Re: Record representation

[Mark H Johnson <mark_h_johnson@raytheon.com>]

Martin Dowie wrote:
> Is there anything that could be done (quickly ;-) by the ARG for Ada200Y to
> do something about this common pain in the *ss?
> 
> package Record_Rep is
> 
>    type A is record
>       I : Integer;
>    end record;
>    for A'Size use Integer'Size;
> 
>    type Index is new Integer range 1 .. 10;
> 
>    type AA is array (Index) of A;
>    for AA'Size use A'Size * Index'Last;  -- Not allowed!!!!!
> 
> end Record_Rep;
> 
> Surely the language could be made smart enough to support this? This can be
> a real maintenance nightmare to change.
> 

Let's generalize the situation slightly. What do you suggest be done if 
you change the data type from an Integer to a Natural? Using GNAT on 
x86's, Natural'Size is 31 (not 32) so that would imply setting AA'Size 
to 310 (and not 320) w/ a real pain in the *ss due to packing / 
unpacking of the data.

I remember a private email exchange with Robert Dewar about something 
similar to this a few years ago. Let me see if I can dig up the 
suggestions he had to improve the portability of your code.

   --Mark