Re: Musing on defining attributes and the ability to define an "abstract type X"-interface.

[Shark8 <onewingedshark@gmail.com>]

On Saturday, August 5, 2017 at 11:18:44 AM UTC-6, Dmitry A. Kazakov wrote:
> On 2017-08-05 18:51, Shark8 wrote:
> 
> > This is about having an "abstract type", it's about getting at the
> > underlying interface (general-sense, not OOP-sense)
> First, it is the same sense.  Second, Ada has abstract types (ADT is Ada 85).

Why do you assert this?
It's demonstrably not the case that it's OOP because, as you point out, Ada 83 had the concepts w/o being an OOP language.

As to the second point, ADT is Abstract Data Type -- we're obviously *NOT* talking about data here so it doesn't apply... and even if it did, you *still* would have to illustrate how and ADT provides the sort of access/uniformity of interface being talked about.

> The point is having hierarchies of types = classes.
> 
> - Ada 85 had built-in classes.
> - Ada 95 added classes of tagged types with representations built by - 
> record extension.
> - Ada 2005 added classes of siblings sharing null representation (Ada 
> interfaces).

And this proposal is about adding the ability to extend to the whole language without having to depend on (or be restricted to) tagged types.

> 
> There is a whole world beyond these.

Even within the Ada language there's more here.