Re: OO Style with Ada Containers

[braver <deliverable@gmail.com>]

On Nov 24, 1:46 am, Pascal Obry <pas...@obry.net> wrote:
> braver a écrit :
>
> > Very ineteresting -- Matt, can you pls elucidate these idioms below?
>
> > On Nov 19, 5:24 am, Matthew Heaney <matthewjhea...@earthlink.net>
> > wrote:
>
> >>    type Scanner (<>) is tagged limited private;
>
> > What does (<>) say here -- that the type is unconstrained?
>
> Yes. Scanner has a privately defined discriminant. So the public view of
> Scanner must be declared unconstrained.
>
> >> private
>
> >>    type Handle (S : not null access Scanner) is limited null record;
>
> >>    type Scanner (Last : Natural) is tagged limited record
> >>       H          : Handle (Scanner'Access);
> >>       Line       : String (1 .. Last);
> >>       Word_First : Positive;
> >>       Word_Last  : Natural;
> >>    end record;
>
> > What's the logic behind the definition and usage of the Handle H
> > throughout?
>
> It is for gaining write access to function in parameter. A simpler
> solution is:
>
>     type Scanner (Last : Natural) is tagged limited record
>        Self       : access Scanner := Scanner'Unchecked_Access;
>        Line       : String (1 .. Last);
>        Word_First : Positive;
>        Word_Last  : Natural;
>     end record;

Ah.  Didn't see H assigned -- in this case, Scanner'Access with the
type name means the address of the actual parent type record instance?

So basically to simplify even further, we'd just have procedures with
honest in out parameters?

Cheers,
Alexy