RE: SIGada Conference

RE: SIGada Conference

[amado.alves]

"It is possible to make fancy use of generics and dispatching so that you 
can have one specification matched by different bodies....
Interfaces allow a programmer 
to say he is doing just that, and doing it intentionally."

Formal packages provide that.

Anyway, I'm ok with interfaces per se. I just worry that they might push other (for me more interesting) additions off the list (e.g. container library) given the scarse revision resources.

/* Tangent but doubly related issue: increasing the power of generics viz. towards generic parameters would be also a more interesting addition to me. I mean to be able to pass a generic unit to a (mandatorily generic) unit. I came across many situations where this would be useful. */

RE: SIGada Conference

[amado.alves]

>>> : ... Java-style interfaces...
>> 
>> I'm surprised this one is still being listed. It has been shown to
>> be completely unnecessary.
>
> Ok, I'll byte. "Shown" where?

By *the* Ada guru J.-P. Rosen in Ada-Europe 2001 or 2002. And I seem to remember in the ARG discussions also, but I'll have to check.

> Personally, I
> think Java-style interfaces will let me do things I simply cannot do
> now.

That's what has been shown. That all those "things" can be done in Ada now. With either (yes) access discriminants which some say it's the golden nugget of Ada or, my favourite, formal packages. And mixins. And combinations thereof.

But please do come up with a new "thing" that cannot be done in Ada now.

"Java-style interfaces" is a poor man's multiple inheritance. I'd love to see fully fledged (linguistic) MI in Ada 2005, but *that* is too hard to define and implement. So I'm happy without it. But in that case I don't want the fake MI either.

Re: SIGada Conference

[Stephen Leake]

"amado.alves" <amado.alves@netcabo.pt> writes:

> : The Ada 200Y features sound fun...
> : ... Java-style interfaces...
> 
> I'm surprised this one is still being listed. It has been shown to
> be completely unnecessary.

Ok, I'll byte. "Shown" where?

Since the ARG people are _very_ smart, and _very_ motivated to
conserve implementors time, I suspect you are wrong :). Personally, I
think Java-style interfaces will let me do things I simply cannot do
now.

-- 
-- Stephe

Re: SIGada Conference

[Robert I. Eachus]

Stephen Leake wrote:

> Since the ARG people are _very_ smart, and _very_ motivated to
> conserve implementors time, I suspect you are wrong :). Personally, I
> think Java-style interfaces will let me do things I simply cannot do
> now.

Thanks for the compliment.  But I think everyone should be aware that we 
don't care whether or not a feature is "necessary."  What we really 
agonize about is how to make programming in Ada easier and make it more 
likely that Ada programs will satisfy all the "ilities."

The interfaces proposal allows a style of multiple inheritance that is 
currently not well supported in Ada.  Wonderful.  But the reason that it 
is a slam dunk that it will be in there, even if it does result in 
adding a new reserved word, is that it makes in much easier in many 
cases for a programmer to document what he is really trying to do.

It is possible to make fancy use of generics and dispatching so that you 
can have one specification matched by different bodies.  But the fact 
that different members of a class are handled in very different ways is 
hidden in the structure of the program.  Interfaces allow a programmer 
to say he is doing just that, and doing it intentionally.

For example you can have an indexed list type that calls different sort 
routines, hash table, radix sort, b-tree, etc. depending on the type of 
the index.  With interfaces the "documentation" of this occurs where the 
interface is implemented for a specific type of index, rather than where 
the index types are declared.  (And you don't need to manufacture a 
tagged parent type to make it work.)

-- 
                                           Robert I. Eachus

"The war on terror is a different kind of war, waged capture by capture, 
cell by cell, and victory by victory. Our security is assured by our 
perseverance and by our sure belief in the success of liberty." -- 
George W. Bush

Re: SIGada Conference

[Robert C. Leif]

Since I am now the Chair of the Commercial Ada User's Group, CAUWEG, I
would like to add some comments form the view of commercial
utilization of Ada. Parenthetically, I hope that it is not the case
that I am both the Chair and the only member of CAUWEG.

There were 3 main threads at the meeting. The first was the obvious
success of SPARK including its use for real-time. The second was the
proposed object oriented additions to Ada; and the third was A# for
the .Net environment. There is an obvious difference between those who
are very interested in SPARK and those who are interested in object
oriented extensions to Ada. The emphasis in SPARK is provable,
efficient software which resides on the stack. The OO group wants to
create better OO capabilities in Ada.

Unfortunately, except for a talk by David Wheeler, there was no desire
from the ARG or WG9 or mention of "to make programming in Ada easier"
except for the OO paradigm. David Wheeler suggested adding a With and
Use Clause. This would allow one to write the package name only once.
Although I do not like the presence of a Use clause at the beginning
of a package; I, at least, favor efficient sinning. I would complement
this with a With and Renames Clause. With D renames A.B.C.D; Of even
greater significance is the omission of the GNAT 'img. The use of 'img
saves keyboarding and should make the sources easier to read.

I believe once SPARK includes the use of generics that can be
instantiated at compile time and class wide dispatching that occurs at
compile time, it will become a significant competitor to classic Ada.
Parenthetically, SPARK presently allows one to mix SPARK and Ada.

As for C#, I still believe that it is Ada's great hope. Unfortunately
since it is being developed in an academic setting, the Air Force
Academy; it has the characteristics of the university research product
that it is. A# is a brilliant innovation, but its lack of the final
touches needed for commercialization will greatly impede its present
use. The install is complex and to my dismay representation
specifications have not yet been implemented. I hope that some
commercial group takes over this product and delivers it for our use.

In a separate note, I will report on the XML section of the Birds of a
feather on APIs.

Bob Leif

"Robert I. Eachus" <rieachus@comcast.net> wrote in message news:<DaudnfwlSK39VkKiRVn-sQ@comcast.com>...
SNIP
> "Thanks for the compliment.  But I think everyone should be aware that we 
> don't care whether or not a feature is "necessary."  What we really 
> agonize about is how to make programming in Ada easier and make it more 
> likely that Ada programs will satisfy all the "ilities."
SNIP>

RE: SIGada Conference

[amado.alves]

: The Ada 200Y features sound fun...
: ... Java-style interfaces...

I'm surprised this one is still being listed. It has been shown to be completely unnecessary.

Re: SIGada Conference

[Georg Bauhaus]

amado.alves <amado.alves@netcabo.pt> wrote:
: : The Ada 200Y features sound fun...
: : ... Java-style interfaces...
: 
: I'm surprised this one is still being listed. It has been shown to be completely unnecessary.

where?

Re: SIGada Conference

[Hyman Rosen]

Georg Bauhaus wrote:
> amado.alves <amado.alves@netcabo.pt> wrote:
> : : ... Java-style interfaces...
> : I'm surprised this one is still being listed. It has been shown to be completely unnecessary.
> where?

I expect this is just the usual "simulate MI with access discriminants"
bit that always comes up here. I think it can do everything except support
cross-casting.

Re: SIGada Conference

[Jean-Pierre Rosen]

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"Hyman Rosen" <hyrosen@mail.com> a �crit dans le message de news:1071613043.278647@master.nyc.kbcfp.com...
> Georg Bauhaus wrote:
> > amado.alves <amado.alves@netcabo.pt> wrote:
> > : : ... Java-style interfaces...
> > : I'm surprised this one is still being listed. It has been shown to be completely unnecessary.
> > where?
>
> I expect this is just the usual "simulate MI with access discriminants"
> bit that always comes up here. I think it can do everything except support
> cross-casting.
>
It can. See my paper at http://www.adalog.fr/publicat/ada-interfaces.pdf

-- 
---------------------------------------------------------
           J-P. Rosen (rosen@adalog.fr)
Visit Adalog's web site at http://www.adalog.fr

Re: SIGada Conference

[Hyman Rosen]

Jean-Pierre Rosen wrote:
> "Hyman Rosen" <hyrosen@mail.com> a �crit
>>I expect this is just the usual "simulate MI with access discriminants"
>>bit that always comes up here. I think it can do everything except support
>>cross-casting.
> 
> It can. See my paper at http://www.adalog.fr/publicat/ada-interfaces.pdf

Does this mean that you think it can support cross-casting,
or do you agree that it cannot? That is, in Java, I may have
two interfaces:
     interface IF_1 { }    interface IF_2 { }
and given an object of type IF_1, I may try to see if it is
also of type IF_2:
     boolean is_both(IF_1 o) { return o instanceof IF_2; }
and if it is, I can cross-cast:
     IF_2 as_IF_2(IF_1 o) { return is_both(o) ? (IF_2)o : null; }

Note that I can do this without any knowledge at all of the
existence of one or more parent types which implement both
interfaces. I don't think this can be done with the inner class/
access discriminant approach.

Re: SIGada Conference

[Jean-Pierre Rosen]

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"Hyman Rosen" <hyrosen@mail.com> a �crit dans le message de news:1071687303.254780@master.nyc.kbcfp.com...
> Jean-Pierre Rosen wrote:
> > "Hyman Rosen" <hyrosen@mail.com> a �crit
> >>I expect this is just the usual "simulate MI with access discriminants"
> >>bit that always comes up here. I think it can do everything except support
> >>cross-casting.
> >
> > It can. See my paper at http://www.adalog.fr/publicat/ada-interfaces.pdf
>
> Does this mean that you think it can support cross-casting,
> or do you agree that it cannot? That is, in Java, I may have
> two interfaces:
>      interface IF_1 { }    interface IF_2 { }
> and given an object of type IF_1, I may try to see if it is
> also of type IF_2:
>      boolean is_both(IF_1 o) { return o instanceof IF_2; }
> and if it is, I can cross-cast:
>      IF_2 as_IF_2(IF_1 o) { return is_both(o) ? (IF_2)o : null; }
>
> Note that I can do this without any knowledge at all of the
> existence of one or more parent types which implement both
> interfaces. I don't think this can be done with the inner class/
> access discriminant approach.
>
What I meant is that if class A implements interface IF, and you get an object as an IF, you can get a view of it as an A. I didn't
consider the case you mention - presumably because I never met a need for it!

-- 
---------------------------------------------------------
           J-P. Rosen (rosen@adalog.fr)
Visit Adalog's web site at http://www.adalog.fr

Re: SIGada Conference

[Hyman Rosen]

Jean-Pierre Rosen wrote:
 > presumably because I never met a need for it!

I think it has its place in some low-level framework
code, as a means of querying whether an object supports
a particular interface. In any case, it's an ability
that exists with MI or interfaces, and you need to know
about it when thinking about ways to emulate those
features without fully supporting them. Typically, this
kind of interface querying involves a runtime search in
the type information structure or virtual table of the
object being examined, and that's not available in the
homebrew version.

Re: SIGada Conference

[Martin Dowie]

"amado.alves" <amado.alves@netcabo.pt> wrote in message
news:mailman.125.1071600001.31149.comp.lang.ada@ada-france.org...
: The Ada 200Y features sound fun...
: ... Java-style interfaces...

> I'm surprised this one is still being listed. It has been shown to be
completely unnecessary.

Sorry, I just don't buy this - if from only an IDE point of view.

SIGada Conference

[Chris Miller]

Anyone care to post a summary of what went on at this conference.

Anything interesting ???

Chris Miller

Re: SIGada Conference

[Stephen Leake]

chrismiller677@hotmail.com (Chris Miller) writes:

> Anyone care to post a summary of what went on at this conference.
> 
> Anything interesting ???

The most interesting thing was that there are several companies making
money using Ada, and they are all growing :).

I've been more inspired to look into using SPARK to write solid code.

The Ada 200Y features sound fun, too; aggregates for limited types, a
solution for mutually recursive types, Java-style interfaces, no more
silent overloading when overriding was meant.

If you subscribe to Ada Letters, the proceedings should appear in a
few months :).

-- 
-- Stephe

Re: SIGada Conference

[Georg Bauhaus]

Stephen Leake <stephen_leake@acm.org> wrote:
: 
: The Ada 200Y features sound fun, too; aggregates for limited types, a
: solution for mutually recursive types, Java-style interfaces, no more
: silent overloading when overriding was meant.

Anything new about pre/post conditions?


-- Georg

Re: SIGada Conference

[Stephen Leake]

Georg Bauhaus <sb463ba@l1-hrz.uni-duisburg.de> writes:

> Stephen Leake <stephen_leake@acm.org> wrote:
> : 
> : The Ada 200Y features sound fun, too; aggregates for limited types, a
> : solution for mutually recursive types, Java-style interfaces, no more
> : silent overloading when overriding was meant.
> 
> Anything new about pre/post conditions?

Nope. I think 'pragma Assert' will be standardized, but that's about it.



-- 
-- Stephe

Re: SIGada Conference

[Marin David Condic]

That can easily be misleading. Its possible that some companies are 
growing by getting a larger share of a shrinking pie. As some companies 
abandon Ada as a business venture, others pick up whatever share they 
may have had and show signs of "Growth" - but it doesn't imply Ada is 
necessarily doing well.

I'd like to see Ada get somewhere, but there needs to be a better metric 
than the business growth of some few companies. Jobs in Ada, new project 
starts in Ada, classes taught in Ada, etc. Any of those would be a beter 
metric - unless you could get total revenues for all companies doing Ada 
business (and even that would miss use of Ada in internal work by big 
companies like Boeing, Lockheed, etc.) In any event, its tough to get 
those metrics so we're still left with perceptions and best guesses. My 
perception is that Ada has been in general on the decline and had better 
do something to excite the world if it wants to be around with any real 
strength in another ten years.

MDC


Stephen Leake wrote:
> 
> The most interesting thing was that there are several companies making
> money using Ada, and they are all growing :).
> 



-- 
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