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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Self pointer in limited record
Date: Fri, 7 Sep 2007 20:16:23 -0500
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Date: 2007-09-07T20:16:23-05:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message
news:9fy1xoukz1e3$.h574sqmiauri$.dlg@40tude.net...
> On Fri, 31 Aug 2007 16:47:29 -0000, amado.alves@gmail.com wrote:
>
> > Then you have seen illegal Ada code repeatedly. I wish this were
> > possible myself. Or more simply:
> >
> > type T is -- limited or not
> >    Self : access T := T'Unchecked_Access;
> >    ...
> > end;
>
> T cannot be non-limited, because otherwise passing it by copy would make
> rubbish out of Self. In any case it would make little sense if not access
> T'Class.

Sure it can, just not written this way. The original question used
Limited_Controlled, and thus you can initialize the pointer in the
Initialize routine:

    procedure Initialize (Obj : in out T) is
    begin
        Self := Obj'Unchecked_Access;
    end Initialize;

If the type is non-limited, you have to "fix" the self-pointer in Adjust.
That's essentially how Claw does it.

I personally prefer putting the code in Initialize (it's not so tricky that
way, and you have more flexibility), but YMMV.

                             Randy.