Re: Possible Ada deficiency?

[Robert A Duff <bobduff@shell01.TheWorld.com>]

danmcleran@hotmail.com writes:

> Well, then why not make everything public and forget the whole idea of
> encapsulation altogether?

I've no idea what you're replying to here, but note that the point of
the visibility rules is documentation: you can tell, by reading the
code, which hunks of code can access which variables.  There is no
security goal here (i.e. prevent evil programmers from accessing
variables they shouldn't).

Why not go even further than your 'concealed' idea?  As in Eiffel, where
each class can name which other classes are allowed to meddle with
particular features of this class.

By the way, there's one question you haven't answered.  You desire to
prevent children from accessing parent-private stuff.  OK, that's a
legitimate concern.  But if you have a package X.Y that does not want to
access private-X stuff, then why do you want it to be a child in the
first place?

In my suggested solution, X could declare "I have no children", and then
Y would have to be *not* a child of X.  But obviously it doesn't *need*
to be a child of X, since it does not access private-X stuff.

Note that you can always declare an *empty* root package X, and have
children Y and Z that cannot access each other's private stuff.
And with my suggestion you could declare X.Y and/or X.Z to have no
children.  No children implies children cannot access private stuff!

- Bob