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Internet Message Format | 1996-08-05 | 3.6 KB

Path: qualcomm.com!usenet
From: [e-mail] (Nasser Abbasi)
Newsgroups: comp.lang.ada,comp.lang.c,comp.lang.c++
Subject: programming in the large. C++ vs Ada . was: Re: C/C++ knocks the crap out of Ada
Date: 7 Feb 1996 10:37:31 GMT
Organization: QUALCOMM
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JRFisher ([e-mail]) wrote:
> :...
> : Truth is, Ada has its strengths and is (for certain projects)
> : far superior to any other structured language. Ada is particularly
> : good for large-scale development because a few systems engineers can

Elliot replied:

> Setting responsibility interfaces is also the correct way for large, or
> complex projects using C++.  It is also easy to specify such interfaces
> using C++.


I think some of the language experts out there need to summarize to us
why Ada is considered better for large projects than C++.

It seems to me the most important part to have a language
considered suitable for large applications is the ability to
separate the interface from the implementation and things like
separate compilation. and to a lesser extent the ability
to do code reuse through taking advantage of inheritance
(i.e. child classes can share code from common parent  class as an
example) or though use of generic packages or templates.


It seems to me that both Ada and C++ both do the above, so
why exactly is it that Ada is considered to be better than
C++ for large applications?

Ada provides public interface that clients can build against, even
before the implementation (body) part of the package of the
interface is available.

Also in C++, clients can #include the .h file for the class they
wish to interface to, clients can look at the public part of the
class to see what the interface looks like, and code against that
(offcourse they can also  see the private part but if one can use
access that part of the class (legally), no harm is done!

Ada does strong type checking to make sure the client call is
consistent with what the package public interface is declared as.
In C++, it also does type checking (I guess somewhat less strongly
than Ada, because the primitives data types in C/C++ (short,long,char
etc..) are all implicitly interchangeable with each others), and
because it seems one can cast anything to anything, but still,
C++ does do good type checking.

Ada supports separate compilation, it also support child packages which
is nice feature to allow one to expand a package without having those
using the parent package to recompile if they do not use the new child
package (I think that how  I understand it to work).

In C++, It also support separate compilation. in C++, there is no such
thing as a package. in C++ the class is the master of everything,
In Ada, the package is, and the tagged types (i.e. the C++ equivalent
to  class) lives inside the package. So, Ada has one higher construct
which  is a package, but I am not sure how that makes Ada more suitable
for very large applications...

I think a nice thing would be to make a table listing the attributes
that are considered important for programming in the large, and give a
grade to each language in that department (may be a weighted grade
depending how important that attribute is), and add the score at the end,
and see who wins :)

I know this must have been talked about before, and there is I am sure
papers written about programming in the large, but I was interested to
know more about the differences in Ada and C++ in this aspect.


thanks
Nasser