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The Return of Ada
Pickens writes "Today when most people refer to Ada it's usually as a cautionary tale. The Defense Department commissioned the programming language in the late 1970s but few programmers used Ada, claiming it was difficult to use. Nonetheless many observers believe the basics of Ada are in place for wider use. Ada's stringency causes more work for programmers, but it will also make the code more secure, Ada enthusiasts say. Last fall, contractor Lockheed Martin delivered an update to ERAM, the Federal Aviation Administration's next-generation flight data air traffic control system — ahead of schedule and under budget, which is something you don't often hear about in government circles. Jeff O'Leary, an FAA software development and acquisition manager who oversaw ERAM, attributed at least part of it to the use of the Ada, used for about half the code in the system."
In school. It wasn't actually any different from very many other languages that have huge class libraries, it's just that they were all 'included' in the langauge instead of linked in separately. It's more verbose and stuff, but I didn't see any completely foreign concepts in Ada that aren't around in most other langauges. Just more typing, from what I remember.
Speak for yourself.
I took a class in Ada for a previous employer. I found it a lot like Pascal and not all that difficult. The main issue was the cost of compilers which had to go through an expensive certification process. I did find the language a but verbose for many things, e.g. here
The real issue isn't that it's hard to learn, it's that it's a little cumbersome, but more importantly, not many people know it and they typical clueless manager wants to see 10+ years of Ada experience on the resume/cv before hiring someone. Those people are few and far between, but and competent software developer can learn it.
I don't know, but it works for me.
Oddly, they're saying a language which is slower for people to write, and considerably more obscure than most languages, is the reason something is done under-budget and quickly? It seems like those traits would make it more secure, but take much longer to make...
You need to make a distinction: they weren't writing new code, they were updating existing code. This is a very important distinction. We are all aware of "code rot", etc. and how over time documentation gets lost, people have to re-learn a piece of code based purely on the source, etc. However they took an older piece of code and revamped it, right on time and under budget. This is notable, and may be attributable to some of the properties of Ada.
Maybe, maybe not, but there's a good chance it had something to do with Ada.
It was the first Ariane V launch. They had reused software from an earlier model of the Ariane without properly testing it in its new environment. Think of it this way, you take the speedometer module from your Trabant and install it in a Ferrari. The first time that you exceed 100 km/h, the speedometer module fails with an overflow error because the type for speed was defined as 0..100. The problem was that Ariane's management was cutting corners on requirements analysis and testing. The software performed as designed, it just wasn't designed for the Ariane V.
Mea navis aericumbens anguillis abundat
The old 16-bit gyroscope controller was replaced with a 32-bit one but the software was kept the same. The software got an invalid input, diagnosed it as a fault and shut itself down. The backup was brought online, got an invalid input, and shut itself down. At this point, the system determined that the rocket was unsafe and caused it to self destruct. By this point, it was already at a higher altitude than the gyroscope was intended to operate (the V accelerated faster and so got above this threshold much faster than the IV).
I am TheRaven on Soylent News
I was grabbing someone's .sig and stuffing it into my "quotes" file, and found this relevant tidbit...
Imagine a surgeon who discovers how much money can be saved by purchasing Xacto blades instead of using blades manufactured to more stringent standards. That is exactly the situation we are currently facing when contractors decide to use C or C++ instead of Ada. On the surface one gets the same result. It is only that superficial result that counts for the lowest bidder.
- Richard Riehle
The living have better things to do than to continue hating the dead.
Source:http://www.oss-in-atm.info/20051207/09-gasperoni.php
I am Oliver E Cole, the president of OC Systems (oec@ocsystems.com). The Ada compiler and associated tools used by ERAM is PowerAda, done by OC Systems. We have worked closely over a number of years with the ERAM project and its predecessors. Yup, they are using Ada because of all its robustness and features, but they also have a good mature software development process. Part of a muture process is choosing the right language and tools for the job. Sometimes php is the right choice, sometimes C, C++ and sometimes Ada. For a project like Air Traffic Control (very long lived, high quality) a strong argument can be made for Ada. Ada catches a lot of errors "automatically" and is designed for big systems.
You could say it's slower to write, but it's not that slow.
Ada:
IF a AND b THEN
c;
d;
e;
END IF;
C:
if (a && b) {
c;
d;
e;
}
Ada tends to use words instead of symbols. Does it take longer to type? Yeah, a little. But this doesn't make it hard or obscure. In fact, it makes it much easier for non-programmers (and new programmers) to read and understand the code.
Why would you care about non-programmers? Because in the real world, programs are written to offer real world solutions. It helps if these programs can be reviewed by engineers, scientists, accountants, etc... who may not know every language, but can figure out the basic logic if it uses words instead of symbols. Also, the improved readability makes future changes less painful.
What happens if a coworker used & instead of && in the C version? It's a lot harder to make those kinds of mistakes in Ada.
For example, suppose you want to add a new value to an enumeration. As long as you adopt certain style conventions (avoiding default clauses) if you miss any places where you need to deal with it, you will get an error at compile time.
The overloading rules work well too because the result type is also involved in overload resolution. So you can have i := foo(); and a := foo(); call different foo's if i and a are different types. If i and a start out the same type and later one of them has to change, you just change it and you will get an error message on the call to foo that you need to fix until you provide the missing implementation.
Plus the fact that you have modules and a good system (in Ada 95) for hiding implementations, and a much better controlled system of generics than in C++ means you have better control over your system. You are never going to have your executable blow up from 10 M to 200M overnight because you added a template declaration.
As for verbosity, it really isn't. More perhaps than C/C++ but nothing like COBOL. However it does pay to use a slightly more verbose style than is absolutely essential by always fully qualifying names, but the same is true in C++.
The one weirdness that catches out beginners is that arrays passed as parameters retain their lower bound. So when dealing with substrings, for example, you have to be prepared for non-zero (or 1) lower bounds. But its easy to do.
Squirrel!
Hoare later recanted this bit, and strongly recommended the language as a foreward to one of its textbooks.