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From: "Martin Dowie" <martin.dowie@baesystems.com>
Newsgroups: comp.lang.ada
Subject: Re: Ada & Postgresql
Date: Mon, 6 Sep 2004 13:54:04 +0100
Organization: BAE SYSTEMS
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Date: 2004-09-06T13:54:04+01:00
List-Id: <comp.lang.ada>

Marius Amado Alves wrote:
>> ...I can't pinpoint now what annoying Ada 95 feature
>> I was escaping back in 2001 when I wrote this package and its
>> applications. Never mind. Just write Pgsql_Controlled.
>
> OK, I just took the time to write this. While I'm at it, I'll control
> also Db_Type, to call Close on finalization. Oops, no, Ada 95 does not
> let me do that, it makes
>
>     function Execute (Db: Db_Type; Command: String) return
> Result_Type;
>
> illegal, because an "operation can be dispatching in only one type."
>
> This is one of many examples of what I call "Ada getting in the way."

But isn't the solution to this to just wrap one of them in a 'plain' record,
e.g.

package Foo is
   type Command_Type is private;
   type Result_Type is private;
   -- whatever
   function Bar (CT : Command_Type) return Result_Type;
private
   type Command_Type is new Ada.Controlled...
   procedure Finalize (C : in out Command_Type);

   type Inner_Result_Type is new Ada.Controlled...
   procedure Finalize (IR : in out Inner_Result_Type);

   type Result_Type is record
      IR : Inner_Result_Type;
   end record;
end Foo;

Cheers

-- Martin