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From: Natasha Kerensikova <lithiumcat@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: S-expression I/O in Ada
Date: Sun, 22 Aug 2010 10:21:08 +0000 (UTC)
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Date: 2010-08-22T10:21:08+00:00
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On 2010-08-20, Yannick Duchêne <yannick_duchene@yahoo.fr> wrote:
> Depends if it has a default discriminant or not. If it has, and you  
> declare an object of such a discriminated type somewhere, without  
> initialization, you will got nearly the same, except that in Ada you will  
> not be allowed to change arbitrary members without regards to the actual  
> discriminant. If you want to change it, you will have to assign the object  
> as a whole, to give both the new discriminant and the value of the members  
> which will comes into live with it.

This is very interesting, it will help when I write the parser (with
per-state context information).

But then it means the following type allow some sort of dynamic array?

type Dynamic_Whatever_Array (Size : Natural := 0) is
   array (1 .. Size) of Whatever;


Then is there a simpler way to replace the object than :

procedure Foo is
   object : Dynamic_Whatever_Array;
   Computed_Size : Natural;
begin
   ...
   Computed_Size := ...;
   ...

   declare
      new_object : Dynamic_Whatever_Array(Computed_Size);
   begin
      -- initialize new_object contents
      object := new_object;
   end;

   ...
end Foo;


Or is it complete nonsense?


Thanks for your help,
Natacha