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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: abstract sub programs overriding
Date: Tue, 16 Mar 2004 17:14:45 -0600
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Date: 2004-03-16T17:14:45-06:00
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"Robert I. Eachus" <rieachus@comcast.net> wrote in message
news:N_ydnXrG6NPEtcrdRVn-hg@comcast.com...
> 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.

I don't see why you think that. 'Object' in this case is not a new object;
it is a parameter passed into Initialize, and the compiler certainly cannot
assume that it is uninitialized.  In any case, RM 7.6(21) is seriously
screwed up; AI-147 changes it quite a bit, mainly to eliminate bogus
'optimizations' like the one you seem to think is allowed here. (Eliminating
this Finalize call would make a library like Claw impossible to write,
because you could have objects that are never finalized and thus never
unhooked from the lists to which they belong.)

                Randy.