220 4729 <51A670DC.2010102@wanadoo.fr> article Path: news.gmane.org!not-for-mail From: "Vicente J. Botet Escriba" Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Remove vector? Date: Wed, 29 May 2013 23:19:24 +0200 Lines: 215 Approved: news@gmane.org Message-ID: <51A670DC.2010102@wanadoo.fr> References:

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[80.12.242.128]) by mx.google.com with ESMTP id v8si23051291eeg.185.2013.05.29.14.19.25 for ; Wed, 29 May 2013 14:19:25 -0700 (PDT) Received-SPF: neutral (google.com: 80.12.242.128 is neither permitted nor denied by best guess record for domain of vicente.botet@wanadoo.fr) client-ip=80.12.242.128; Original-Received: from pc4.home ([2.11.193.225]) by mwinf5d29 with ME id hxKQ1l00H4sEqES03xKQGi; Wed, 29 May 2013 23:19:25 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:17.0) Gecko/20130509 Thunderbird/17.0.6 In-Reply-To: X-Original-Sender: vicente.botet@wanadoo.fr X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 80.12.242.128 is neither permitted nor denied by best guess record for domain of vicente.botet@wanadoo.fr) smtp.mail=vicente.botet@wanadoo.fr Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:4729 Archived-At: This is a multi-part message in MIME format. --------------030901000709050908050009 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Le 29/05/13 19:37, Nevin Liber a =E9crit : > On 29 May 2013 12:20, Vicente J. Botet Escriba=20 > > wrote: > > Le 28/05/13 22:12, Howard Hinnant a =E9crit : >> On May 28, 2013, at 4:00 PM, Nicol Bolas wrote: >> >>> Personally, I agree with Howard; we should add a class that has all= of this functionality (presumably with some degree of required sizing) tha= t would be a drop-in replacement for those who need the sizing features of = vector. But the question remains: even with a drop-in replacement, ho= w much code will be broken because of this? >> Model this after the auto_ptr -> unique_ptr transition: >> >> Step 1: Introduce bit_vector (or whatever) and deprecate the vector= specialization. /Somehow/ motivate people to migrate. > I think that we will need also to add a std::*new_*vector that > behaves like std::vector but doesn't have the bool > specialization and *deprecate* std::vector :-> > > > -100. > > * Annoying 99% of all C++ users is a horrible, horrible idea. Right. Forget the last sentence. > > * I'd hate to use a code base that had two different, unrelated types=20 > for doing the exact same thing, since ultimately these things end up=20 > interfaces. Actually, I already have that, as people are trying to=20 > migrate from Boost over to std (such as shared_ptr), and it is=20 > anything but easy (because we are dependent on libraries developed=20 > for/by other groups, and changing those interfaces is a scheduling=20 > nightmare). You are right. What we would need is 'single' type that behaves as the=20 current vector except for bool and that behaves as vector if=20 vector was not specialized. I don't know if we can specialize an alias=20 and if the following is correct template class new_vector { the same definition as vector now }; template alias vector=3D new_vector ; template < typename Allocator> class vector { the same definition as now } ; If this is correct, users of vector would get the same behavior. Users=20 of new_vector would get the behavior without the bool specialization. Any function expecting a vector work with new_vector except for=20 bool. The same is valid for function expecting new_vector you can use=20 it with vector except for bool. Of course we need a bit_vector class that replace the vector=20 specialization as Howard suggested. After the deprecation period, new_vector and vector would have the same=20 behavior and new_vector could be deprecated at his turn. Vicente --=20 ---=20 You received this message because you are subscribed to the Google Groups "= ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/?hl=3Den. --------------030901000709050908050009 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

Le 29/05/13 19:37, Nevin Liber a écrit :

On 29 May 2013 12:20, Vicente J. Botet Escriba <vicent= e.botet@wanadoo.fr> wrote:
Le 28/05/13 22:12, Howard Hinnant a écrit :
On May 28, 2013, at 4:00 PM, Nicol Bolas <jm=
ckesson@gmail.com> wrote:
Personally, I agree with Howard; we should add a cla=
ss that has all of this functionality (presumably with some degree of requi=
red sizing) that would be a drop-in replacement for those who need the sizi=
ng features of vector<bool>. But the question remains: even with a dr=
op-in replacement, how much code will be broken because of this?
Model this after the auto_ptr -> unique_ptr transit=
ion:

Step 1:  Introduce bit_vector (or whatever) and deprecate the vector<boo=
l> specialization.  /Somehow/ motivate people to migrate.
I think that we will need also to add a std::new_vector&= lt;T> that behaves like std::vector<T> but doesn't have the bool specialization and deprecate std::vector :->
-100.

* Annoying 99% of all C++ users is a horrible, horrible idea.

Right. Forget the last sentence.

* I'd hate to use a code base that had two different, unrelated types for doing the exact same thing, since ultimately these things end up interfaces. Actually, I already have that, as people are trying to migrate from Boost over to std (such as shared_ptr), and it is anything but easy (because we are dependent on libraries developed for/by other groups, and changing those interfaces is a scheduling nightmare).

You are right. What we would need is 'single' type that behaves as the current vector<T> except for bool and that behaves as vector<bool> if vector was not specialized. I don't know if we can specialize an alias and if the following is correct

template <typename T, typename Allocator>
class new_vector { the same definition as vector<T, Allocator> now };

template <typename T, typename Allocator>
alias vector=3D new_vector<T, Allocator> ;

template < typename Allocator>
class vector<bool, Allocator> { the same definition as now } ;
If this is correct, users of vector would get the same behavior. Users of new_vector would get the behavior without the bool specialization.
Any function expecting a vector<T> work with new_vector<T> except for bool. The same is valid for function expecting new_vector<T> you can use it with vector<T> except for bool.

Of course we need a bit_vector class that replace the vector<bool> specialization as Howard suggested.
After the deprecation period, new_vector and vector would have the same behavior and new_vector could be deprecated at his turn.

Vicente

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