Re: abstract sub programs overriding

["Robert I. Eachus" <rieachus@comcast.net>]

Hyman Rosen wrote:

> I think I still don't understand. If you say 'a := b;' and a has a
> Controlled type, isn't Finalize called on a before its bits are
> clobbered? So in your Initilaize example, when you say
> 'Object := (Parent_Type with ...);', isn't Finalize called on Object
> before its bits are replaced with the extension aggregate? And since
> we're in the first Initialize of Object, doesn't that mean that Finalize
> will be called on it before its first Initialize is complete?

Interesting thought.  RM 7.6 (17, 17.1, and 21) permit an implementation 
to omit that Finalization, and requires that it be omitted in some 
cases.  But you are right that a compiler could actually do that call in 
some circumstances.

You could write up an example and sent it to Ada Comment.  I can't 
imagine it being treated as high priority unless there are compilers 
that actually do the finalization.  Dimitry's two-stage initialization 
should mean that the unnecessary Finalize call is harmless, but there 
should probably be an AI to allow/require compilers to omit it in all 
cases.  (The problem as I see it is that Initialize should really have 
an out parameter instead of an in out parameter.)


-- 
                                           Robert I. Eachus

"The only thing necessary for the triumph of evil is for good men to do 
nothing." --Edmund Burke