discriminant in constraint must appear alone

["Vincent Smeets" <No.Spam@T-Online.de>]

Hallo,

I want to define a discriminated record type with two arrays. One array only half the size of the other. Below is the type definition that I want to use.

   type R (D : Positive) is
      record
         A : String (1 .. D);
         B : String (1 .. D / 2);
      end record;

This type definition can't be compiled by the GNAT compiler. It gives the error message
    "discriminant in constraint must appear alone"
for the record component B. I know this isn't correct Ada, but how should I define the type in a correct way?

I have defined B as
    B : String (1 .. D);
and only used the first half of it, but this way I waist memory and can't have any Ada constraint checks for component B. So this is not the way I want to do it.

Are there other possiblities?


-- 
Thanks,
Vincent Smeets