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using boost::is_same with enums
by 乔志强 27 May '11

27 May '11

template <class T, class U> struct is_same : public true_type-or-false_type {}; 'boost::is_same' : invalid template argument for 'T', type expected is_same need type, not const value. You can use: BOOST_STATIC_ASSERT((P == eDivide && Q == eMinus) || (P == eMult && Q == ePlus)); > Message: 4 > Date: Fri, 27 May 2011 10:22:24 +0100 > From: przemyslaw.sliwa(a)uk.bnpparibas.com > To: boost-users(a)lists.boost.org > Subject: [Boost-users] using boost::is_same with enums > Message-ID: > <OF533BB172.765E47C7-ON8025789D.00332EF1-8025789D.00337D99@bnpparibas > .com> > > Content-Type: text/plain; charset="us-ascii" > > Hello, > > I am trying to use boost::is_same in the folloting case > > enum eOperation { ePlus = 0, eMinus, eMult, eDivide }; > > template<eOperation P, eOperation Q> > boost::shared_ptr<std::vector<intervalPtr> > convertIntervals() const > { > BOOST_STATIC_ASSERT( (boost::is_same<P, eDivide>::value && > boost::is_same<Q, eMinus>::value) || > (boost::is_same<P, eMult>::value > && boost::is_same<Q, ePlus>::value)); > > static const double dNoOfSecsInADay(3600*24); > boost::shared_ptr<std::vector<intervalPtr> > out(new > std::vector<intervalPtr>(m_intervals.size())); > > // more code here > > return out; > } > > Could someone help me with this? > it does not compile at all on VC++2010. The error i get is > > 1>Pshemek -> this needs to be improved, no constructor calls at all when > merged back to HEAD > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'T', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1> d:\dev\13_1x\development\cpp\market\event.cpp(689) : see > reference to function template instantiation 'boost::shared_ptr<T> > SohoEvents::StandardDayEvent::convertIntervals<eDivide,eMinus>(void) > const' being compiled > 1> with > 1> [ > 1> T=std::vector<SohoEvents::intervalPtr> > 1> ] > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'U', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: > 'boost::is_same' : use of class template requires template argument list > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'T', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'U', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: > 'boost::is_same' : use of class template requires template argument list > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'T', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'U', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: > 'boost::is_same' : use of class template requires template argument list > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'T', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'U', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: > 'boost::is_same' : use of class template requires template argument list > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2027: use of > undefined type 'boost::STATIC_ASSERTION_FAILURE<x>' > 1> with > 1> [ > 1> x=false > 1> ] > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'T', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1> d:\dev\13_1x\development\cpp\market\event.cpp(713) : see > reference to function template instantiation 'boost::shared_ptr<T> > SohoEvents::StandardDayEvent::convertIntervals<eMult,ePlus>(void) const' > being compiled > 1> with > 1> [ > 1> T=std::vector<SohoEvents::intervalPtr> > 1> ] > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'U', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: > 'boost::is_same' : use of class template requires template argument list > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'T', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'U', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: > 'boost::is_same' : use of class template requires template argument list > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'T', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'U', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: > 'boost::is_same' : use of class template requires template argument list > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'T', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: > 'boost::is_same' : invalid template argument for 'U', type expected > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: > 'boost::is_same' : use of class template requires template argument list > 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see > declaration of 'boost::is_same' > 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2027: use of > undefined type 'boost::STATIC_ASSERTION_FAILURE<x>' > 1> with > 1> [ > 1> x=false > 1> ] > 1>Build log was saved at > "file://d:\Dev\13_1X\Development\CPP\market\Debug\BuildLog.htm" > 1>Market - 26 error(s), 0 warning(s) > ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped > ========== > > ___________________________________________________________ > This e-mail may contain confidential and/or privileged information. If you are > not the intended recipient (or have received this e-mail in error) please notify > the sender immediately and delete this e-mail. Any unauthorised copying, > disclosure or distribution of the material in this e-mail is prohibited. > > Please refer to > http://www.bnpparibas.co.uk/en/information/legal_information.asp?Code=ECAS > -845C5H for additional disclosures. >

1 0

using boost::is_same with enums
by przemyslaw.sliwa＠uk.bnpparibas.com 27 May '11

27 May '11

Hello, I am trying to use boost::is_same in the folloting case enum eOperation { ePlus = 0, eMinus, eMult, eDivide }; template<eOperation P, eOperation Q> boost::shared_ptr<std::vector<intervalPtr> > convertIntervals() const { BOOST_STATIC_ASSERT( (boost::is_same<P, eDivide>::value && boost::is_same<Q, eMinus>::value) || (boost::is_same<P, eMult>::value && boost::is_same<Q, ePlus>::value)); static const double dNoOfSecsInADay(3600*24); boost::shared_ptr<std::vector<intervalPtr> > out(new std::vector<intervalPtr>(m_intervals.size())); // more code here return out; } Could someone help me with this? it does not compile at all on VC++2010. The error i get is 1>Pshemek -> this needs to be improved, no constructor calls at all when merged back to HEAD 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'T', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1> d:\dev\13_1x\development\cpp\market\event.cpp(689) : see reference to function template instantiation 'boost::shared_ptr<T> SohoEvents::StandardDayEvent::convertIntervals<eDivide,eMinus>(void) const' being compiled 1> with 1> [ 1> T=std::vector<SohoEvents::intervalPtr> 1> ] 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'U', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: 'boost::is_same' : use of class template requires template argument list 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'T', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'U', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: 'boost::is_same' : use of class template requires template argument list 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'T', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'U', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: 'boost::is_same' : use of class template requires template argument list 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'T', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'U', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: 'boost::is_same' : use of class template requires template argument list 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2027: use of undefined type 'boost::STATIC_ASSERTION_FAILURE<x>' 1> with 1> [ 1> x=false 1> ] 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'T', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1> d:\dev\13_1x\development\cpp\market\event.cpp(713) : see reference to function template instantiation 'boost::shared_ptr<T> SohoEvents::StandardDayEvent::convertIntervals<eMult,ePlus>(void) const' being compiled 1> with 1> [ 1> T=std::vector<SohoEvents::intervalPtr> 1> ] 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'U', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: 'boost::is_same' : use of class template requires template argument list 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'T', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'U', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: 'boost::is_same' : use of class template requires template argument list 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'T', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'U', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: 'boost::is_same' : use of class template requires template argument list 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'T', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2974: 'boost::is_same' : invalid template argument for 'U', type expected 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2955: 'boost::is_same' : use of class template requires template argument list 1> d:\dev\13_1x\thirdparty\boost\type_traits\is_same.hpp(37) : see declaration of 'boost::is_same' 1>d:\dev\13_1x\development\cpp\market\event.cpp(668) : error C2027: use of undefined type 'boost::STATIC_ASSERTION_FAILURE<x>' 1> with 1> [ 1> x=false 1> ] 1>Build log was saved at "file://d:\Dev\13_1X\Development\CPP\market\Debug\BuildLog.htm" 1>Market - 26 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== ___________________________________________________________ This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and delete this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is prohibited. Please refer to http://www.bnpparibas.co.uk/en/information/legal_information.asp?Code=ECAS-… for additional disclosures.

2 2

condensed overview of boost
by Olaf Krzikalla 27 May '11

27 May '11

Hi @boost, recently I've given some lectures about some selected boost libraries. After that the audience expressed the wish to get an overview over all current boost libraries. Thus for my next lecture I sat down and digged through the complete 1.46 for several day. I found a lot of useful stuff, but I also found a lot of obsolete, superseded, replaced or will-be-superseded stuff. Some libraries seems to be sub-libs of other libs. Is there an overview of inner lib relations and the actual lib state wrt. to the overall development? The issues I've found so far: - Compatibility: very narrow. Is it still needed as a public lib? - Functional, MemFun: superseded by Bind - Call Traits, Functional/Forward, Lambda: will be superseded by C++0x - Interval: can this become a sub-lib of ICL? - Meta State Machine / Statechart: whats the actual difference? I.e. which problem is solved by one lib but not by the other? - Fusion & Tuple: how are these related? Could boost::tuple become a typedef to boost::fusion::vector. I know that most of these relations are there for historical reasons and won't be changed. However I wish it had been documented somewhere. That would make an in-depth introduction of boost a lot easier. Best regards Olaf Krzikalla

5 8

[Interprocess] Shared memory misplaced
by Alexander Pérez Ruiz 26 May '11

26 May '11

Hi all, I have followed the discussion about the problems with the WMI in https://svn.boost.org/trac/boost/ticket/5392. I patched my release version of boost 1_46_1 with the wmi.patch but I do not achieve it works well. I am using the Interprocess library in order to interchange information between two programs that run in Windows but one of them was compiled in linux with the MinGW cross-compiling-environment on an Ubuntu 10.10 machine that uses this version of boost. I create the shared memory in the program compiled directly on Windows but it is created in the folder named "Select ...". When I start the second program, this program is looking for the shared memory in the folder named "200110523...". How can I found the same behaviour in the two programs in order to use the shared memory segment? Could somebody give me some help? Presently, I work on Windows XP and VS 2008. Thanks in advance. -- Alexander Pérez Ruiz Doctorado en Automatización Avanzada y Robótica Instituto de Organización y Control de Sistemas Industriales (IOC) Universidad Politécnica de Cataluña (UPC) Avenida Diagonal 647, piso 11 08028 Barcelona, España Tel: 934017748

1 0

[ICL] interval_map question
by Antal A. Buss 26 May '11

26 May '11

Hi all, I'm trying to use interval_map to implement some kind of range to value directory, but I have some non expected results. The test code I'm using is: ------------------------ #include <iostream> #include <boost/icl/interval_map.hpp> #include <boost/icl/discrete_interval.hpp> using namespace std; using namespace boost::icl; int main(int argc, char const **argv) { interval_map<size_t, int> imap; typedef discrete_interval<size_t> interval_t; imap += make_pair(construct<interval_t>(0, 7, interval_bounds::closed()),0); cout << "imap: " << imap << endl; imap.set(make_pair(construct<interval_t>(0, 0, interval_bounds::closed()),1)); cout << "imap: " << imap << endl; imap.erase(construct<interval_t>(3, 3, interval_bounds::closed())); cout << "imap: " << imap << endl; } ------------------------ The result I got is: imap: {} imap: {([0,0]->1)} imap: {([0,0]->1)} but the result I was expecting is: imap: {([0,7]->0)} imap: {([0,0]->1)((0,7]->0)} imap: {([0,0]->1)((0,3)->0)((3,7]->0)} Do I missing something? Thanks, Antal

2 2

serialization: BOOST_STATIC_WARNING
by Travis Gockel 25 May '11

25 May '11

I've recently had some trouble with C++'s implicit casting, so I'm looking for a way to warn people if somebody attempts to assign an int32_t to a uint64_t or whatever. BOOST_STATIC_ASSERT would work wonders for this, except that the code base I'm working with is quite large and relies on a lot of implicit casting, so immediately breaking everything with assertions is unrealistic. It looks like BOOST_STATIC_WARNING ( http://www.boost.org/doc/libs/1_46_1/libs/serialization/doc/static_warning.…) would be ideal for me, however, I cannot get it to actually emit a warning. I have attached a quick example of what I am looking for, but it essentially boils down to this not doing anything: typedef boost::is_same<int64_t, int32_t> same_type; BOOST_STATIC_WARNING(same_type::value); My compiler is g++ 4.4.3 with --std=c++0x -Wall -Wextra. Thanks! -- - Travis Gockel

2 2

Re: [Boost-users] [BGL] Subgraphs: Name-to-Index Property Map.
by Cedric Ginestet 25 May '11

25 May '11

> Dear Cedric L., > > Yes, you're right. It is true that the use of the filtered_graph seems > to be very appropriate. However, since I would still need to copy the > new graph, it is not clear whether this would save much computational > time. > > Thank you very much for your suggestion about using vertex_descriptor > instead of int. I already encountered some problems when switching > from vecS to listS, and couldn't understand where the error was > located. I will definitely follow your advice in the future. > > Regarding my use of int in vertex_name_t, instead of std::string. This > was indeed intended. My vertices are labelled with integers. Would you > still recommend that I use std::string to specify the names of these > vertices, even though they are integers? > > Your final suggestion made me realize that I already have the look-up > table that you mentioned. In fact, in my application, the names of the > vertices in the subgraph correspond to the indices of the vertices in > the main graph. It is therefore completely trivial to clear and remove > the vertices in the main graph, by using the names of the ones in the > subgraph! > > Thanks a lot, that was very useful. > Cedric G. > > Dear BGL users, > > > > I am trying to produce a simple routine to extract the subgraph of a > > graph, by using the vertex names of the subgraphs. That is, for two > > graphs G and H, I want to define the following operator: > > G -= H; > > Here, the resulting subgraph of G should have all the vertices that H > > doesn't have. During this process, the incident edges of the removed > > vertices are also removed. I have checked the subgraph class in BGL, but > > this refers to a substantially different concept. I have tried the > > following code, which works, but is extremely slow for the type of > > application that I had in mind: > > > > ////////////////////////////////////////////////// > > class Graph > > { > > public: > > typedef adjacency_list<vecS, vecS, undirectedS, > > property<vertex_name_t,int> > UndirectedGraph; > > Graph(); > > ~Graph(); > > int Nv(); // Return number of vertices > > Rcpp::IntegerVector V(); // Return vector of NAMES of vertices as > > integers. > > Graph& operator-= (Graph& H); > > private: > > UndirectedGraph G; > > }; > > > > ///////////////////////////////////////////////////////////////////////// > > // Overloaded Operators. > > Graph& Graph::operator-= (Graph& H){ > > typedef graph_traits<UndirectedGraph>::vertex_descriptor Vdescriptor; > > typedef property_map<UndirectedGraph,vertex_name_t>::type > > VertexNameMap; typedef iterator_property_map<int*, identity_property_map> > > name_to_vertex_map; > > > > Rcpp::IntegerVector vec = H.V(); > > VertexNameMap NameIndex; > > for(ivIter t=vec.begin(); t!=vec.end(); ++t){ > > > > // Create/Update Iterator map (LValuePropertyMap). > > int x[this->Nv()]; NameIndex = get(vertex_name,G); > > for(int i=0; i< this->Nv(); ++i) x[NameIndex[i]]=i; > > name_to_vertex_map NVmap(x); > > > > // Remove vertex from name of *t in H. > > Vdescriptor u=NVmap[*t]; > > clear_vertex(u,G); remove_vertex(u,G); > > }//t > > return *this; > > }//-> ////////////////////////////////////////////////// > > > > The problem seems to be that I re-create an iterator map (from vertex > > NAMES to vertex INDICES) every time I remove a single vertex. This seems > > counter-efficient. I would need to be able to create a reference to a > > similar map that is automatically updated every time I remove a vertex. > > However, since vertices in BGL are indexed from 0 to Nv-1, I don't see a > > way to produce a LValuePropertyMap from vertex's names to vertex's indices. > > > > Any help/opinion would be greatly appreciated, > > Maybe a soution would be to use filtered_graph and as the predicate the > vertices (or directly names) of H (in the form of a set?!). However, this > would require to copy the filtered_graph again into an adjacency_list, which > might be costly, depending on your situation. > Besides this, I would suggest you to use vertex_descriptor instead of int, as > vertex_descriptor is more general and your code will then most likely also > work if you decide to change vecS into listS (in case this plays a role). > Concerning your code, I am wondering if it is intended that vertex_name_t is > of type int and not std::string? > The more, when you want to compare each vertex from one graph with each vertex > of the other (which you basically have to do for completeness), I would assume > this takes quadratic running time and hence will be fairly costly. Unless you > have maps that allow a faster lookup, but you will then need to create a map > NAMES to INDICES(vertex_descriptor) for one graph and then do something like: > name_to_vertex_map_H[getName(vertex_of_G)] and in case this key exists, you > can remove vertex_of_G from G, as you have found a vertex with an equivalent > name in H. It would then also be nonrelevant if your graph (for simplicity I > take G) would have vertices with the same name, as they would all be "mapped" > by the name_to_vertex_map_H and thus could be adequately handled. I actually > don't see the need to update the map then, because the deleted vertices will > not show up again (your iterator went to the next vertex) and if there are > different nodes with the same name, they will be taken care of. > One thing that comes into my mind when writing you this is that you also > should have a look at iterator-invalidation due to the clear_vertex() and > remove_vertex(). I am right now not sure if this is critical for vecS or not. > > Hope that these thoughts are handy in some way. If not, please let me know. > > Best, > > Cedric > > > -- > Cedric Ginestet, PhD > Centre for Neuroimaging Sciences (L3.04) > NIHR Biomedical Research Centre > Department of Neuroimaging > Institute of Psychiatry, Box P089 > King's College London > De Crespigny Park > London > SE5 8AF > http://arxiv.org/find/q-bio/1/au:+Ginestet_C/0/1/0/all/0/1

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[GIL] bits8* to gray8_ptr_t without reinterpret_cast?
by Tyler Weston 25 May '11

25 May '11

You might have also seen this question on SO: http://stackoverflow.com/questions/6103252/boostgil-bits8-to-gray8-ptr-t-wi… Trying to work by the design guidelines for GIL, I use |bits__| for my channel data types. I often have external data I'm wrapping into GIL image views. However, even using the |bits__| types for data pointers, I have to add in a reinterpret_cast before I can create my image views. Take the following code |int width= 3; int height= 2; boost::gil::bits8 data8[] = {0, 1, 100, 200, 50, 51}; boost::gil::bits8* pBits8= data8; boost::gil::gray8_ptr_t pGray8= pBits8; boost::gil::gray8_view_t v= interleaved_view(width, height, pGray8, width* sizeof(boost::gil::bits8)); | Results in the error on line 6 "error C2440: 'initializing' : cannot convert from 'boost::gil::bits8 *' to 'boost::gil::gray8_ptr_t' 1> Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast" Delving into the source code as much as I can, it appears these types really are unreleated. bits8 is just |unsigned char|, but |gray8_ptr_t| is a pointer to a |struct pixel<bits8,gray_layout_t>|. The only element of this struct is a single bits8, so a reinterpret_cast looks safe. It also works fine for the tests I've thrown at it. However, I wrap external data into image views quite often, and having a reinterpret_cast in every place feels problematic. Is there a safer way of constructing a pixel pointer for use in GIL? My current workaround is to create a template specialized cast that only compiles for known safe casts. |template<class Dest, class Src> Dest gil_safe_ptr_cast(Src src) { // this cast is unsafe, use reinterpret_cast BOOST_STATIC_ASSERT(false); } template<> boost::gil::gray8_ptr_t gil_safe_ptr_cast(boost::gil::bits8* pBits8) { return reinterpret_cast<boost::gil::gray8_ptr_t>(pBits8); } boost::gil::bits8* pBits8= data8; boost::gil::gray8_ptr_t pGray8= gil_safe_ptr_cast<boost::gil::gray8_ptr_t>(pBits8); // works boost::gil::bits16* pBits16= NULL; boost::gil::gray8_ptr_t pGray82= gil_safe_ptr_cast<boost::gil::gray8_ptr_t>(pBits16); // compile error as expected | If this is the best current solution, I'd be glad to clean it up and pack it into typedefs.hpp for grayscale types. Thoughts?

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[BGL] Subgraphs: Name-to-Index Property Map.
by Cedric Ginestet 25 May '11

25 May '11

Dear BGL users, I am trying to produce a simple routine to extract the subgraph of a graph, by using the vertex names of the subgraphs. That is, for two graphs G and H, I want to define the following operator: G -= H; Here, the resulting subgraph of G should have all the vertices that H doesn't have. During this process, the incident edges of the removed vertices are also removed. I have checked the subgraph class in BGL, but this refers to a substantially different concept. I have tried the following code, which works, but is extremely slow for the type of application that I had in mind: ////////////////////////////////////////////////// class Graph { public: typedef adjacency_list<vecS, vecS, undirectedS, property<vertex_name_t,int> > UndirectedGraph; Graph(); ~Graph(); int Nv(); // Return number of vertices Rcpp::IntegerVector V(); // Return vector of NAMES of vertices as integers. Graph& operator-= (Graph& H); private: UndirectedGraph G; }; ///////////////////////////////////////////////////////////////////////// // Overloaded Operators. Graph& Graph::operator-= (Graph& H){ typedef graph_traits<UndirectedGraph>::vertex_descriptor Vdescriptor; typedef property_map<UndirectedGraph,vertex_name_t>::type VertexNameMap; typedef iterator_property_map <int*, identity_property_map> name_to_vertex_map; Rcpp::IntegerVector vec = H.V(); VertexNameMap NameIndex; for(ivIter t=vec.begin(); t!=vec.end(); ++t){ // Create/Update Iterator map (LValuePropertyMap). int x[this->Nv()]; NameIndex = get(vertex_name,G); for(int i=0; i < this->Nv(); ++i) x[NameIndex[i]]=i; name_to_vertex_map NVmap(x); // Remove vertex from name of *t in H. Vdescriptor u=NVmap[*t]; clear_vertex(u,G); remove_vertex(u,G); }//t return *this; }//-= ////////////////////////////////////////////////// The problem seems to be that I re-create an iterator map (from vertex NAMES to vertex INDICES) every time I remove a single vertex. This seems counter-efficient. I would need to be able to create a reference to a similar map that is automatically updated every time I remove a vertex. However, since vertices in BGL are indexed from 0 to Nv-1, I don't see a way to produce a LValuePropertyMap from vertex's names to vertex's indices. Any help/opinion would be greatly appreciated, -- Cedric Ginestet Centre for Neuroimaging Sciences (L3.04) NIHR Biomedical Research Centre Department of Neuroimaging Institute of Psychiatry, Box P089 King's College London De Crespigny Park London SE5 8AF

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iostreams stream file error
by Kraus Philipp 25 May '11

25 May '11

Hello, I use this code excerpt for copy file content: bio::stream< bio::basic_file_source<char> > l_file(p_str1); if (!l_file.is_open()) throw exception::runtime(_("file can not be opened")); std::copy( std::istream_iterator<char>(l_file), std::istream_iterator<char>(), std::ostreambuf_iterator<char>(&l_deflate) ); (*) l_file.close(); p_str1 is the filename and bio ist shorten for boost::iostreams, l_deflate is a bio::filtering_streambuf< bio::output > with a bzip2 compressor. I can set anything else to p_str1 (some not existing filesnames) and the code runs not into the if construction, the std::copy seems to copy any data, but which if there is no file under the stream !? The l_deflate is define with: bio::counter l_counter; bio::basic_null_sink<char> l_null; bio::filtering_streambuf< bio::output > l_deflate; l_deflate.push( bio::bzip2_compressor( m_bzip2param ) ); break; l_deflate.push( boost::ref(l_counter) ); l_deflate.push( l_null ); I would count the compressed bytes of a file (without writing the file), but I need to copy the filecontent without closing after copying, so I can't use boost::iostream::copy (it closes the streams after copy). On the (*) can be some other std::copy with other files Can anyone help me please to create a correct code ? Thanks a lot Phil

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