Re: C/C++ cheaper than Ada?? how? Re: Ada 200X

Re: C/C++ cheaper than Ada?? how? Re: Ada 200X

[Sam Harbaugh, Palm Bay, Florida]

re: cheaper - This spring the project I am on was directed by the DoD
customer to switch from Ada95 to C++.  The customer perceives that C++ is
less expensive than Ada95.  I will wait at least a year to give an opinion
on relative cost.  If you haven't looked at C++ in a while look again, the
draft standard ANSI/ISO C++ has new features.

re: Ada 200X - I suggest: 1) Recognize that it is a multilingual world,
accomodate other popular languages. The program I am on is a C++ project
but actually there are 13 programming languages to be used. 2) Recognize
that it is a multi-architecture world, accomodate interpretive systems and
systems which don't admit programs which have runtime systems.

my 2 cents - worth every penny

Re: C/C++ cheaper than Ada?? how? Re: Ada 200X

[Dr Richard A. O'Keefe]

Sam Harbaugh, Palm Bay, Florida wrote:
> If you haven't looked at C++ in a while look again, the
> draft standard ANSI/ISO C++ has new features.

Which will, of course, be useless in *portable* programs until 3 to
5 years after the standard is finalised, if the history of C89 is
any guide.

As things are right now, a student here developed a really snazzy
package on system X using "C++" compiler Y and gave it to me on a
system Z disc, but the "C++" compiler W on that system choked and
died on it.  That really is the typical C++ experience these days.
One hopes that the eventual existence of (a screamingly complex)
standard (still lacking a lot of useful Ada stuff) will change
things, but as I'm _still_ waiting for one particular vendor to
support something that has been pretty much unchanged in C++ drafts
for several years now, I wouldn't hold your breath.
 
> re: Ada 200X - I suggest: 1) Recognize that it is a multilingual world,
> accomodate other popular languages.

Ada 95 _already_ recognised that, in a far more effective way than
any other programming language standard yet in existence.  (Mind you,
there isn't an _official_ interface between Ada and REXX or Visual
Basic, but neither is there an official C++ interface to those things.)
There _is_ an Ada CORBA binding...

Re: C/C++ cheaper than Ada?? how? Re: Ada 200X

[Robert Dewar]

<<re: Ada 200X - I suggest: 1) Recognize that it is a multilingual world,
accomodate other popular languages. The program I am on is a C++ project
but actually there are 13 programming languages to be used. 2) Recognize
that it is a multi-architecture world, accomodate interpretive systems and
systems which don't admit programs which have runtime systems.
>>

I find this puzzling. Ada 95 is the ONLY language to systematically
accomodate other languages, and it goes very far in this respect. If you
have specific suggestions for improvements in this area, fine, but to
somehow suggest that Ada 95 dos NOT accomodate other popular languages
seems bizarre.

Ada is perfectly interoperable with interpretive systems. Usually these
days, that is a code word for Java. The fact that two separate vendors
of Ada compilers are providing Ada compilers that generate JBC should
be an indication that this is not a problem.

As for "don't admit programs which have runtime systems". There is nothing
about Ada that requires that every Ada program needs a runtime system. Indeed,
GNAT provides a capability, which we call GNORT (GNAT with No RUntime) that
does what it says. Allows the compilation of programs with absolutely no
runtime. Obviously this means that there are restrictions in the subset
that can be used, but it is a pretty big subset (much bigger than SPARKI
for example), and in the Java Byte Code context, GNAT will accomdoate
the Ravenscar tasking model, again with zero runtime.

So I really don't see what the quote above is asking for, and I certainly
don't see any substantial issues to be addressed in Ada 200X here. Again,
if there are specific suggests rather than what appear to be ill-informed
generalizations, then that would be very helpful!

Robert Dewar
Ada Core Technologies

Re: C/C++ cheaper than Ada?? how? Re: Ada 200X

[Larry Kilgallen]

In article <dewar.900353937@merv>, dewar@merv.cs.nyu.edu (Robert Dewar) writes:

> As for "don't admit programs which have runtime systems". There is nothing
> about Ada that requires that every Ada program needs a runtime system. Indeed,
> GNAT provides a capability, which we call GNORT (GNAT with No RUntime) that
> does what it says. Allows the compilation of programs with absolutely no
> runtime. Obviously this means that there are restrictions in the subset
> that can be used,

Not so obvious to some of us.  Please elaborate.

Larry Kilgallen

Re: GNORT

[Robert Dewar]

Markus asks

<<How is this activated in GNAT? Do I just have to write something like

  pragma Restrictions(No_Exceptions, Max_Tasks => 0);

and the run-time system is gone?
>>

this = GNORT


No, it is a special pragma (pragma No_Runtime)
(it is equivalent to a set of restrictions, plus does some other things!)

Re: C/C++ cheaper than Ada?? how? Re: Ada 200X

[ak]

kilgallen@eisner.decus.org (Larry Kilgallen) writes:

> In article <dewar.900353937@merv>, dewar@merv.cs.nyu.edu (Robert Dewar) writes:
> 
> > As for "don't admit programs which have runtime systems". There is nothing
> > about Ada that requires that every Ada program needs a runtime system. Indeed,
> > GNAT provides a capability, which we call GNORT (GNAT with No RUntime) that
> > does what it says. Allows the compilation of programs with absolutely no
> > runtime. Obviously this means that there are restrictions in the subset
> > that can be used,
> 
> Not so obvious to some of us.  Please elaborate.

I guess all features related to tasking (protected types, the task type)
are gone. Exceptions need moderate run time system support, so maybe they
are gone too (?)

-Andi

Re: GNORT

[Markus Kuhn]

Robert Dewar wrote:
> As for "don't admit programs which have runtime systems". There is nothing
> about Ada that requires that every Ada program needs a runtime system. Indeed,
> GNAT provides a capability, which we call GNORT (GNAT with No RUntime) that
> does what it says. Allows the compilation of programs with absolutely no
> runtime.

How is this activated in GNAT? Do I just have to write something like

  pragma Restrictions(No_Exceptions, Max_Tasks => 0);

and the run-time system is gone?

Markus

-- 
Markus G. Kuhn, Security Group, Computer Lab, Cambridge University, UK
email: mkuhn at acm.org,  home page: <http://www.cl.cam.ac.uk/~mgk25/>

Re: C/C++ cheaper than Ada?? how? Re: Ada 200X

[Larry Kilgallen]

In article <m3btqs39lg.fsf@fred.muc.de>, ak@muc.de writes:
> kilgallen@eisner.decus.org (Larry Kilgallen) writes:
> 
>> In article <dewar.900353937@merv>, dewar@merv.cs.nyu.edu (Robert Dewar) writes:
>> 
>> > As for "don't admit programs which have runtime systems". There is nothing
>> > about Ada that requires that every Ada program needs a runtime system. Indeed,
>> > GNAT provides a capability, which we call GNORT (GNAT with No RUntime) that
>> > does what it says. Allows the compilation of programs with absolutely no
>> > runtime. Obviously this means that there are restrictions in the subset
>> > that can be used,
>> 
>> Not so obvious to some of us.  Please elaborate.
> 
> I guess all features related to tasking (protected types, the task type)
> are gone. Exceptions need moderate run time system support, so maybe they
> are gone too (?)

Well I didn't take "no run time" to mean "no operating system",
but even if it does, an Ada compiler could emit the necessary
instructions as part of the image to do tasking.

I am not saying it is cost-effective for a particular market
situation, but it is not a technical impossibility.

Are the GNORT restrictions just pragmatics, or are there technical
limits?

And by "no runtime" is it meant "no operating system" ?

Larry Kilgallen

GNORT

[Tramse]

Are their many users of GNORT?  Does anyone have experience in running GNORT on
Linux with a 68K target?  Are their any debugging tools?

Re: GNORT

[Robert Dewar]

In article <19990514155154.03860.00000397@ng-cr1.aol.com>,
  tramse@aol.com (Tramse) wrote:
> Are their many users of GNORT?  Does anyone have experience in
> running GNORT on Linux with a 68K target?  Are their any
> debugging tools?

GNORT is the GNAT No-Run-Time technology, which allows GNAT to
generate programs for a subset of Ada with absolutely no
run-time being used at all, not even one byte.

The subset is comparable to SPARK-95, with the notable point
that full generics are allowed. GNORT is intended specifically
for safety-critical use where certification is an issue (for
other embedded applications without this requirement, it is
usually more appropriate to consider a larger subset of Ada,
for example that provided by the restricted run-time option
in GNAT, which roughly corresponds to the Ravenscar profile.
This will be fully supported in version 3.12.

There is one large scale user of GNORT technology to develop
a large safety critical program. They are using an OS/2 host
and a bare x86 board. Using a Linux host would be essentially
identical to this. This project has been going for a while, and
is the one for which GNORT technology was originally developed.

A number of other customers have started using GNORT more
recently (this is fairly recent technology).

As for debugging tools, GNORT generates standard format object
modules, and any tool chain can be used to deliver and debug
the result. Note that the GNAT approach of using C-compatible
debugging information (which encodes the Ada information needed)
means that a C-based debugger can be used to debug GNAT code.
Another approach is to use the VxWorks environment, where in the
final delivery, the VxWorks kernel is simply excluded, but
during development, the standard GnatWorks debugging interface
can be used (several GNORT customers have adopted this
approach).

Since GNORT applications tend to be specialized, the best way to
pursue the question of whether a specific application is a
sensible match for GNORT technology is to send mail to
sales@gnat.com or sales@act-europe.fr outlining your interest,
and we can have an appropriate technical person contact you to
discuss your specific application.

Robert Dewar
Ada Core Technologies


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