Re: use of 'Base to compensate for the lack of information

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

On 2017-12-27 13:29, Mehdi Saada wrote:

> It seems good and practical, but at one time, I need the coefficient 
> to be multiplied by the coefficients' array index, which is a
> Natural.

Does not make sense, but ...

> So, I wrote
>      with function "*" (E1: in ELEMENT; E2: in NATURAL'Base) return ELEMENT is <>;
> 
> But since X'Base meant the unconstrained subtype of X, any type
> defined as "type T is range ..." won't fit in.

Since it is not Integer, yes.

> Yet I don't want any
> assumption on the nature of ELEMENT. It could be defined as Integer,
> Natural, modular types, or be rational made of modular types in case of
> FINITE FIELDS.

Array index of a rational type? That makes any array except empty and 
singleton countably infinite, well, well.

> How do I do while keeping that generic design ?

    type Index is range <>;
    with function "*" (Left : Element; Right : Index)
       return Element is <>;

  [ with function "*" (Left, Right : Element) return Element is <>; ]

If you want it be any copyable type, then

    type Bandersnatch is private;
    with function "*" (Left : Element; Right : Bandersnatch)
       return Element is <>;

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