Re: unconstrained subtype in component declaration, tagged OO

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Sat, 26 Mar 2011 13:24:37 -0700, Nasser M. Abbasi wrote:

> I am learning a bit about Ada OO, and I have simple problem,
> hopefully with simple answer, but not able to find one so far.
> 
> I want to make an object, but the declaration of the tagged record
> would include an array in it. The size of this array, at the
> time of declaration is not know. But will be when the
> object is created.
> 
> So, what is the correct way to declare such an object?
> 
> Here is my ads package for the object:
> 
> -------------------foo.ads-------
> package foo is
>     type foo_t is tagged private;

   type foo_t (<>) is tagged private;

>     -- primitive operations
>     function make(n:natural) return foo_t;
> private
>      type u_t is array(natural range<>) of float;
> 
>      type foo_t is tagged record
>           u : u_t:= (others=>0.0);  -- problem here
>      end record;

   type foo_t (Length : Natural) is tagged record
      u : u_t (1..Length) := (others=>0.0);
   end record;


   function make(n:natural) return foo_t is
   begin
      return (n, (others => 0.0));
   end make;

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de