Re: How to access an array using two different indexing schemes

[Jerry <list_email@icloud.com>]

On Wednesday, November 29, 2017 at 1:56:59 PM UTC-7, Randy Brukardt wrote:
> "AdaMagica"  wrote in message 
> > Am Mittwoch, 29. November 2017 17:03:04 UTC+1 schrieb Shark8:
> >
> >> Procedure Do_Stuffs( Data : in out General_Real_Array ) is
> >>   Subtype Indexing is General_Real_Array(1..Data'Length);
> >>   Subtype Offset   is General_Real_Array(0..Integer'Pred(Data'Length));
> >>
> >>   Indexed  : Indexing renames Data;
> >>   Offseted : Offset renames Data;
> >
> > No, that doesn't work! See previous posts.
> 
> Should have showed what does work:
> 
>   Indexed  : Indexing renames Indexing(Data);
>   Offseted : Offset renames Offset(Data);
> 
> The type conversions change the bounds as needed. Renames does not allocate 
> new memory.
> 
>                                      Randy.

Combining Shark8's plan with Randy's change and wrapping into a main program like this:

Procedure Shark8_And_Randy is
    Subtype Real is Float range Float'Range; -- Get rid of non-numeric.
    Type General_Real_Array is Array(Integer range <>) of Real;

    Procedure Do_Stuffs( Data : in out General_Real_Array ) is
        Subtype Indexing is General_Real_Array(1..Data'Length);
        Subtype Offset   is General_Real_Array(0..Integer'Pred(Data'Length));

        Indexed  : Indexing renames Indexing(Data);
        Offseted : Offset renames Offset(Data);
    Begin
        -- Stuffs!
        null;
    End Do_Stuffs;
Begin
    null;
End Shark8_And_Randy;

Results in GNAT complaining as such:

 shark8_and_randy.adb:9:37: renaming of conversion only allowed for tagged types
shark8_and_randy.adb:10:35: renaming of conversion only allowed for tagged types