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Date_Time library question...
by Luc Bergeron 29 Nov '02

29 Nov '02

Hello everyone, I was wondering, while looking at the source files, why the date_iterator doesn't provide an operator--() ??? I've added this in the "date_iterator.hpp" file : //--------------------------------------------------------- date_itr_base& operator--() { current_ = current_ - get_offset(current_); return *this; } //--------------------------------------------------------- I've rebuilt the library and done this little test : //--------------------------------------------------------- #include <iostream> #include <boost/date_time/gregorian/gregorian.hpp> int main(void) { using namespace boost::gregorian; date today = day_clock::local_day(); day_iterator ditr(today, 1); int nbDaysToIterate = 360; for (;nbDaysToIterate != 0; --ditr, --nbDaysToIterate) { std::cout << to_iso_extended_string(*ditr) << std::endl; } } //--------------------------------------------------------- Everything seems to run OK. I've checked the february month and it has a 28th... Now I wonder why wasn't it included in the release ??? Cheers. Luc Bergeron.

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Using function_traits
by Marshall Clow 29 Nov '02

29 Nov '02

I'm trying to use the function traits to extract the return type of a template parameter, but it's not compiling. Any ideas what's wrong here? -------- begin simplified code ------ template<typename Proc> class CacheValue { typedef boost::function_traits<Proc>::R ReturnType; template<typename Arg1> ReturnType operator () ( Arg1 arg1 ) { /* do something */ } }; CacheValue<unsigned long (*) ( unsigned long )> aValue; -------- end simplified code ------ Gets the error: Error : illegal use of incomplete struct/union/class 'boost::detail::function_traits_helper<unsigned long (**)(unsigned long)>' (point of instantiation: 'main()') (instantiating: 'CacheValue<unsigned long (*)(unsigned long)>') (instantiating: 'boost::function_traits<unsigned long (*)(unsigned long)>') function_traits.hpp line 170 public detail::function_traits_helper<typename add_pointer<Function>::type> Error : 'R' is not a member of class 'boost::function_traits<unsigned long (*)(unsigned long)>' (point of instantiation: 'main()') (instantiating: 'CacheValue<unsigned long (*)(unsigned long)>') HelloWorld.cp line 57 CacheValue<TickGetter> ticks ( GetCount ); Environment: MacOS 10.2.2, CodeWarrior 8.3, boost from CVS this morning. It seems as if the "add_pointer" in function_traits_helper is messing things up. Of course, it's more likely that I am using this wrong ;-) Thanks in advance! -- -- Marshall Marshall Clow Idio Software <mailto:marshall@idio.com> Hey! Who messed with my anti-paranoia shot?

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boost::iterator_adaptor
by Julia Donawald 29 Nov '02

29 Nov '02

Hi, I am trying to write my own iterator - class and using for that the boost::iterator_adaptor. I could find on the webpage several examples of how to connect an existing iterator like std::string::iterator or a simple array as "base-class" for my new iterator, but what can I do if I dont have any base-iterator? In the documentation I found the following sentence: "The Iterator Adaptor library allows you transform an arbitrary ``base'' type into a standard-conforming iterator with the behaviors you choose. Doing so is especially easy if the ``base'' type is itself an iterator." In my situation I dont have any base type which is an iterator ( as base type I have a simple int ), so how should I now create such a base-type? Which are the specifications of such a base-type? Where can I get information on how to create a new base-type? I am trying to write an iterator which reads records from a file or a database and always when I do the it++ the next record is read from the file or database. Bye, Julia

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Re: [Boost-Users] ublas::matrix sharing storage with ublas::vecto r
by Stephen Crowley 28 Nov '02

28 Nov '02

On Thu, Nov 28, 2002 at 09:12:53AM -0500, Toon Knapen wrote: > On Wednesday 27 November 2002 20:46, Stephen Crowley wrote: > > What do you mean by "just use it as" ? > > > > For example.. I have a matrix<double> m(5,5); > > > > In some code I actually need to use it as a 5x5 matrix.. but other parts > > must reference it as a vector (to pass to another library). > > OK, So as to get to the bottom of this. Do you really want to perform vector > operations on a vector that consists of a concatenation of all rows (or > columns) of the matrix do you want to get access to the storage to pass your > information to another library. > > The latter case is dealt with in the boost-sandbox/boost/numeric/bindings. > There we've spend effort to be able to extract the begin- and end-pointer > (not iterator) from any vector or matrix. (In the bindings it's used to pass > these pointers to e.g. BLAS) > > In the former case, could you enlighten me what kind of numeric operations > you're dealing with ? The matrix I am working with is a set of weights for a neural net. I am using a kalman filtering library (http://www.acfr.usyd.edu.au/technology/bayesianfilter/Bayes++.htm) that treats the weights as a vector. So, I'm not really sure how to answer your question. I guess I would say that I need to access a vector as a concatenation of the rows or columns of the matirx (for this purpose it does not matter as long as it is consistent). However, copying undering data() member is working for now, although not as quickly as I would like. -- Stephen

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RE: [Boost-Users] ublas::matrix sharing storage with ublas::vecto r
by Scott Sinclair 28 Nov '02

28 Nov '02

Hi Stephen Yes, just use a (1, n) or (n, 1) matrix as appropriate and do matrix operations instead of vector ops. The results will be correct as long as you make sure you have a correctly dimensioned matrix in place of your vector (i.e one that matches your vectors size and orientation). After all a matrix is just a collection of vectors ;-) cheers, Scott On 27/11/2002 05:10, Stephen Crowley wrote > It is possible for a vector and a matrix to share the same storage, as > long as the dimensions agree? > > Some of the algorithms I am implementing require some objects > to be treated > as an arbitrarily sized matrix, and sometimes as a vector, > and it would be > convient to have a matrix and a vector share the same memory. > > -- > Stephen The contents of this email may be confidential. Unauthorised use is prohibited. Umgeni Water does not accept liability for any statements and opinions which are the sender's own view and not expressly made on its behalf.

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RE: [Boost-Users] MSVC++, bind and namespaces
by Antoine Boivin Filion 28 Nov '02

28 Nov '02

Hi, FYI, the code below compiles and runs OK on MSVC++7... so you might just be right! Regards, Antoine -----Original Message----- From: Andre Hentz [mailto:ahentz@cariden.com] Sent: November 28, 2002 09:42 To: Boost-Users(a)yahoogroups.com Subject: [Boost-Users] MSVC++, bind and namespaces I've just encountered this problem and it looks like a MS bug. Not sure it deserves a Boost workaround but I thought it would be nice to let you know (in case you don't already). Here's the code: #include <boost/bind.hpp> namespace A{ struct c{ void setName(const char*) {} }; } namespace B{ struct c{ void setName(const char*) {} }; } using namespace B; using namespace A; int main() { boost::bind(&A::c::setName, _1, _2); return 0; } It looks legal to me but I'm no expert. GCC compiles with no warnings but MSVC++ 6sp5 gives the error below. boost/bind/mem_fn_vw.hpp(29) : error C2872: 'c' : ambiguous symbol boost/bind.hpp(875) : see reference to class template instantiation 'boost::_mfi::mf1<void ,struct A::c,char const *>' being compiled boost/bind.hpp(886) : see reference to class template instantiation 'boost::_bi::bind_t_generator<void>::implementation<struct boost::_mfi::mf1<void,struct A::c,char const *>,class boost::_bi::list2<class boost::arg<1>,class boost::arg<2> > >' being compiled test.cpp(15) : see reference to class template instantiation 'boost::_bi::bind_t<void,struct boost::_mfi::mf1<void,struct A::c,char const *>,class boost::_bi::list2<class boost::arg<1>,cla ss boost::arg<2> > >' being compiled boost/bind/mem_fn_vw.hpp(31) : error C2872: 'c' : ambiguous symbol boost/bind.hpp(875) : see reference to class template instantiation 'boost::_mfi::mf1<void,struct A::c,char const *>' being compiled boost/bind.hpp(886) : see reference to class template instantiation 'boost::_bi::bind_t_generator<void>::implementation<struct boost::_mfi::mf1<void,struct A::c,char const *>,class boost::_bi::list2<class boost::arg<1>,class boost::arg<2> > >' being compiled test.cpp(15) : see reference to class template instantiation 'boost::_bi::bind_t<void,struct boost::_mfi::mf1<void,struct A::c,char const *>,class boost::_bi::list2<class boost::arg<1>,class boost::arg<2> > >' being compiled Best, Andre Hentz Yahoo! Groups Sponsor ADVERTISEMENT <http://rd.yahoo.com/M=237459.2675695.4055211.2225243/D=egroupweb/S=17050067 88:HM/A=1267611/R=0/*http://ad.doubleclick.net/jump/N2524.Yahoo/B1071650;sz= 300x250;ord=1038499880908608?> <http://us.adserver.yahoo.com/l?M=237459.2675695.4055211.2225243/D=egroupmai l/S=:HM/A=1267611/rand=601430356> Info: < http://www.boost.org <http://www.boost.org> > Wiki: < http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service <http://docs.yahoo.com/info/terms/> . [Non-text portions of this message have been removed]

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Re: [Boost-Users] ublas::matrix sharing storage with ublas::vecto r
by Toon Knapen 28 Nov '02

28 Nov '02

On Wednesday 27 November 2002 20:46, Stephen Crowley wrote: > What do you mean by "just use it as" ? > > For example.. I have a matrix<double> m(5,5); > > In some code I actually need to use it as a 5x5 matrix.. but other parts > must reference it as a vector (to pass to another library). OK, So as to get to the bottom of this. Do you really want to perform vector operations on a vector that consists of a concatenation of all rows (or columns) of the matrix do you want to get access to the storage to pass your information to another library. The latter case is dealt with in the boost-sandbox/boost/numeric/bindings. There we've spend effort to be able to extract the begin- and end-pointer (not iterator) from any vector or matrix. (In the bindings it's used to pass these pointers to e.g. BLAS) In the former case, could you enlighten me what kind of numeric operations you're dealing with ? toon -------------------------------------------------------

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MSVC++, bind and namespaces
by Andre Hentz 28 Nov '02

28 Nov '02

I've just encountered this problem and it looks like a MS bug. Not sure it deserves a Boost workaround but I thought it would be nice to let you know (in case you don't already). Here's the code: #include <boost/bind.hpp> namespace A{ struct c{ void setName(const char*) {} }; } namespace B{ struct c{ void setName(const char*) {} }; } using namespace B; using namespace A; int main() { boost::bind(&A::c::setName, _1, _2); return 0; } It looks legal to me but I'm no expert. GCC compiles with no warnings but MSVC++ 6sp5 gives the error below. boost/bind/mem_fn_vw.hpp(29) : error C2872: 'c' : ambiguous symbol boost/bind.hpp(875) : see reference to class template instantiation 'boost::_mfi::mf1<void ,struct A::c,char const *>' being compiled boost/bind.hpp(886) : see reference to class template instantiation 'boost::_bi::bind_t_generator<void>::implementation<struct boost::_mfi::mf1<void,struct A::c,char const *>,class boost::_bi::list2<class boost::arg<1>,class boost::arg<2> > >' being compiled test.cpp(15) : see reference to class template instantiation 'boost::_bi::bind_t<void,struct boost::_mfi::mf1<void,struct A::c,char const *>,class boost::_bi::list2<class boost::arg<1>,cla ss boost::arg<2> > >' being compiled boost/bind/mem_fn_vw.hpp(31) : error C2872: 'c' : ambiguous symbol boost/bind.hpp(875) : see reference to class template instantiation 'boost::_mfi::mf1<void,struct A::c,char const *>' being compiled boost/bind.hpp(886) : see reference to class template instantiation 'boost::_bi::bind_t_generator<void>::implementation<struct boost::_mfi::mf1<void,struct A::c,char const *>,class boost::_bi::list2<class boost::arg<1>,class boost::arg<2> > >' being compiled test.cpp(15) : see reference to class template instantiation 'boost::_bi::bind_t<void,struct boost::_mfi::mf1<void,struct A::c,char const *>,class boost::_bi::list2<class boost::arg<1>,class boost::arg<2> > >' being compiled Best, Andre Hentz

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Re: [Boost-Users] ublas::matrix sharing storage with ublas::vecto r
by Toon Knapen 28 Nov '02

28 Nov '02

On Wednesday 27 November 2002 20:46, Stephen Crowley wrote: > What do you mean by "just use it as" ? > > For example.. I have a matrix<double> m(5,5); > > In some code I actually need to use it as a 5x5 matrix.. but other parts > must reference it as a vector (to pass to another library). OK, So as to get to the bottom of this. Do you really want to perform vector operations on a vector that consists of a concatenation of all rows (or columns) of the matrix do you want to get access to the storage to pass your information to another library. The latter case is dealt with in the boost-sandbox/boost/numeric/bindings. There we've spend effort to be able to extract the begin- and end-pointer (not iterator) from any vector or matrix. (In the bindings it's used to pass these pointers to e.g. BLAS) In the former case, could you enlighten me what kind of numeric operations you're dealing with ? toon

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RE: [Boost-Users] Is intrusive_ptr the thing to use?
by Hickman, Greg 28 Nov '02

28 Nov '02

From: Peter Dimov [mailto:pdimov@mmltd.net] > From: "Hickman, Greg" <greg.hickman(a)lmco.com> > > > From: Peter Dimov [mailto:pdimov@mmltd.net] > > > If 'f' is virtual, have the object store a weak_ptr to itself: > > > > > > class X > > > { > > > private: > > > > > > weak_ptr<X> weak_this; > > > > > > X(); > > > X(X const &); > > > X& operator=(X const &); > > > > > > public: > > > > > > static shared_ptr<X> create() > > > { > > > shared_ptr<X> px(new X); > > > px->weak_this = px; > > > return px; > > > } > > > > I must be missing something here, because it appears as though you > > can't derive a Y from X and still initialize X::weak_this. > > You could simply make X::weak_this and X::X() protected... > although if you follow the design rule that says that > non-leaf classes should be abstract (and if possible contain > no data) this shouldn't be necessary, as X as pictured above > would be a leaf. Its seems the leaf itself must implement the factory method/weak_this idiom. This initially didn't seem like a good idea in our case since clients write the leaves - we only provide X. But on second thought, perhaps two alternatives are (1) provide a helper template for clients to use when deriving from X to automatically declare the static create()/weak_this pair, or (2) use an intrusive reference counting approach for X. If an intrusive approach ultimately works better for us, what should I do as a boost 1.29.0 user: use counted_base/shared_from_this, or intrusive_ptr (which I admittedly haven't even looked at)? Any suggestions you have are more than welcome. -Greg

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