Re: Calling inherited primitive operations in Ada

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

On 2022-09-02 10:35, amo...@unizar.es wrote:
> On Thursday, September 1, 2022 at 11:33:47 PM UTC+2, Jeffrey R.Carter wrote:
>> On 2022-09-01 20:54, Emmanuel Briot wrote:
> 
>> As presented, this seems very over complicated. Elements and Definite_Elements
>> add no value, and this is just a complex way of writing
> 
> Going in a tangent, and I guess you know perfectly well, but this is caused by the painful duplication of code that Ada pushes you to by not having a native way to abstract storage of definite vs indefinite types. So the provider of a generic library very soon faces this conundrum about duplicating most interfaces, if not implementations, or resort to non-trivial generics, or accept an unnecessary penalty for definite types, or push to the client the definite storage matter. There's simply no satisfying solution here [that I know of]. The duplication of every standard container to have both [in]definite variants is a strong indictment.
> 
> I can understand the desire to have full control of allocation and object sizes, but that there's not a language way to work around this duplication, with appropriate restrictions to go with it, is... bothersome. Not making a dig at the ARG, which I understand is overstretched as it is.

Containers should be implementable without generics. Just saying.

> There was a proposal circulating some time ago that seemed promising, that I can't quickly find. Something like
> 
> type Blah is record
>      Dont_care_if_in_heap: new Whatever_Definiteness; -- Would apply to indefinite types or formals
> end record;

I would prefer constraint propagation/management support + tuples instead:

    type Blah (Parameters : Whatever_Definiteness'Constraints) is
       Sill_Care : Whatever_Definiteness (Parameters);
    end record;

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