Re: Variant record limitation - what's a better solution?

[Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org>]

On 07/03/2013 12:52 AM, Peter Brooks wrote:
>
> type
> my_object(X : size_type) is
>         record
>                name : string(1..80);
>                case X is
>                   when small => Y : small_type; -- line 20
>                   when medium => Y : medium_type; -- line 21
>                   when large => Y: large_type; -- line 22
>                end case;
>         end record;
>
> The errors are:
> line 21  'Y' conflicts with declaration at line 20
> line 22 'Y' conflicts with declaration at line 21
>
> I was hoping to have a different type depending on the case, but this doesn't seem allowed. What would achieve this?

The problem isn't the types but the component identifiers. Each component name 
must be unique, even across different variants. So you could do something like

type My_Object (Size : Size_ID) is record
    Name : String (1 .. 80);

    case Size is
    when Small =>
       Y_Small : Small_Value;
    when Medium =>
       Y_Medium : Medium_Value;
    when Large =>
       Y_Large : Large_Value;
    end case;
end record;

-- 
Jeff Carter
"My brain hurts!"
Monty Python's Flying Circus
21