Re: limited /non-limited tagged type

[Edward Fish <edward.r.fish@gmail.com>]

On Mar 4, 11:56 am, Hacid <chadi.alku...@gmail.com> wrote:
> Hi,
>
> I haven't found an existing topic about this, so I ask my question :
>
> I develop a package for colleagues. In this package I define a tagged
> type. I want to prevent them from doing assignments on this type. But
> I want to be able to do these assignments in my body.
>
> I understand why I can't define my type limited in the public part and
> not limited in the private part. But is there a way to do what I
> want ?
>
> Something like :
>
> package Foo is
>
>    type Object is tagged private;
>
>    function ":=" (Left : out Object,; Right : in Object) is abstract;
> -- I know this looks strange
>
> end Foo;
>
> Thanks.

Yes, I think.
You could add in an 'indirection step'.

Package Whatever is
Type Public_Type is limited private tagged;
--primitive functions.

Private
  - Base is the type that you will manipulate in the Body.
  Type Base is tagged record
    -- fields
Null;
   End Record;

Type Public_Type is Base with null record;

End Whatever;