Re: Q: Endless loop by dispatching

[Dmitry A. Kazakov <mailbox@dmitry-kazakov.de>]

On Sat, 19 Jul 2003 05:48:23 GMT, "Robert I. Eachus"
<rieachus@attbi.com> wrote:

>1) All objects of a type derived from Ada.Finalization.Controlled by 
>default call the same version of Initialize?

Which one version? How a public part might know that there is a
privately declared Initialize?

>or
>
>2) Information hiding in effect AT THE PLACE OF THE CALL can determine 
>which version of a subprogram is called?

For good or bad, but this was the intention, i.e. to hide Initialize
and here you are.

>If you vote for 2), I won't argue, I'll take it as data.  The important 
>part for the ARG is that in this (foot shooting) case we have to choose. 
>  The two alternatives are clearly incompatible, and that is what the 
>program was written to demostrate.

IMO the problem is that you can have both an overloading in the public
part and an overriding in the private. This is a nasty problem,
because:

1<-->A. if we prohibit this, we would expose something from the
private part;

2<-->B. if we accept this, we have pitfalls as your example shows.

I think that the syntax should clearly distinguish declaring a
primitive (and thus overriding) vs. non-primitive (overloading)
subprogram. Further, no matter how painful it could be, one should
probably outlaw non-primitive subprograms with tagged non-class-wide
arguments. This again would solve little as long as a type can be
publicly non-tagged, being tagged privately. So again I have to repeat
the same old slogan: ALL TYPES BE TAGGED!

---
Regards,
Dmitry Kazakov
www.dmitry-kazakov.de