Re: Is the Writing on the Wall for Ada?

[Marin David Condic <nobody@noplace.com>]

O.K. But let's make a couple of observations.

So far, there is no Conventional Ada Library so there is no version to skew.

I think I'd prefer to have some version to skew than no version at all.

Are we thinking the Conventional Ada Library is going to come out as 
part of the ARM? (Big mistake in my view) and/or that it is going to be 
on a TEN YEAR revision cycle (another big mistake in my view) so we're 
going to have staggered "standard" releases? I think if we're going to 
have a library, it ought to be something released once a quarter - or 
maybe every half - so is The Collective Vision to do something on a much 
bigger time frame? How would this allow Ada to react to changing 
circumstances with the relative speed of something like, oh, say, 
"Java"? From what I understand, Java's library is not an ISO standard 
that is revised every 10 years - its something far more dynamic than that.

I have consistently said that the library ought to be *outside* of the 
standard so you aren't complicating things for the standard. 
Fundamentally, this is absolutely no different than if I decide to use 
the Booch Components or Charles or some other container library. If they 
  (the nebulous "they" who are responsible for everything?) make a new 
release of the library, how does this impact anything in the Ada 
standard? If the Ada standard makes a new release, how does this affect 
anything in the Booch Components? (Assuming upward compatibility of the 
language) I'm only talking about doing something essentially like the 
Booch Components (except going beyond mere containers) and declaring 
that to be "The Answer" for Ada by including it with compiler deliveries.

If Ada0x plans on including a standard container library, then *yes* I 
can understand delaying the construction of a Conventional Ada Library 
until you get the new components on which you may want to build. But 
that's only the *construction* part - you could still be discussing what 
is going to be in the library, who is going to do the work, how it is 
going to be managed, etc. There ought to be a *lot* of preparation prior 
to committing to the use of some set of underlying tools. So if the ARG, 
et alia, are busy discussing things that might be either a) in the ARM 
or b) in the Conventional Ada Library and nobody has tossed the coin yet 
to decide which, you simply delay the committment to put it in the CAL 
until the ARG has made a new ARM and done its THING. QED. :-)

Assuming for a moment that a library is something the ARG, et alia, want 
to have and assuming that they see the near-divine wisdom of my position 
on keeping it out of the ARM, then it ought to be a Piece Of Cake to at 
least initiate some discussion about a) the fact that it should be 
brought about and getting the buy-in of the interested parties, b) what 
is the best way to manage the construction of it (SIGAda? Volunteers? 
Paid-Developers? Every-Vendor-For-Himself? Some combination of all of 
them?), c) if it should be a reference implementation or not (most/all 
vendors agreeing to accept an implementation made by whoever is 
annointed in "B"), d) what sort of time frame we're talking about for an 
initial build and subsequent releases, e) who would be making extensions 
and how, f) etc., etc., etc. There are a lot of "paperwork" details that 
could be worked out and people/organizations that could be lined up to 
do the job and it could all be done with no entanglement with the 
immanent Ada0y standard.

Just my thinking on it. I hate to see stuff get delayed if there is 
useful work that could be taking place.

MDC



Robert I. Eachus wrote:
> 
> 
> They have done that, and Matt for one has responded.  But there is a 
> complex issue known as version skew that has an effect here.  Version 
> skew is when you have a project that depends on two different standards, 
> call them Foo and Bar.  Any new version of Foo will depend on the 
> existing version of Bar, and vice-versa.  So if the current versions are 
> Foo3 and Bar4, Foo3 could be designed for Bar3 and Bar4 for Foo2, and 
> there is no way to use the most recent versions of both.  The solution 
> of course is when the standards are that closely coupled, to update them 
> and reissue them together.
> 
> The problem with version skew though is not when two standards are 
> involved.  Version skew becomes ugly somewhere between three and five 
> standards.  With two standards, there are always two pairings you can 
> use, either the most recent Foo, and the version of Bar it depends on, 
> or the most recent Bar, and the Foo it was designed to use.  With three 
> standards, the possibility exists, but is remote, that there is no 
> consistant set of standards you can use.  With five, there are twenty 
> potential relations to be satisfied and only five discrete variables. 
> Unless someone has specifically considered the group of standards you 
> are using, or some of the standards are totally independent, version 
> skew will kill you.
> 
> That is why there will almost certainly be a component library in Ada 
> 0Y.  Not because it needs to be there but because having it there 
> eliminates one possibility of version skew.  The same for a database 
> interface, and the same for all the annexes that were added to Ada 95. A 
> component library is one thing that many other libraries will depend on, 
> so is a database interface, so is a graphics binding.  Bringing as many 
> of these as possible under the Ada standard tent will make it easier to 
> use Ada with domain specific standards, like a test standard, or a 
> guidance system standard, or an aerodynamics standard and so on.
> 


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Marin David Condic
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