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From: "Ehud Lamm" <mslamm@mscc.huji.ac.il>
Newsgroups: comp.lang.ada
Subject: Re: List container strawman
Date: Thu, 8 Nov 2001 12:34:21 +0200
Organization: The Hebrew University of Jerusalem
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 <9rti6v$hcu$1@news.huji.ac.il> <WOzE7.10186$xS6.14012@www.newsranger.com>
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Date: 2001-11-08T12:34:21+02:00
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Ted Dennison <dennison@telepath.com> wrote in message
news:WOzE7.10186$xS6.14012@www.newsranger.com...
> In article <9rti6v$hcu$1@news.huji.ac.il>, Ehud Lamm says...
> >2. Why is List private? Shouldn't it be limited private, so we avoid
> >possible erros caused by aliasing?
>
> Ahh. It finally dawned on me what your objection to private was. (I'm a
little
> slow today again.) We are talking about what happens when you do a
> "List1 := List2;", aren't we?


Yep.

And to make things worse the scoping issues with Controlled are really
confusing for beginners.
Now I don't see any reason why newcomers shouldn't be able to reuse standard
containers, but I really don't want to start explaining "controled type must
be declared at library level".
Amusingly, a student just asked about this problem, in my course newsgroup,
trying to reuse a linked list package. They are now just learning about the
basics of ADTs, and Ada packages...

Are we coming to the conclusion that Ada95 approaches to memory management
(Controlled and storage pools), simply aren't enough for creating reliable
components, without imposing inessential restrictions?
We want user created abstractions to be as much like language supplied types
as possible, remember.

Ehud