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From: michael.jackson5@virgin.net (Mike)
Newsgroups: comp.lang.ada
Subject: Re: Invoking abstract subprograms in Ada95
Date: 22 Apr 2002 06:24:15 -0700
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"Grein, Christoph" <christoph.grein@eurocopter.com> wrote in message news:<mailman.1019449992.18314.comp.lang.ada@ada.eu.org>...
> The following compiles fine (with Rational Apex):
> 
> 
> package Abstract_Class_Wide is
> 
>     type T is abstract tagged null record;
> 
>     procedure P (X : T) is abstract;
> 
>     procedure C (X : T'Class);
> 
> end Abstract_Class_Wide;
> 
> 
> 
> package body Abstract_Class_Wide is
> 
>     procedure C (X : T'Class) is
>     begin
> 	P (X);
>     end C;
> 
> end Abstract_Class_Wide;

Hmm - the only differences I can see here are that my abstract method
also takes a classwide type, and is implemented in a child package.
Here's the distilled problem:

--
package abstract_bit is

type A is abstract tagged null record;

procedure generalOperation( this : in out A'class );
procedure specificOperation( this : in out A'class ) is abstract;

end abstract_bit;

--
package body abstract_bit is

procedure generalOperation( this : in out A'class ) is
begin
    specificOperation( this => this );
end generalOperation;

end abstract_bit;

--
package abstract_bit.concrete_bit is

type C is new A with null record;

procedure specificOperation( this : in out C );

end abstract_bit.concrete_bit;


--
package body abstract_bit.concrete_bit is

procedure specificOperation( this : in out C ) is
begin
    null;
end specificOperation;

end abstract_bit.concrete_bit;

-- main program
with abstract_bit.concrete_bit;

procedure annoying is

thingy : abstract_bit.concrete_bit.C;

begin
    abstract_bit.generalOperation( thingy );
end annoying;


Mike