Re: Ada design bug or GNAT bug?

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Tue, 23 Jun 2015 06:06:13 -0700 (PDT), vincent.diemunsch@gmail.com
wrote:

> I regard the refusal to create a "class type", like Ichbiah wanted it,
> just like we have a protected type and a task type, as the root of evil.

Ada's was is the only consistent way.

> For the OOP concept is based on an interface that is the same and
> instances that are different realizations of the same concept.

This is an inconsistent concept if taken literally. OOP never talk about
types being same. It does about same *behavior*. This is miles over miles
different. T and T'Class behave as if they were same in some contexts, but
they are not same from any point of view. Remember that class is a set of
types. A set is never equal to its instances. T'Class is a closure of
class. Closure of a set is not equal to an element of the set.

> One may think that the distinction between class type and tagged type is
> subtle, but the implications of it are huge : without class object one
> needs as replacement access to a class wide type.

Why?

(Access types appeared for having the Rosen's trick and working around
missing proper constructors and destructors.)

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de