Re: Ada 95 and Class attribute for none-tagged incomplete type

["Randy Brukardt" <randy@rrsoftware.com>]

"Robert A Duff" <bobduff@shell01.TheWorld.com> wrote in message 
news:wcc3a7uusn8.fsf@shell01.TheWorld.com...
> "Randy Brukardt" <randy@rrsoftware.com> writes:
>
>>...All this special rule eliminates is the need to declare
>> an incomplete type in this one unusual case (the private type in cases 
>> like
>> this is best declared as tagged, so this shouldn't happen very often). 
>> Seems
>> like a pile of work for an implementation and for the language just to
>> eliminate one line in a private part.
>
> The problem is that declaring that incomplete type is illegal.
> Eliminating the need for one _illegal_ line isn't such a bad thing.  ;-)

Why is it illegal? Doesn't seem like it ought to be on the face of it.

...

> We could have made it legal, I suppose.  But having three views of a
> type might make more trouble for the compiler than the existing
> rules.

Apparently, you haven't thought to hard about the semantics of limited 
views. :-) *Every* private type that can be used in a limited view has (at 
least) three views (the incomplete view from the limited view being the 
third).

I believe we (Tucker and I? On the ARG list? I don't remember) were 
discussing eliminating some of the restrictions on the declaration and 
completion of incomplete types in order to make the use of "incomplete 
instances" or "intgregated packages" or whatever we end up with more useful. 
(Many of the "derivation" problems go away if you can simply declare an 
incomplete type ahead of time to introduce the proper name for the type.)

                            Randy.