March 2009 - Boost - lists.preview.boost.org

[soc2009] Proposal for serialization library
by Hrvoje Ban 19 Mar '09

19 Mar '09

Dear Boost developers, Congratulations on being accepted as a mentoring organization. I'd like to work on Boost serialization library for this year Google Summer of Code. The feature I'd like, JSON archives, was suggested last year, but to my knowledge wasn't implemented. As part of my college project I have written LR(1) parsers for BBCode and Wiki Creole markup using JavaCup/JFlex, and also LL parser for BBCode using ANTLR. I'm not (jet) comfortable with Boost.Spirit, but since I'm quite familiar with (E)BNF notation, I can learn it quickly. I'd like to know are you still interested in this proposal and will there be mentor for me, if I get accepted? Sincerely, Hrvoje Ban

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Exposing command line options within Jamroot
by brook＠biology.nmsu.edu 19 Mar '09

19 Mar '09

I am helping to maintain the pkgsrc packages for Boost. When compiling the shared libraries it is important to inject rpath information into them so that the linker will correctly find dependencies. Thus, I would like to add a <dll-path> clause to the following stanza in Jamroot. # Install just library. install stage-proper : libs/$(libraries)/build : <location>$(stage-locate)/lib <install-dependencies>on <install-type>LIB <install-no-version-symlinks>on ; explicit stage-proper ; The obvious thing is to use something like <dll-path>$(libdir) or <dll-path>$(lib-locate) since those variables should be derived from the various bjam command line options or defaults. However, this variable (as well as the other obvious candidates like $(prefix), $(exec_prefix), etc.) do not seem to be defined within the context of Jamroot. The only place I am aware of these command line arguments being handled is deep within boost/tools/build/v2/tools/package.jam, in which case they are part of the install rule. I am guessing that burying the logic like that prevents the variables from being useful anywhere else, but I know very little about how bjam actually works. Thus, I believe there are two options: - Modify Jamroot itself or some other *.jam file to expose these variables (prefix, exec_prefix, etc. or some appropriate subset of them) so that command line options can better control what bjam does. - Modify Jamroot to introduce a new command line argument (e.g., --dll-path) and variable ($(dll-path)) to use for this specific purpose. I would like the solution to be one that will be acceptable into the Boost code base. Please advise me on how to proceed. Thank you very much. Cheers, Brook

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Re: [boost] [gsoc][student] Proposal
by Joseph Gauterin 19 Mar '09

19 Mar '09

You're proposal has significant overlap with Crypto++ (public domain). You might want to investigate some sort of code sharing, or at least have a look at how they've done things.

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[gsoc][student] Proposal
by Kasra 19 Mar '09

19 Mar '09

Hi, My proposal is to have a crypto library that provides high-level facilities. The library has different encapsulation layers. Within the low-level (internal) there are algorithms that share the same concept i.e. class block_cipher_type: + setkey(const void* key, size_type key_size) -> void; + encrypt(void* output, const void* input) -> const void; + decrypt(void* output, const void* input) -> const void; class stream_cipher_type: + create() -> void; + update(const void* input, size_type output) -> void; + update_final_block(const void* input, size_type output) -> void; and etc. Also entropy sources that use kernel specific entropies with addition of asynchronous generators. Finally a std:: iostream interface for cryptographically transformed streams. That use a transformer for the cryptographical transformation. Any interest??? -- Kasra

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range transformed -adaptor incompatible with lambda functions
by Sandeep Gupta 19 Mar '09

19 Mar '09

Hi, I would be nice if range-transformed worked with lambda functions. Is this an intended behaviour. To illustrate the following two statements fail for_each(myvec|boost::adaptors::transformed(arg1+mask), std::cout<<arg1<<' '); for_each(myvec|boost::adaptors::transformed(boost::lambda::_1 + mask), std::cout<<boost::lambda::_1<<' '); But this is fine: for_each(myvec|boost::adaptors::transformed(double_int()), std::cout<<boost::lambda::_1<<' '); where double_int hand created function object with result_type declaration. Thanks sandeep

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Boost.Asio and Steinberg ASIO
by Alexander Churanov 19 Mar '09

19 Mar '09

Hi folks! I wonder how Boost.Asio is related to Steinberg ASIO? It seems that ASIO is an older technology and it's name is a registered trademark. http://www.steinberg.net/en/company/steinberg_technology.html It's a source for confusion. For the first time I've noticed the Boost.Asio library, I was thinking it's an STL-compliant facade for Steinberg ASIO :-) Alexander Churanov

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[gsoc][student] Proposal
by Kasra 19 Mar '09

19 Mar '09

Hi All, I was wondering how the community is feeling about a new library proposal? Since few month ago I started talking about boost.crypto on the mailing list and considered its implications with few (namely Kevin Sopp). At present the library has more than 60K LOC. Any thought? :D -- Kasra Nassiri

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[asio] global timer cancellation?
by Brian and Victoria 19 Mar '09

19 Mar '09

Hi, I've got various objects that make use of the asio deadline timer to schedule events. The problem is that there isn't a central repository of timer references that I can walk to cancel them when shutting down asio. I'd like to be able to just tell asio to cancel any pending work and have the thread(s) return. Is this possible? I came across the io_service::work class but haven't yet found an example of how it works. Thanks, Brian

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dynamic_bitset count
by Andreas Klein 19 Mar '09

19 Mar '09

Hello. Sorry for multiple posts. Hopplfully I got I now right. ----------------------------------------------------- Dear boost developers, I checked the implementation of boost::dynamic_bitset::count and find that it uses a table look up. This is not optimal. First on 64-bit machines divide-and-conquer algorithms are faster than table look up and save even memory. Second if the bitset contains several words, there are for both 32 and 64 bit machines population count algorithms that are faster than the simple loop over all words used by boost. Together with Y. Edel I developed a new version,which saves 60% against the simple algorithm. We put the code online (http://cage.ugent.be/~klein/popc.html) A disadvantage of our implementation is that we relay on aggressive optimization (-O3) of the compiler. If you are searching a compromise between speed and code complexity. The first iteration of the Harley-Seal-method (25% faster than the simple loop) would be a candidate. You find this and other population count algorithms on our homepage, too. If there is interest I can add one of the advance algorithms in boost. Best wishes Andreas Klein

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[shared_ptr] calling shared_from_this from constructor
by Пюрецкий 18 Mar '09

18 Mar '09

Hi, A have just get latest version from SVN. And now my code does not work. I found problem in a changed version of shared_ptr and shared_from_this (revision 51485). Now calling shared_from_this in constructor throw's boost::bad_weak_ptr exception. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.

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boost::is_less::result_type
by Arno Schödl 18 Mar '09

18 Mar '09

Shouldn't boost::is_less et. al. define typedef bool result_type; for interoperability with boost::bind? Arno -- Dr. Arno Schoedl · aschoedl(a)think-cell.com Technical Director think-cell Software GmbH · Invalidenstr. 34 · 10115 Berlin, Germany http://www.think-cell.com · phone +49-30-666473-10 · toll-free (US) +1-800-891-8091 Directors: Dr. Markus Hannebauer, Dr. Arno Schoedl · Amtsgericht Charlottenburg, HRB 85229

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Google SOC Mentors?
by John Maddock 18 Mar '09

18 Mar '09

Would folks willing to mentor students for this years GSOC please step forward and make themselves known? We need both people to assist in assessing the student applications, and experienced Boosters to mentor the students themselves. We really need to get some new blood into this if our SOC participation is to continue - we can't rely on the "usual suspects" taking this on year after year - in short, "Your Boost Needs You!". Regards, John Maddock.

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Re: [boost] [lexical_cast] Strange behaviour
by raindog＠macrohmasheen.com 18 Mar '09

18 Mar '09

What exactly do you think -1 is as an unsigned int? ------Original Message------ From: Robert Jones Sender: boost-bounces(a)lists.boost.org To: boost(a)lists.boost.org ReplyTo: boost(a)lists.boost.org Sent: Mar 18, 2009 9:03 AM Subject: [boost] [lexical_cast] Strange behaviour Trying again 'cos I mucked up the code last time! This code #include <iostream> #include <boost/lexical_cast.hpp> int main() { using namespace std; try { unsigned int u=boost::lexical_cast<unsigned int>("-1"); cout << u << '\n'; } catch(const std::exception&) { cout << "Exception" << '\n'; } } produces 4294967295 on MSVC7 & 8 rather than an exception. Is it supposed to do this? Rob. _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost Sent from my Verizon Wireless BlackBerry

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Re: [boost] Range_Ex and Multi-Index: conflicting mpl::begin and boost::begin
by JOAQUIN M. LOPEZ MUÑOZ 18 Mar '09

18 Mar '09

________________________________________ De: boost-bounces(a)lists.boost.org [boost-bounces(a)lists.boost.org] En nombre de Joaquin M Lopez Munoz [joaquin(a)tid.es] Enviado el: miércoles, 18 de marzo de 2009 19:49 Para: boost(a)lists.boost.org Asunto: Re: [boost] Range_Ex and Multi-Index: conflicting mpl::begin and boost::begin > Sandeep Gupta <gupta.sandeep <at> gmail.com> writes: > > > Thanks for looking into this Vicente. I am not directly adding > > boost::mpl to the namespace. Please find attached the code. Below is > > the full error. > > > [...] > > /home/sandeep/Computing/boost_1_38_0/boost/range_ex/./detail/ > > adl_begin_end.hpp:27: > > error: in call to ‘begin’ [...] Adding to my previous post, I found the following in the Boost users list: http://lists.boost.org/boost-users/2006/01/16513.php Seems related, doesn't it? Alas the thread concludes with no satisfactory answer. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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Range_Ex and Multi-Index: conflicting mpl::begin and boost::begin
by Sandeep Gupta 18 Mar '09

18 Mar '09

Hi, I am under-impression that for_each construct of range_ex for all container concepts. However when I tried with multi-index it gave conflicting errors. Attached below is the code and corresponding errors. code: typedef multi_index_container< std::pair<value_type,int>, indexed_by< ordered_unique<member<pair<value_type,int>, value_type, &pair<value_type, int>::first> >, ordered_unique<member<pair<value_type,int>, int, &pair<value_type, int>::second> > > > mic; mic serialStore; for_each(serialStore, std::cout<<boost::lambda::_1<<' '); error: /home/sandeep/Computing/boost_1_38_0/boost/mpl/begin_end_fwd.hpp:22: error: ‘template<class Sequence> struct boost::mpl::begin’ is not a function, /home/sandeep/Computing/boost_1_38_0/boost/range/begin.hpp:96: error: conflict with ‘template<class T> typename boost::range_iterator::type boost::begin(T&)’ /home/sandeep/Computing/boost_1_38_0/boost/range_ex/./detail/adl_begin_end.hpp:27: error: in call to ‘begin’ /home/sandeep/Computing/boost_1_38_0/boost/mpl/begin_end_fwd.hpp:23: error: ‘template<class Sequence> struct boost::mpl::end’ is not a function, /home/sandeep/Computing/boost_1_38_0/boost/range/end.hpp:92: error: conflict with ‘template<class T> typename boost::range_iterator::type boost::end(T&)’ /home/sandeep/Computing/boost_1_38_0/boost/range_ex/./detail/adl_begin_end.hpp:35: error: in call to ‘end’ I apologies in advance if this is due to trivial omission. Thanks -sandeep

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[soc2009] Boost is in summer of code 2009: attention mentors
by troy d. straszheim 18 Mar '09

18 Mar '09

All, We've just been accepted as an organization in Google's Summer of Code 2009. Per this user's guide: http://socghop.appspot.com/document/show/program/google/gsoc2009/userguide those who have volunteered to mentor need to create a site-wide profile, and apply to mentor for Boost, then I'll click you in. Student applications start March 23rd. Until then: - Plan your application. - Brainstorm about project ideas on the mailing lists and IRC. - Familiarize yourself with existing work in the areas you are interested in by reading the mailing list archives and playing with existing Boost libraries. - Make proposals and get feedback. More as I get it. Thanks to Google and their Melange dev team. Looking forward to a good GSOC 2009. -t

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Boost::Format add-on
by Joel Falcou 18 Mar '09

18 Mar '09

Who is in charge of Format maintenance ? I would like to propose a simple patch to add an accessor to the number of arguments expected by the formating : int args() const { return num_args_; } Regards

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[array] change proposal for the c_array() function
by herve martin 18 Mar '09

18 Mar '09

Hi, I'm new in this mailing list .My interest are embedded software and code reuse. I would submit a simple change request in the boost::array library. The boost::c_array() function is expected to cast a boost::array<T,N> into a C-array but actually the returned type is a T* which is not exactly a reference on a C-array. to keep track of the static size and make sizeof( myarray.c_array() ) returning the real size of the C-array, I suggest to change: T* c_array() { return elems; } into T (&c_array())[N] { return *(T(*)[N]) elems; } by the way, I have developed a function helper array_cast<> whose purpose is to: * make a bit more friendly the syntax when casting to a C-array * check consistency between size of the input type and size of the target C-array for example, { long titi; char (&test)[4] = utils::array_cast<char>( titi ); test[0] = 0; } assuming that long is 32 bit long and char is 8 bit long, 'test[0]' is now a reference on the 1st byte of 'titi'. Moreover declaring test as a char(&)[5] would have failed in compiling since size of both types are not suitable (but the function provides some other way to force cast when sizes are not compatible) do you think that there could be any interest to include this function in boost library ? thanks, herve

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Why my subexpression doesn't work in Regex
by Qihong Wang 18 Mar '09

18 Mar '09

Hello, I'm a new boost and regex user. I tried a c++ regex sample as follows regex pattern("banan\$an\$*a"); string str = "bananana"; if(regex_match(str, pattern)) cout<<"---- pattern matched ----"<<endl; else cout<<"---- pattern unmatched ----"<<endl; To my surprise, the it printed out pattern unmatched. If I change str to "banan(an)a", the result is pattern matched. Feels like boost.Regex doesn't treat ( ) as subexpression. Any idea? Thanks, Qihong Wang

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[lexical_cast] Strange behaviour
by Robert Jones 18 Mar '09

18 Mar '09

Trying again 'cos I mucked up the code last time! This code #include <iostream> #include <boost/lexical_cast.hpp> int main() { using namespace std; try { unsigned int u=boost::lexical_cast<unsigned int>("-1"); cout << u << '\n'; } catch(const std::exception&) { cout << "Exception" << '\n'; } } produces 4294967295 on MSVC7 & 8 rather than an exception. Is it supposed to do this? Rob.

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[utility] new auto_buffer class --- RFC
by Thorsten Ottosen 18 Mar '09

18 Mar '09

Dear all, For a long time I have been missing this utility in my own work, and in boost related stuff too. I think there are a number of libraries in boost that can benefit from this utility. Libs like boost.format can be quite a bit more effective. So can logging libraries. etc. Basically boost::auto_buffer<T,N> is a C++ version of variable lenght array (from C99). It's based on Matthew Wilson's stlsoft::auto_buffer, which can be found described in his book "Imperfect C++". I have changed a few things though: // - no swap() and resize() provided // - works with allocators from Boost.Interprocess // - do not store T[N] on the stack, as this is bad when the // type has a non-trivial default constructor. // - handless non-pod types in an exception-safe manner // - has a fixed capacity, but a non-fixed size // - provides a non-growing (thus inlineable) push_back() Comments are most welcome. best regards -Thorsten

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reference to ‘_1’ is ambiguous
by Sandeep Gupta 18 Mar '09

18 Mar '09

Hi, This problem has appeared before on the list but in a different context. The following code std::vector<int> myvec; for_each(myvec, std::cout<<_1<<' '); gives the error: Serializer.h:78: error: reference to ‘_1’ is ambiguous /home/sandeep/Computing/boost_1_38_0/boost/lambda/core.hpp:69: error: candidates are: const boost::lambda::placeholder1_type& boost::lambda::<unnamed>::_1 /home/sandeep/Computing/boost_1_38_0/boost/bind/placeholders.hpp:54: error: boost::arg<1> <unnamed>::_1 Serializer.h:78: error: reference to ‘_1’ is ambiguous I believe boost/bind is getting included indirectly via some other library. I have tried several modification but none seem to work as I was quite reluctant to post a third mail on the list. Thanks, sandep

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pointer to member function of multi_index
by Sandeep Gupta 18 Mar '09

18 Mar '09

Hi, I am sure this is due to some trivial mistake; the statement to create a pointer member function insert of multi_index container fails in the following code: typedef multi_index_container< std::pair<int,int>, indexed_by< ordered_unique<member<pair<int,int>, int, &pair<int, int>::first> > > > mic; std::pair<mic_index::iterator, bool> (mic_index::*fn)(pair<int,int>) = &mic_index::insert; //compile error The error is due to mismatch in signature as given in the error: std::pair<boost::multi_index::detail::bidir_node_iterator<boost::multi_index::detail::ordered_index_node<boost::multi_index::detail::index_node_base<std::pair<int, int>, ... std::pair<boost::multi_index::detail::bidir_node_iterator<boost::multi_index::detail::ordered_index_node<typename SuperMeta::type::node_type> >, bool>... If need be I can post full error message. Appreciate any suggestions. Thanks sandeep

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correct usage of bind (pls ignore last email)
by Sandeep Gupta 17 Mar '09

17 Mar '09

Hi, The code below tries to chain function ft1 (argument is a pair) with function buildPair (returns a pair). template<typename X, typename Y> std::pair<X, Y> buildPair(X x, Y y) { std::pair<X,Y> apair(x,y); return apair; } int main() { typedef boost::function<void (std::pair<int,int>)> FuncType1_t; std::vector<std::pair<int,int> > myvec; FuncType1_t ft1 = bind(&std::vector<std::pair<int,int> > ::push_back, &myvec, _1); typedef boost::function<void(std::pair<int,int>)> FuncType2_t; FuncType2_t ft2 = bind(ft1, bind(buildPair<int,int>,_1,_2)); //compile fails return 0; } This fails. The problem however vanished if I replace the declaration "FuncType3 ft2..." with bind(ft1, bind(buildPair<int,int>,_1,_2))(3,5); So my question is what is correct type of bind(ft1, bind(buildPair<int,int>,_1,_2)); Thanks sandeep

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correct usage of bind
by Sandeep Gupta 17 Mar '09

17 Mar '09

Hi, Both the statements below bind function buildPair. While the first works the other fails. What could be a possible fix. Thanks in advance. //---- Function to be used by bind ------------------------- template<typename X, typename Y> std::pair<X, Y> buildPair(X x, Y y) { std::pair<X,Y> apair(x,y); return apair; } (std::cout<<buildPair(_1,_2).first<<' ')(1,2); ///--compiles fine--------- (bind(buildPair,_1,_2))(3,5); ///-fails------------ Thanks sandeep

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