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From: "Baugereau" <baugereau@ifrance.kom>
Newsgroups: comp.lang.ada
Subject: Re: Specialization
Date: Thu, 30 May 2002 19:29:53 +0200
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> "Baugereau" <baugereau@ifrance.kom> wrote in message
news:<ad56du$pp4$1@wanadoo.fr>...
> > For instance, when I empty the container, I want to Finalize all the
> > elements if they are Controlled, and do nothing if not.
>
> Why wouldn't that happen automaticly? If you want to *manually*
> control finalization, you probably shouldn't be using controlled
> types.

I have this interface in my package (I snipped)


with Ada.Finalization;
use Ada.Finalization;
generic
type ELEMENT is private;
package Vector is
Default_Reserved : constant NATURAL := 32;
Growth : constant NATURAL := 32;
type ELEMENTPTR is access all ELEMENT;
type ELEMENTS is array(NATURAL range <>) of aliased ELEMENT;
type ELEMENTSPTR is access ELEMENTS;
type VECTOR is new CONTROLLED with record
   Size : NATURAL;
   Reserved : NATURAL;
   Data : ELEMENTSPTR;
end record;

-- Controlled type
procedure Initialize (obj : in out VECTOR);
procedure Finalize (obj : in out VECTOR);
procedure Adjust (obj : in out VECTOR);

-- Custom
function Get (obj : in VECTOR; index : in NATURAL) return ELEMENTPTR;
function Get (obj : in VECTOR; index : in NATURAL) return ELEMENT;
procedure Push_Back (obj : in out VECTOR; elt : in ELEMENT);
procedure Empty (obj : in out VECTOR);
procedure Erase (obj : in out VECTOR; first : in NATURAL; last : in
NATURAL);
private
procedure Realloc (obj : in out VECTOR; new_reserved : in POSITIVE);
end Vector;


the goal is to have Data as a raw storage of ELEMENTs that I can extend when
I Push_Back elements in the VECTOR...
Data has Reserved elements but only Size elements are meaningful.
And if I push_back a lot of elements, I don't want to realloc the storage
each time, so I make it grow linearly (for now).

Then when I erase, reserved must stay the same, size should become 0, and
objects in the storage should be finalized if they are not trivial.
Is it clear this time? Sorry I'm not a native speaker :)

Is this inherently flawed?
Should I not bother with growing Data by myself? I don't think so, because I
think "new" is costly (it is just a belief :) )