Re: What is the point of Private?

["Ed Falis" <falis@verizon.net>]

On Thu, 28 Apr 2005 19:22:23 -0400, Simon Smith <Simon@skcs.co.uk> wrote:

>   however I dont really understand the point of it.
>
> Why is it there? I am sure I have heard talk that its to stop the client  
> from seeing exactly how the data is stored/manipulated however if people  
> really did want to know this wouldn't they just scroll down the ada spec  
> file and find out for themselves or am I missing something here?

The point is not to hide information from developers - it's to narrow the  
way that client code interacts with the services provided by a package, to  
provide interfaces that are straightforward to reason about.

An useful way to think about package specs is that the public part  
provides a logical interface representing the abstractions provided by the  
package, while the private part provides any additional relevant physical  
interface that the compiler might need.  (I believe this metaphor is from  
Tucker Taft).