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From: tmoran@acm.org
Newsgroups: comp.lang.ada
Subject: Re: discriminant in constraint must appear alone
References: <vspv69c17kr14c@corp.supernews.com>
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Xref: archiver1.google.com comp.lang.ada:3078
Date: 2003-12-02T21:15:36+00:00
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> > 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;
> >Are there other possiblities?

>    type R (D1, D2 : Positive) is new Ada.Finalization.Controlled with

  If you use Controlled, then this could be one of those occasions where
access types are really useful.

  type String_Ptr_Type is access String;
  procedure Free is new Ada.Unchecked_Conversion(String, String_Ptr_Type);
  type R (D : Positive) is
     record
        A : String_Ptr_Type;
        B : String_Ptr_Type;
     end record;

Then "R.A" needs to be "R.A.all", but R.A(i) can stay untouched.

   procedure Initialize (Obj : in out R) is
   begin
     A := new String(1 .. Obj.D);
     B := new String(1 .. Obj.D/2);
   end Initialize;
   procedure Finalize (Obj : in out R) is
   begin
     Free(Obj.B);
     Free(Obj.A);
   end Finalize;