BYTE Update: Ada and the Language Renaissance

BYTE Update: Ada and the Language Renaissance

[Martin Krischik]

Hi,

got this mail which I should forward. A nice positive article actually.

Martin
----------------------------------------------------------------------------
Martin,

I'm no longer subscribing to CLA; but are reading via Google Groups; so my
input bounces. The BYTE newsletter article below might be of interest to
the Ada community.

--sï¿œren
Sï¿œren Henssel-Rasmussen
Senior Software Engineer, TP.PCST.GTI.Cph
Frederikskaj, Copenhagen



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1. Ada and the Language Renaissance
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

by Shannon Cochran


The growth of the Internet has sparked a renaissance in 
computer language design. No longer confined to trading ideas 
at conferences or in academic journals, programming language 
aficionados can easily find each other in web forums and 
mailing lists. In this way "little"
languages like Ruby and Lisp have accumulated large, active 
communities of developers that continue to discover new uses 
for these technologies.

Another language that has benefitted from grassroots-level 
development is Ada. Back in 1995, the Department of Defense 
spent "probably tens of thousands of dollars" to sponsor the 
development of Ada 95, estimates Robert Dewar of AdaCore. Now 
Ada 2005 is coming out--and this time, the work was largely 
completed by volunteers, with some backing from vendors.

You probably haven't thought about Ada for a while, unless you 
write software for airplanes. But the language is alive and 
well. Designed in the 1970s to meet Department of Defense 
requirements for software reliability, Ada is still 
flourishing in industries that require large scale mission 
critical programs. And Dewar, of course, thinks that category 
could be expanded.

"There are lot of systems that--somebody may not drop dead if 
there's a bug, but the consequences could still be enormous," 
he points out.
eBay, he thinks, is a perfect example. As a 25 million dollar 
company that's absolutely dependent on a single program, "a 
company like eBay could perfectly well spend the resources to 
regard that as a critical program that MUST work," he says. 
"If we put our mind to it and use the right techniques and are 
willing to spend the resources, this general wisdom that all 
programs have bugs in them is not acceptable."

Ada is considered a more reliable language than Java or C 
because it features safe, high level memory management as well 
as a number of compile-time and run-time checks to help avoid 
bugs like buffer overflows or access to unallocated memory. 
The Ada 95 revision added object oriented features including 
dynamic dispatch to the language.
Ada 2005 isn't such a drastic overhaul: "It's not a huge 
earthquake change to the language, but it's got some important 
things in it,"
says Dewar. "It's mostly a collection of small smoothing out 
of things. If you have two packages with types that are 
dependent on each other...there was no good way to map those. 
And that problem is being completely solved by the 'limited 
with' feature, and that will be quite useful in its own right, 
but most useful for interfacing with
C++ and Java."

"It's really a unique thing that we've always worried about 
interfacing with Fortran, with C...C++ wasn't on the scene 
when we first did the language, but it is now," Dewar 
comments. "Now Ada and Java are very good friends in terms of 
language features and interfacing."

"It's mostly a matter of relatively small features that have 
been found to be really useful but annoying in practice," he continues.
"There's a notion in Ada of limited types...you're not allowed 
to assign between objects of these types. It's useful to have 
something between a [variable] and a constant. But a 
consequence of that is that you can't initialize these things 
and particularly you can't initialize it with aggregates. So 
we've added a feature for limited aggregates...a lot of things 
are in that category. The calendar feature now has full time 
zone support which it didn't have before."

AdaCore has implemented many of the new enhancements in its 
own GNAT Pro development environment. And other companies are 
also working to bring programmers better Ada tools. Aonix has 
developed an Eclipse plug-in, AonixADT, that brings 
Ada-project awareness, an Ada-language sensitive editor, 
Ada-language compile and build capabilities, and a complete 
Ada debugger interface to the Eclipse platform.

Ada 2005 is still officially in development, but Dewar says 
the technical work is done. "The wheels of standardization 
grind slowly,"
he laughs. It will be known as Ada 2005 until next year when 
it is formally approved by ISO: "and then it will just be Ada."

Shannon Cochran
Managing Editor
scochran@byte.com

http://www.byte.com/documents/s=9829/byt1127155273417/0919_cochran.html

-- 
mailto://krischik@users.sourceforge.net
Ada programming at: http://ada.krischik.com