Re: GNAT GPL 2013 bug?

[Shark8 <onewingedshark@gmail.com>]

On Friday, August 9, 2013 2:30:40 PM UTC-6, Adam Beneschan wrote:
> 
> It doesn't seem particularly useful to declare an untagged private type whose full type is something that only the package, or a child package, could derive types from.

I think I used this in one of my starts for a PostScript Interpreter. Postscript objects forming a hierarchy and all. So it could be useful if you are implementing something which has a common set of properties in implementation that are irrelevant to the actual client.

> Unfortunately, Ada doesn't have the concept of a "tagged type from which nothing can be derived".  That concept would be useful so that one could declare a type derived from Ada.Finalization.Controlled or some other tagged type, but declare that no other types may be derived from it, so that *new* operations declared for the type wouldn't have to be dispatching.

Good point; but on the flipside there's lots of workarounds for final objects in Java. So a choice either way has problems. IMO.