From: britt.snodgrass@...
Date: 2008-04-16T01:35:07+09:00
Subject: Re: Ada vs Ruby

On Apr 15, 6:26 am, Marc Heiler <sheve...@linuxmail.org> wrote:
> Hi,
>
> Onhttp://www.gcn.com/print/27_8/46116-1.htmlAda is touted briefly.
>
> The sentence(s) that most jumped into my eye (and hurt my brain a bit)
> was this:
>
> "[...] Ada has a feature called strong typing. This means that for every
> variable a programmer declares, he or she must also specify a range of
> all possible inputs.[...]"
>

I am an Ada programmer.  The quoted statement from the GCN article is
not correct as written - "must" should be "may".  Many languages
including C++ and Java, claim to be strongly typed.  Strong typing is
a very desirable language feature.  One key difference with Ada is
that Ada supports strong typing and optional range constraints of
primitive (e.g. integer, fixed point and floating point) types.

> "[...] This ensures that a malicious hacker can't enter a long string of
> characters as part of a buffer overflow attack or that a wrong value
> won't later crash the program. [...]"
>
> But clearly that is simple to do in ruby as well (and I never heard of a
> buffer overflow outside of the C world anyway): Just specify which input
> range would be allowed and discard the rest, warn the programmer, or
> simply convert it to the nearest allowed value - am I missing on
> something? Maybe there are some other reasons why Ada is still so en
> vogue for aviation software but I dont really get it (other than legacy
> code that was sitting there for thousand of years already). Maybe it is
> a paradigm that is only possible in Ada.
>
> Ruby being too slow would be something I could not quite understand
> insofar that, after all you could write parts in C anyway, or you could
> use (in the case of replacing ADA) Lua - I'd figure Lua would be quite
> fast. Somehow despite that Ada is still in use, to me it seems like a
> "dead" language (means noone really learns it because there are better
> alternatives available)

Ada is far from dead - its a great general purpose language and is
currently being used on new projects.  In the high assurance domains
where it is principally used, there is currently nothing better,
certainly not C++ or Java.  There also exists the SPARK
(www.sparkada,com) subset of Ada and its associated set of formal
methods based static analysis tools.  I use SPARK and, though it
requires a certain mindset to use effectively, I think its the "real
deal" for producing the highest quality code (i.e., free of initial
defects).  We really don't expect to find many bugs during debugging
or formal testing, at least not many bugs that can't be traced back to
a missing or ambiguous requirement.

>
> The biggest confusion I get here is simply that strong typing is touted
> as a very good thing to have. I dont know if this is the case or not,
> but it seems to me that this is more "behaviour" that is imposed onto
> the programmer anyway (as in, he must do extra work to ensure his
> variables are a certain way etc..)
> For example, the "strong typing" as described here appears to me more a
> "force the programmer to do this and that". This may have advantages in
> the long run, I dont know, maybe fewer bugs or no buffer overflow
> problems, but to me it still is forcing the programmer to comply. I dont
> get what is so great about having to worry about many details. And on
> blogs you do sometimes see proponents of this solution scold on the
> people that use another solution (not only typing, but also test driven
> development and so on...)
> --
> Posted viahttp://www.ruby-forum.com/.

"worry about many details" isn't great fun but its necessary for
safety and/or security critical software.  If a well specified
programming language and its associated compilers/ static analysis
tools help me to manage the details all the way from the big picture
design down to bit-level ASIC interfaces, then I welcome the help.

- Britt