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From: Georg Bauhaus <sb463ba@d2-hrz.uni-duisburg.de>
Newsgroups: comp.lang.ada
Subject: Re: Imitation is the sincerest form of flattery
Date: Fri, 21 Mar 2003 21:07:48 +0000 (UTC)
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Date: 2003-03-21T21:07:48+00:00
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Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> wrote:
:>package P is
:>
:>   type Unbounded_String (<>) is private;
:>
:>private
:>
:>   type Unbounded_String is
:>     array (Positive range <>) of Character;
:>
:>end P;
: 
: This would be a private type implemented by an array, but not an array
: implemented by some other type.

Where will this leed coders and readers? If I understand correctly,
what you want is an option to have objects with array access (attributes
etc.) that need not be arrays, privately. The same for other "ADTs"
that are provided by the language. That is, an option to override the
compilers regular job?

I'd prefer considering a rule that said, 'No arrays at all, please,
in specs!' :-)

In Eiffel, the basic types can be extended, and you can have
a sparse matrix derived from an ARRAY2, if you want to provide
your own implementation details, I think.

If, for a moment, you do not insist on arrays being suitable ADTs
for public access in specs, you can do that in Ada too, of course.
(With tagged types or with formal generics describing the "array like"
interface, which is not possible in Eiffel other than using FUNCTION
types(?), afaics.)