[boost] Re: Perfect Forwarding (almost)

From: Rani Sharoni (rani_sharoni_at_[hidden])
Date: 2004-02-11 09:20:11

David Abrahams wrote:
> "Rani Sharoni" <rani_sharoni_at_[hidden]> writes:
>
>>>> When source and destinations un-cv types are the same or
>>>> base/derived direct initialization and copy initialization are the
>>>> same (per 8.5/14/4/2) and this fact was (viciously) exploited by
>>>> the old auto_ptr.
>>>
>>> Something's missing from that sentence to make it comprehensible.
>>>
>>> It has the same grammatical structure as "When my hand is blue or my
>>> hair is green and I was a fool", which is not a complete sentence.
>>
>> I'm not sure that I understand your intention.
>
> I'm trying to say that I don't understand what you're saying in that
> "sentence", and I'm trying to explain why I don't understand it.  The
> "sentence" is grammatically incomplete.  I'd like you to explain what
> you're trying to say.

For some reason I thought that what I wrote is so trivial that even grammar
errors will not hide my intentions. It seems that Christoph Ludwig
understand my intentions.

Direct initialization is the *same* as copy initialization when constructing
object of the same type using non-explicit (i.e. converting) constructor.

struct A { A(int); };

A a1(A(10));  // #1
A a2 = A(20); // #2 same as #1

Both initializations are the same per 8.5/14/4/2:
<Q> If the initialization is direct-initialization, or if it is
copy-initialization where the cv-unqualified version of the source type is
the same class as, or a derived class of, the class of the destination,
constructors are considered. The applicable constructors are enumerated
(13.3.1.3), and the best one is chosen through overload resolution (13.3).
</Q>

IMO your suggestion is fully compliant and EDG has bug that confuses
everyone.

I don't have anything else to add to this discussion.

Thanks,
Rani

No alarms and not surprises silence.