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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: Possible Ada deficiency?
Date: 11 Jan 2005 16:08:37 -0500
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Date: 2005-01-11T16:08:37-05:00
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danmcleran@hotmail.com writes:

> >I've no idea what you're replying to here,
> 
> What I'm replying to is the argument that additional visibility
> restrictions aren't warranted because anyone can change the code to
> change the visibility. That seems like a pretty silly argument. If one
> takes this to the logical extreme, what's the point of having any
> information hiding capabilities at all? Couldn't someone always just
> change the code and change the visibility? Of course they could.

OK, I agree with that.  I certainly don't advocate eliminating the
visibility rules.

> >but note that the point of
> >the visibility rules is documentation
> 
> I don't buy this at all. I don't believe that the sole reason for
> visibility rules is documentation. There's obviously an intent to
> provide some information hiding and separation of interface from
> implementation.

I agree, but I call that documentation.  All this good info hiding and
whatnot doesn't affect the input/output behavior of the program.  But it
does document the logical structure of the program (such as which parts
of the code can meddle with which variables).  And (as you pointed out
in another note), the advantage of *this* kind of documentation (over
comments) is that it is trustworthy, whereas comments can and often do
contain misinformation.

- Bob