Re: how to force the Small aspect of a new type derived from the generic formal type ?

["Alejandro R. Mosteo" <alejandro@mosteo.com>]

On 25/01/18 13:54, Mehdi Saada wrote:
>> Either the teacher is asking for the impossible
> 
> Actually the teacher isn't asking to do that: he asked at some point to make it generic, at and at another, to force the Small. I assumed we could do both.
> 
>> you can't use most representation  aspects on a type derived from a generic formal type.
> 
> I understand. But with this statement:
>     type Modele is delta <>  with SMALL => MODELE'DELTA;
> I intend to pass a contract, so that only types whose Small is set the same as the Delta will be accepted as valid parameters. I SUPPOSED it works like this... I suppose now I was wrong ?
> 

Unfortunately aspects+generics (or, in general <advanced 
feature>+generics) is one of the points where Ada orthogonality breaks 
down. In exchange you get sane generics, when compared to macro templates.

I'm saying this in a practical, user-experience sense, not as a language 
lawyer (which I'm not).

You can somewhat mitigate this with generic package formals, or with the 
"type T is new Base with private" kind of formals.

Even after many years of using Ada, I find the table in the following 
link a lifesaver from time to time:

https://en.wikibooks.org/wiki/Ada_Programming/Generics#Generic_formal_types

Incidentally, I wonder what good Ada cheatsheets are out there.