Re: Another important feature of Ada

[Brian Rogoff <bpr@shell5.ba.best.com>]

On Wed, 15 Nov 2000 mjsilva@my-deja.com wrote:
> In article <3A12041B.BCFD8CA0@worldnet.att.net>,
>   James Rogers <jimmaureenrogers@worldnet.att.net> wrote:
> > I have been following a thread between comp.lang.eiffel and
> > comp.lang.c++.moderated. The thread is boiling down to a discussion of
> > the virtues and vices of separating interface from implementation.
> >
> > The points being made against sepration of interface and
> implementation
> > focus on a concept that duplication of code is BAD, and separation
> > of interface and implementation requires some duplication of code.
> 
> I wonder how it could be otherwise?

In Ocaml, the interface file contains ony the type signature of functions
in the implementation file, and there is no need to repeat the type
information again in the implementation file. So admittedly there is some 
duplication (the name of a function) but much less than in Ada. There is 
actually no need to right a .mli file (equivalent to a .ads in GNAT) for 
each .ml (= .adb) unless you want to restrict what is visible or provide 
the ability for others to compile without the full implementation. 

However, this duplication has never been a significant issue for me in
Ada, or even C (my C code is very Ada-like) so I often wonder why people 
whine about this so much. I did a bit of programming in Sather and Eiffel
a while ago and I have to admit that while there are lots of nice features
in those languages I prefer Ada, and this separation, redundancy and all, 
plays a large part in that preference. 

-- Brian