Re: Private primitive operations available to entire package hierarchy. Can it be done?

["Randy Brukardt" <randy@rrsoftware.com>]

"Lucretia" <lucretia9@lycos.co.uk> wrote in message
news:1123524248.690333.24270@g14g2000cwa.googlegroups.com...
> <quote>
> We do use something like reference counting to allow Window objects to
> be
> assigned. But that capability was a mistake - we wouldn't do it if
> starting
> over - so I won't try to describe it.
> </quote>
>
> I started with a non-limited hierarchy that could be copied but found
> that not all wxWidgets classes can be copied as the copy constructor is
> private in certain objects, e.g. all wxWindow derived types. So, I now
> have a limited hierarchy, even though certain objects need to be
> copiable, e.g. wxEvent derived types.

There are ways around that. But we ultimately found that they made it very
hard to cleanly add extension components to derived window classes. So many
of our programs include
    procedure Adjust (Object : in out Whatever_Window) is
    begin
          raise Program_Error;
    end Adjust;

Effectively making that type limited (without the compile-time checking).
But of course, if we were going to do that, we might as well have made the
types limited in the first place and avoided the complications. So I agree
with your intent to make them limited.

                        Randy.