Re: Bus error

[Maciej Sobczak <see.my.homepage@gmail.com>]

On 28 Cze, 23:19, Robert A Duff <bobd...@shell01.TheWorld.com> wrote:

> >> No.  You can have an untagged private type whose full type is tagged.
>
> > You mean - untagged *public*, I suppose?
>
> Yeah, the terminology is confusing.

Yes, I meant "untagged public view". If any such thing exists. :-)

> I mean:
>
>     package P is
>         type T is limited private;
>     private
>         type T is tagged limited ...;
>     end P;
>
> or:
>
>     with Ada.Finalization; use Ada;
>     package P is
>         type T is limited private;
>     private
>         type T is new Finalization.Limited_Controlled with ...;
>     end P;

Yes, or even stricter:

    with Ada.Finalization; use Ada;
    package P is
        type T (<>) is limited private;
    private
        type T is new Finalization.Limited_Controlled with ...;
    end P;

which prevents uninitialized objects.

> Most AdaCore folks do not read comp.lang.ada at all.

Interesting.
Do they have so many official user complaints to read that they don't
have any time left? :-)

Hey, I can afford this joke, if they don't read it, right?

> And AdaCore certainly does not go looking for GNAT bugs on
> comp.lang.ada.  If you want a bug fixed, you have to send
> an official bug report.  And if you want it fixed fast,
> or want AdaCore to answer your questions, you have to spend
> money.

This is short-sighted. What if I'm not *yet* an Ada user, but just
contemplate this possibility and take into account *everything*,
including the consistency of Ada community?
By neglecting c.l.a. they're risking to lose a potential customer(s).

> > I consider this feature (limited
> > controlled with unknown discriminant) to be fundamental for correct
> > handling of external resources and other "interesting" types. It is
> > really a high time for this feature to get a wider adoption.
>
> Right, but it's the Ada 2005 build-in-place function return stuff that
> makes these really useful.

Yes. Interestingly, it works fine with my compiler. I just consider
the aggregate to be more concise in simpler cases.

>  The bug we're talking about (assuming it
> really is the same bug that I fixed, which I can't promise) was a
> nasty interaction between build-in-place functions and controlled
> types.

Controlled types are messy.

--
Maciej Sobczak
http://www.msobczak.com/