Re: "Subtract C, add Ada"

[ka@socrates.hr.att.com (Kenneth Almquist)]

In article <862035D1F1C@annwfn.com>, Fred McCall <merlin@annwfn.com> wrote:
> In <D1Msq8.4Hs@inmet.camb.inmet.com> mg@asp.camb.inmet.com Mitch Gart writes:
>
>> Ada leaves less room for single-keystroke
>> errors, such as the common C error of using = (assignment) instead of
>> == (comparison); 
>
> I've always been curious.  Just *where* is this a "common C error"?
> I've seen lots of beginners and non-C programmers claim it is, but I
> don't recall ever hearing of anyone who knew what they were doing (and
> who was using a real tool -- say, lint -- to check their code) making
> it. 

I confuse "=" and "==" periodically even though I've used C for years.

I generally don't use lint.  I just ran this "real tool" on the program:

   #include <stdio.h>
   #include <stdlib.h>

   main(int argc, char **argv) {
       printf("hello, world\n");
       exit(0);
   }

The result is four useless messages:

   hello.c(4): syntax error at or near type word "int"
   hello.c(7): warning: main() returns random value to invocation environment
   exit value declared inconsistently	llib-lc(236)  ::  hello.c(6)
   printf returns value which is always ignored

>> its type-abstraction facilities reduce the need for
>> error-prone pointer manipulation; 
>
> Afraid this one doesn't seem to make sense.  How does being able to
> define a dozen incompatible types of integer "reduce the need for
> error-prone pointer manipulation"?  

I'm not sure what was intended here either.  Ada has generic packages
and procedures, which makes it easier to write type-safe library routines
which manipulate pointers.

>> and its modular facilities improve
>> teams' coordination of effort.
>
> Both languages are modular.  I'm not sure how this is a 'win' unless
> we're talking about totally inexperienced teams.

I took a software engineering course in which included a group project.
The group I was in defined all of the interfaces in Modula 2.  Some of
the code was written in C because nobody on the project knew Modula 2
well, but I don't think we would have had a chance of completing the
project in the ten weeks allotted if we hadn't used Modula 2 for the
interfaces.

>> This experience, McCormick notes, "has convinced all my faculty
>> colleagues to support teaching Ada in our beginning courses.  This
>> spring semester, the first student with Ada as their mother tongue
>> will enroll in my course.  I can only imagine what these teams will
>> accomplish".
>
> Well, Ada is certainly a better choice than C for a beginning language
> to teach design concepts, etc. However, that isn't necessarily saying a
> whole lot, since that wasn't what C was intended for. I'm also not sure
> why that would be considered a 'plus', unless the idea behind Ada was to
> come up with a good language for beginners; that wasn't the idea behind
> it.

C was intended for (or at least the early feedback on its design came
from) programmers writing individual programs.  In contrast, Ada was
explicitly designed to support multi-person projects.  It is nice to
see that the relative usefulness of these languages for group projects
reflects the intentions of the language designers.
				Kenneth Almquist