Re: discriminant in constraint must appear alone

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

Thanks for your answers,

After evaluating the possibilities, I wil stick to:
    B : String (1 .. D);
and waist memory and having no constraint check. I am using it in a smal
program which I am writing. I can control my self in not violating the
constraints.

Giving the record two discreminants isn't nice for general use because
there needs to be a lot of comments describing the relation between the
discreminants. The type needs to be controled type to implement the
checking between the discreminants. The checking will be done at
run-time, not at compile-time.

Defining the type as a controlled type and using dynamic allocation for
the arrays is too mush overhead for my problem.

The best solution would be a change in the language. Is there something
foreseen for the new version of Ada?

Thanks,
Vincent Smeets


"Vincent Smeets" <No.Spam@T-Online.de> schrieb im Newsbeitrag
news:bqiq1m$uis$00$1@news.t-online.com...
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