Re: Type in allocator has deeper level than designated class-wide type

[Adrian Hoe <abyhoe@gmail.com>]

On Jun 14, 9:08 am, Adam Beneschan <a...@irvine.com> wrote:
> On Jun 13, 5:49 pm, Adrian Hoe <aby...@gmail.com> wrote:
>
>
>
>
>
> > On Jun 14, 1:11 am, Adam Beneschan <a...@irvine.com> wrote:
>
> > > On Jun 13, 8:31 am, Adrian Hoe <aby...@gmail.com> wrote:
>
> > > > Hi all,
>
> > > > I have stomped into above error and I am stuck with the error and
> > > > runtime exception PROGRAM_ERROR : accessibility check failed.
>
> > > > Here's the fragment of my codes:
>
> > > > generic
> > > >    N : Positive;
> > > >    type Item is private;
> > > > package High_Cloud is
>
> > > >    package List renames Heterogeneous_Doubly_Link_List;
> > > >    use List;
>
> > > >    type Data_Array               is array ( 1 .. N ) of Item;
>
> > > >    type Element_Record           is new List.Node with private;
> > > >    type Series_Access            is new List.Access_List;
>
> > > > private
>
> > > >    type Element_Record is new List.Node with
> > > >       record
> > > >          Name           : Unbounded_String;
> > > >          Color          : Unbounded_String;
> > > >          Data           : Data_Array;
> > > >       end record;
>
> > > > ...
> > > > end High_Cloud;
>
> > > > In the package body of High_Cloud, I have a procedure:
>
> > > >    procedure Add
> > > >       ( Cloud          : in out High_Cloud_Record;
> > > >         Name            : in     Unbounded_String;
> > > >         Color           : in     Unbounded_String;
> > > >         Data            : in     Data_Array )
> > > >    is
>
> > > >       New_Element : List.Access_Node;
>
> > > >    begin
>
> > > >       New_Element := new Element_Record'
> > > > <========== Error/Warning here.
> > > >                         ( Constructor.Init ( Name, Color, Data) ) ;
>
> > > >       Concatenate ( Cloud.Series, New_Element ) ;
>
> > > >    end Add;
>
> > > > My intention is to use genericity to create a data which is an array
> > > > (1..N) of any_type. This data is then stored in a list. Procedure Add
> > > > instantiate (by calling to Constructor.Init) the list's node with
> > > > data.
>
> > > > I have read the ARM 3.10.2 and 3.10.1 and also John Barnes book yet I
> > > > still have no clue how to solve the problem.
>
> > > > Can you please help? Thanks.
>
> > > I think we need to see the definition of Constructor.Init, at least.
> > > (I'm guessing that Heterogeneous_Doubly_Link_List is a library package
> > > that defines Node as a tagged record and Access_Node as "access all
> > > Node'Class".  But I don't have a guess about what Init is.)
>
> > >                                -- Adam
>
> > Yes, you are right. In Heterogeneous_Doubly_Link_List:
>
> >    type List        is limited private;
> >    type Access_List is access List;
>
> >    type Node           is tagged private;
> >    type Access_Node   is access all Node'Class;
>
> > private
>
> >    type Node is tagged record
> >       Previous : Access_Node;
> >       Next     : Access_Node;
> >    end record;
>
> >    type List is limited record
> >       Head    : Access_Node := null;
> >       Tail    : Access_Node := null;
> >       Current : Access_Node := null;
> >       Count   : Unsigned := 0;
> >    end record;
>
> > And:
>
> >    package body Constructor is
>
> >       function Init
> >          ( New_Name  : Unbounded_String;
> >            New_Color : Unbounded_String;
> >            New_Data  : Data_Array )
> >       return Element_Record is
> >       begin
> >          return ( List.Constructor.Init
> >                      with
> >                         Name  => New_Name,
> >                         Color => New_Color,
> >                         Data  => New_Data
> >                 ) ;
> >       end Init;
>
> >    end Constructor;
>
> > Is the problem lying in the Data : Data_Array in Element_Record or in
> > the return statement of Constructor.Init?
>
> Where is the above Constructor package defined?  Is it directly within
> High_Cloud, or is it defined inside a subprogram in the body of
> High_Cloud?
>
> Assuming it's the former, I can't get either our compiler or GNAT
> (4.5.2) to generate an error or warning message.  However, I don't
> know if any relevant rules about accessibility have changed in Ada
> 2012.  I'd have to study this one further.  If you're not using our
> compiler or GNAT, and it's an Ada 2005 compiler, it could well be an
> error in your compiler.
>
>                                -- Adam



Yes, it is directly within High_Cloud.

I am using GNATMAKE  4.4.0 20080314 on Mac OS X 10.5.8, Xcode 3.0.

--
Adrian Hoe
http://adrianhoe.com/adrianhoe