Re: [boost] Report from Mont Tremblant C++ Committee meeting

From: Fernando Cacciola (fernando_cacciola_at_[hidden])
Date: 2005-10-14 08:32:29

Joel de Guzman wrote:
> Fernando Cacciola wrote:
>
>> It could help if you voiced your opinion on the problems posed by
>> your model (that is, that the effect of assignment would depend on
>> the lvalue being absent or not).  The only thing I heard from you on
>> this point since I raised it for the first time years ago was "it
>> doesn't look good, right". If this problem had not existed we
>> wouldn't be having this discussion. The only way out I see is to
>> figure out how to weight the problems and cons of each model. Simply
>> restating the cons of one of them isn't enough.
>
> Well, first of all, let me apologize for my tone and giving up too
> easily.

np

> FWIW, if I recall correctly what I said was more than
> "it doesn't look good", but I don't recall now.

I'm pretty sure just simply acknowldeged the problem but didn't propose an 
alternative solution.
I need to do it again but, in the past, I went over all of the related 
discussions twice.

> As far as I'm
> concerned, I always thought that what I was against was (and is)
> for special handling and special cases.

I'm against special cases too. But when the special handling is, or appears 
to be, necessary, getting rid of it is quite difficult.

> I've always stated that the tuple<T&> behavior should be the model 
> (actually, to be more
> basic: struct { T& x; } ).

I know, and I always counter-stated that it shouldn't.
Tuples can't be emptied. optional<> can; and in fact, nullability is it 
fundamental characteristic.
We can't model optional<> after something that doesn't do the very 
fundamental thing optional<> does.

> The nullability aspect is *besides*
> the point and has nothing at all to do with the rebinding semantics.

This is 100% false. Is 100% the opposite.

Rebinding semantics are there _precisely_ and _only_ to solve a problem 
posed by nullability.

Let me say that again:

Rebinding semantics are there _precisely_ and _only_ to solve a problem 
posed by nullability.

So once again, I ask you to deeply consider nullability and the problem it 
poses on assignment (I hope I don't have to repeat it again), then weight my 
proposed solution (rebinding) with your expectactions. If possible, propose 
a better solution or at least show that you don't think the problem is worth 
a controversial solution like rebinding.

Best

-- 
Fernando Cacciola
SciSoft
http://fcacciola.50webs.com/