Information hiding (was Re: An observation of Ada ...)

[Robb.Nebbe@di.epfl.ch (Robb Nebbe)]

In article ,  writes:
|> Robb Nebbe says that hiding is all or nothing. That seems quite wrong. 
|> That's like saying a fence in real life is either not there or is 
|> impregnable.

Actually it would be more like saying you are either on one side of
the fence or the other.

|> A hidden interface in a language environment is exactly analogous to the
|> fence. But any fence can be knocked down if you have a bulldozer.

You don't so much knock the fence down as move things from one side
of the fence to the other. The ability to change from one side to
the other or to change which side of the fence something else is on
doesn't really change anything. You can still put everything in one
of two categories: those on the same side of the fence as you and
everything else. I.e. those that are hidden and those that are not.

I didn't mean to imply that there was anything permanent about a
certain object's status. It may very well be hidden in one context
and visible in another.

Robb Nebbe