Re: Possible Ada deficiency?

[Nick Roberts <nick.roberts@acm.org>]

"Randy Brukardt" <randy@rrsoftware.com> wrote:

> The purpose of a child package is to extend its parent, often in ways not
> forseen by the parent's author. You're trying to prevent that purpose. If
> you don't want access to the private information, then don't write
> children. You have to at some point trust programmers to do something
> sensible; it's not the least bit hard to use 'Address or
> Unchecked_Conversion to access the private information of a package, no
> matter where you hide it.

I think you're missing the point a little, Randy.

Suppose there are some things in the private part of a package that you do
want private children of the package to be able to see (and modify), and
some other things in the private part that you do not want even private
children to be able to see (or modify).

In this case, it would seem it may be useful to have language construct that
allows this intention to be clearly stated, and enforced by the compiler.

If the intention later turns out to be an obstacle, the construct can be
changed or removed. But if the intention is /accidentally/ violated, it
could be very useful for the compiler to detect it and flag it up.

I suppose the problem is, such a construct would imply the need for a new
kind of private child -- perhaps a 'private private' child ;-) -- which
could access the secret stuff. And then one might have ultra-secret stuff,
and then ultra-secret children, and so on.

So possibly the argument against is that it would be overkill.

-- 
Best wishes,
Nick Roberts