BYTE Update: Ada and the Language Renaissance
- From: Martin Krischik <krischik@xxxxxxxxxxxxxxxxxxxxx>
- Date: Tue, 20 Sep 2005 18:24:44 +0200
got this mail which I should forward. A nice positive article actually.
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.
Senior Software Engineer, TP.PCST.GTI.Cph
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
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."
Ada programming at: http://ada.krischik.com
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