being developed to aid in their reliable detection.
In summary, few, if any, standard programming language revisions have ever
achieved 100% upward compatibility. We expect the few incompatibilities in
Ada 9X to cause very minor impact to existing code -- and for the overwhelming
majority of users, straightforward mechanical changes will correct the
inconsistencies.
(For more on this subject, see the papers "How to Program in Ada 9X, Using Ada
83" by Erhard Ploedereder and "Ada 9X Compatibility Guide" by Bill Taylor.
They're available on the AJPO host -- ajpo.sei.cmu.edu -- on the Internet;
look under the ada9x directory for files 9x-guide.txt or 9x-guide.ps, and
compat-guide.txt or compat-guide-10b-a4.rtf and compat-guide-10b-lt.rtf.)
Upcoming Presentations
We have many opportunities to present the latest status of Ada 9X in the
coming months including the Fifth Annual Software Technology Conference, 18-23
April in Salt Lake City, Utah; the National Conference, on Ada Technology,
15-18 March in Williamsburg, Va.; Object Expo, 20 April in New York City,
N.Y.; and Ada Europe 14-17 June in Paris, France.
Ada Lives!
I'm constantly amazed that many people still regard Ada as "that DoD
language." Ada is a widely accepted ANSI and ISO standard with over 22
countries using it for commercial as well as defense purposes. Applications
include the signaling on the Chunnel between the UK and France, the National
Census System in Singapore, the Reuters Money Management System, Boeing 777
avionics, the FAA Air Traffic Control System (under development), and the
Space Station Freedom. Also witness the interest and very active
participation of 12 countries in the Ada revision process.
So, the next time you sit though a panel discussing Ada's demise, please keep
in mind the very important reason why Ada lives -- complex software systems
need to be engineered. In these times of dwindling resources, this has never
been more true.
Ada Goes to College!
I've always maintained, if Ada is to continue to grow and prosper it must
become integrated into academia's curriculum. There is growing evidence of
this occurrence. Again, it's because academia is beginning to regard software
from a disciplined engineering perspective versus from a more theoretical
science perspective.
As of Dec. 92, over 373 universities/colleges are using/teaching Ada; with the
impending award of additional AJPO/DARPA grants, this figure will be boosted
even higher.
Ada 9X Reports Available
The Ada 9X Project Office maintains a mailing list for periodic distribution
of interim Ada 9X reports. The next report, "Introducing Ada 9X", will be out
by the time you read this. Contact my assistant, Robin Keeney, at the Ada 9X
Project Office to get on our mailing list if you are not already on it. You
can also send your address via e-mail to Ms. Keeney at keeneyr@plk.af.mil.
Many reports are also available electronically via our Ada 9X bulletin board
1-800-Ada9X-25 or on the AJPO host machine. In addition, if you want
day-by-day updates you can sign up to be an Ada 9X Volunteer Reviewer by
sending a message to ada9X-vr@ajpo.sei.cmu.edu.
Christine M. Anderson, Ada 9X Project Manager
Air Force Philips Laboratory/VTES
3550 Aberdeen Avenue, S.E.
Kirtland AFB, NM 87117-5776
505/846-0817, -0461; fax: 505/856-2290
e-mail: anderson@plk.af.mil
*******
Ada Information Clearinghouse (AdaIC)
P.O. Box 46593
Washington, DC 20050-6593
703/685-1477, 800/AdaIC-11, FAX 703/685-7019
adainfo@ajpo.sei.cmu.edu; CompuServe 70312,3303
The AdaIC is sponsored by the Ada Joint Program Office and operated by
IITResearch Institute.