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BoostCon '09 Sessions
by David Abrahams 05 Mar '09

05 Mar '09

Hartmut Kaiser and the BoostCon Program committee have done a stellar job assembling a list of sessions for this year's BoostCon, including everything from C++ compiler developer presentations, to hands-on C++0x development, to talks on eexperimental metaprogramming enhancements, to expression templates for running code on GPUs. I can honestly say I want to go to almost every session. It's going to be hard to choose. Please see the session list at: http://www.boostcon.com/program/sessions and then, of course, head on over to http://www.boostcon.com/registration to register for the conference. Best regards to all. See you there! -- Dave Abrahams BoostPro Computing http://www.boostpro.com

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[iostreams] with compression filters?
by Mikko Vainio 05 Mar '09

05 Mar '09

Dear boosters, I'm trying to compile IOStreams from 1.38.0 with bzip2 compression enabled on windows. The docs say "you will need to set variables indicating the location of the source files". Setting boost.build variables in user-config.jam doesn't seem to do the trick. Providing "-s|BZIP2_SOURCE|=..." or any of the other related variables or combinations thereof on the command line for bjam does not help. Does anyone out there have an example on how to do this exactly? I suggest such an example to be added to the documentation. Or is this a bug in the build system? Regards, Mikko

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bind member function of a member of a class...
by Archie14 05 Mar '09

05 Mar '09

I cannot figure out how to use boost::bind in following scenario: class A { int i_; public: int test() {return i;} }; class B { A _a; public: A& getA() {return _a;} } bool testbind() { B b; // here I am trying to find out if b.getA().test() equals 1 // I understand that B::getA::test is incorrect, and that's my question- // how to use bind here? return (boost::bind (&B::getA::test, b) ==1); }

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Re: [Boost-users] Boost-users Digest, Vol 1924, Issue 10
by Rob Currey 04 Mar '09

04 Mar '09

> From: "Peter Dimov" <pdimov(a)pdimov.com> > Subject: Re: [Boost-users] [enable_shared_from_this] My derivation > ofenable_shared_from_this wants to be templated >> template<class X> >> class Y: public enable_shared_from_this< Y<X> > >> { >> public: >> >> shared_ptr< Y<X> > f() >> { >> return shared_from_this(); > > In a template, you need > > return this->shared_from_this(); > > to inform the compiler that shared_from_this will come from a base class. > >> } perfect ... thank you.

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Calling date_time time_input_facet directly
by Jeffery Cavallaro 04 Mar '09

04 Mar '09

I have to parse a leading timestamp in a bunch of records, and I would like to avoid having to copy each record into a stringstream just to parser the timestamp. Does anyone know how to call the date_time time_input_facet directly? I did something like the following: char buffer[N]; typedef boost::date_time::time_input_facet<boost::posix_time::ptime, char, char *> TimeFacet; TimeFacet *f = new TimeFacet; boost::posix_time::ptime t; f->get(buffer, buffer + size, ???, t); But I don't know what to pass for the 3rd arg, which is an ios_base &. I tried an ios instance and a stringstream instance, but I couldn't get anything to work - the compiler can't seem to match the call. -- Jeffery Cavallaro, MTV-45-208G Infrastructure Engineering Google Inc. 1600 Amphitheatre Parkway Mountain View, CA 94043 650-214-2552

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VS 2008 Link1104 Error
by Mantas Matelis 04 Mar '09

04 Mar '09

Hello everyone, I've just built the boost libraries and I'm trying to get visual studio 2008 to properly recognize the libraries. The library that the linker is looking for is in C:\development\boost\build\boost\bin.v2\libs\filesystem\build\msvc-9.0\debug\link-static\threading-multi\libboost_filesystem-vc90-mt-gd-1_38.lib Even though I've added C:\development\boost\build\boost\bin.v2\libs to the extra libraries vc++ global setting. Error Message: 1>LINK : fatal error LNK1104: cannot open file 'libboost_filesystem-vc90-mt-gd-1_38.lib' If I add C:\development\boost\build\boost\bin.v2\libs\filesystem\build\msvc-9.0\debug\link-static\threading-multi to the project extra library setting though, the program compiles and links properly. On MSDN, http://msdn.microsoft.com/en-us/library/ts7eyw4s.aspx I've seen nothing that I think applies to me. So, what do I do?

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Re: [Boost-users] re alization of Last Recently Used cache with boost::multi_index
by Joaquin M Lopez Munoz 04 Mar '09

04 Mar '09

Hi Pavel, pavel5 wrote: > > I am trying to realize class for strings caching using boost::multi_index. > [...] > My class works without any problem, but i want to have template class, for > easily type of key and value selection. I modified my source: > [...] > After modification, gcc compiler prints for line: > > LRUCacheItems::nth_index<0>::type& hash_index=cache.get<0>(); > > many errors:[...] > Replace the offending line with typename LRUCacheItems::nth_index<0>::type& hash_index=cache.template get<0>(); Note the extra "typename" and also the "template" keyword between "cache." and "get<0>()". After templatizing your LRUCache, the expression happens to be in a so-called dependent context, and turns out you've got to help the compiler figure it out right (i.e. disambiguate from some other interpretations theoretically possible in the given context). Learn more about this issue at http://www.informit.com/guides/content.aspx?g=cplusplus&seqNum=388 Hope this helps, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo -- View this message in context: http://www.nabble.com/realization-of-Last-Recently-Used-cache-with-boost%3A… Sent from the Boost - Users mailing list archive at Nabble.com.

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boost::bind used with boost shared_ptr
by Kevin Ludwig 04 Mar '09

04 Mar '09

Hi, I've recently been making more use of boost::bind, and I coded the following, which I thought would work: class A { public: void reset () {} }; typedef std::map<int, boost::shared_ptr<A> > map_type; map_type m; std::for_each (m.begin(), m.end(), boost::bind(&A::reset, boost::bind(&map_type::value_type::second, _1))); but fails to compile. Next I tried this: std::for_each (m.begin(), m.end(), boost::bind(&A::reset, boost::bind(&boost::shared_ptr<A>::get, boost::bind(&map_type::value_type::second, _1)))); Which works and is fine (I guess). I just wonder why the first syntax is not supported? boost::shared_ptr is supposed to behave like a pointer (and here it seems that it does not). -- Kevin

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[enable_shared_from_this] My derivation of enable_shared_from_this wants to be templated
by Rob Currey 04 Mar '09

04 Mar '09

Here's some code based upon the example at : http://www.boost.org/doc/libs/1_38_0/libs/smart_ptr/enable_shared_from_this… class X { public: X() { }; }; template<class X> class Y: public enable_shared_from_this< Y<X> > { public: shared_ptr< Y<X> > f() { return shared_from_this(); } }; typedef Y<X> templatedY; int main() { shared_ptr<templatedY> p(new Y<X>); shared_ptr<templatedY> q = p->f(); assert(p == q); assert(!(p < q || q < p)); // p and q must share ownership } compiles with: $ gcc -o test -I/usr/local/include/boost-1_38 -lstdc++ -L/usr/local/lib -lboost_system-gcc41-mt test.cpp test.cpp: In member function âboost::shared_ptr<Y<X> > Y<X>::f()â: test.cpp:13: error: there are no arguments to âshared_from_thisâ that depend on a template parameter, so a declaration of âshared_from_thisâ must be available test.cpp:13: error: (if you use â-fpermissiveâ, G++ will accept your code, but allowing the use of an undeclared name is deprecated) Any resolution (other than the -fpermissive hack) TIA (my skilz with shared_ptr<> are somewhat lacking ...)

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[iterators ]bug?
by bismuth＠list.ru 04 Mar '09

04 Mar '09

There is probably a bug in boost::iterators library. boost::transform_iteartor degrade stl iterator_category. There is a code below, illustrating a problem(using VS2008 c++ compiler): --------------------- #include <stdio.h> #include <tchar.h> #include <vector> #include <boost/iterator/transform_iterator.hpp> #include <boost/static_assert.hpp> struct Tr1: std::unary_function<unsigned, unsigned> { unsigned operator()(unsigned a)const { return a; } }; int _tmain(int argc, _TCHAR* argv[]) { typedef std::vector<unsigned>::iterator some_ra_iterator_t; typedef boost::transform_iterator<Tr1, some_ra_iterator_t> tr_iter_t; BOOST_STATIC_ASSERT (( boost::is_convertible < std::iterator_traits<some_ra_iterator_t>::iterator_category, std::random_access_iterator_tag >::value )); BOOST_STATIC_ASSERT (( ! boost::is_convertible < std::iterator_traits<tr_iter_t>::iterator_category, std::random_access_iterator_tag >::value )); BOOST_STATIC_ASSERT (( boost::is_same < std::iterator_traits<tr_iter_t>::iterator_category, boost::detail::iterator_category_with_traversal < std::input_iterator_tag, //?! boost::random_access_traversal_tag > >::value )); return 0; } ---------------------

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