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From: Ludovic Brenta <ludovic@ludovic-brenta.org>
Newsgroups: comp.lang.ada
Subject: Re: Ada vs Eiffel - Ada programmer approach
Date: Tue, 26 May 2009 06:37:49 -0700 (PDT)
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Date: 2009-05-26T06:37:49-07:00
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Pascal Obry wrote on comp.lang.ada:
> Tomek Walkuski a =E9crit :
> > - what, in your opinion, is worse in Ada, in contrast to Eiffel?
>
> - memory management (not GC - I know that there is nothing in the
> standard that forbid it - and this would be certainly really handful for
> some domain)

I agree that it would be nice if some Ada compilers would provide an
optional garbage collector. One exists as a third-party add-on to GNAT
but I've never used it and it's not part of AdaCore's or the FSF's
distributions.

In fact, I would like it if the garbage collector could optionally log
all deallocations while the program runs, so I can find memory leaks,
correct them, and remove the garbage collector later :)

> - multiple inheritance

I'm not sure this is a good thing. In fact, I'm not sure simple
inheritance is always a good thing, either. I tend to prefer
composition and generics.

> - DbC with pre-condition/post-condition/invariant

When I read Bertrand Meyer's "Object-Oriented Software Construction",
I too thought that DbC was a brilliant idea. Now I'm less convinced. I
see two major drawbacks to DbC:

- pre/post conditions and invariants involve run-time checks most of
the time (if not all the time). They slow the program down if enabled,
or become useless when disabled for performance. I like static
checking much better; Ada provides a lot of that out of the box (much
more than Eiffel) and Spark goes way beyond even that.

- in most of the examples I saw in the literature, only very simple
subprograms would have a contract and the contract would mostly repeat
the body of the subprogram. This redundancy is counter-productive. For
more complex subprograms, it can be very difficult to write pre and
postconditions and invariants; Ada's pragma Assert provides what I
need in these (rare) cases  because I can put such pragmas in the
middle of a subprogram, for example.

--
Ludovic Brenta.