Re: Self-referential 'Access

[matthew_heaney@acm.org (Matthew Heaney)]

In article <353B4DC4.EB3650F4@ghg.net>, Stanley Allen <sallen@ghg.net> wrote:

(start of quote)
------------ cellar.ads -----------
package Cellar is

    type Cell;

    type List is access all Cell;

    type Cell is limited record
        Contents : String (1 .. 10);
        Next_Cell : List := Cell'Access;  --line 9
        Prev_Cell : List := Cell'Access;  --line 10
    end record;

end Cellar;
-----------------------------------

Both compilers claim that the uses of the
'Access attribute are not valid because they
violate the rules concerning depth of
accessability.
(end of quote)

I don't know the exact rules here, but what I do in cases like this is just
use Unchecked_Access:

    type Cell is limited record
        Contents : String (1 .. 10);
        Next_Cell : List := Cell'Unchecked_Access;
        Prev_Cell : List := Cell'Unchecked_Access;
    end record;

This compiles cleanly using GNAT 3.10p.