Re: Extending a third party tagged type while adding finalization

[AdaMagica <christ-usch.grein@t-online.de>]

Am Sonntag, 3. Dezember 2017 10:29:07 UTC+1 schrieb Dmitry A. Kazakov:
Didn't try to compile but can't be legal. Nonabstract type has abstract primitive operation. not null anonymous access type has nothing assigned.

>     type T is new Ada.Finalization.Controlled with record
>        Self : not null access T'Class;
>     end record;
>     procedure Initialize (X : in out T);
>     procedure Foo (X : in out T) is abstract;
> 
>     type S is new T with ...
>     overriding procedure Foo (X : in out S);
> 
>     procedure Initialize (X : in out T) is
>     begin
>        X.Self.Foo; -- Boom!
>     end Initialize;
> 
> Dispatching calls must be illegal during type-specific 
> initialization/finalization. They are OK after these in the class-wide 
> initialization or before in the class-wide finalization.
> 
> > I was just musing about whether there was a different way
> > to do it.
> 
> Yes, there is no need to keep lists of objects. It is enough to have 
> only static analysis to decide what kind of finalization to call. Nobody 
> cares about finalization of implicitly collected objects, it is a bug 
> anyway.
> 
> > The Ada Finalization method is very clunky and can be
> > limiting at times.  There may not be a better way to do it.  At the
> > end of the day, I find a lot of the errors our programmers make is
> > forgetting to put in a Create/Intialize or Clean_Up/Finalize call
> > on objects that do not have Controlled ancestors.  It's a
> > maintenance headache, so I look for ways to try to remedy that via
> > design.
> 
> Welcome in the club.
> 
> -- 
> Regards,
> Dmitry A. Kazakov
> http://www.dmitry-kazakov.de